Berry Fruit - Value-Added Products

BerryFruit

Value-Added Productsfor Health Promotion

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FOOD SCIENCE AND TECHNOLOGY

Editorial Advisory Board

Gustavo V. Barbosa-Cánovas Washington State University–PullmanP. Michael Davidson University of Tennessee–KnoxvilleMark Dreher McNeil Nutritionals, New Brunswick, NJRichard W. Hartel University of Wisconsin–Madison

Lekh R. Juneja Taiyo Kagaku Company, JapanMarcus Karel Massachusetts Institute of Technology

Ronald G. Labbe University of Massachusetts–AmherstDaryl B. Lund University of Wisconsin–Madison

David B. Min The Ohio State UniversityLeo M. L. Nollet Hogeschool Gent, BelgiumSeppo Salminen University of Turku, Finland

John H. Thorngate III Allied Domecq Technical Services, Napa, CAPieter Walstra Wageningen University, The Netherlands

John R. Whitaker University of California–DavisRickey Y. Yada University of Guelph, Canada

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BerryFruit

edited by

Yanyun Zhao

Value-Added Productsfor Health Promotion

CRC Press is an imprint of theTaylor & Francis Group, an informa business

Boca Raton London New York

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CRC PressTaylor & Francis Group6000 Broken Sound Parkway NW, Suite 300Boca Raton, FL 33487-2742

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Library of Congress Cataloging-in-Publication Data

Berry fruit : value-added products for health promotion / editor, Yanyun Zhao.p. ; cm. -- (Food science and technology ; 168)

Includes bibliographical references and index.ISBN-13: 978-0-8493-5802-9 (hardcover : alk. paper)ISBN-10: 0-8493-5802-7 (hardcover : alk. paper)1. Berries. I. Zhao, Yanyun, Dr. II. Title. III. Series: Food science and

technology (Taylor & Francis); 168. [DNLM: 1. Fruit. 2. Food Analysis. 3. Food Handling. 4. Nutritive Value. W1

FO509P v.168 2007 / WB 430 B534 2007]

QP144.F78B47 2007634’.7--dc22 2007001325

Visit the Taylor & Francis Web site athttp://www.taylorandfrancis.com

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Table of Contents

Part I Bioactive compounds of berry fruit ....................................................1

Chapter 1 Berry crops: Worldwide area and production systems............3

Bernadine C. Strik

Chapter 2 Chemical components of berry fruits........................................51

Stephen T. Talcott

Chapter 3 Berry fruit phytochemicals ..........................................................73

Luke R. Howard and Tiffany J. Hager

Chapter 4 Natural pigments of berries: Functionality and application ...........................................................................................105

M. Monica Giusti and Pu Jing

Chapter 5 Antioxidant capacity and phenolic content of berry fruits as affected by genotype, preharvest conditions, maturity, and postharvest handling .................................147

Shiow Y. Wang

Chapter 6 The potential health benefits of phytochemicals in berries for protecting against cancer and coronary heart disease................................................................................................187

Rui Hai Liu

Part II Quality and safety of berry fruit during postharvest handling and storage.................................................................................205

Chapter 7 Quality of berries associated with preharvest and postharvest conditions ......................................................................207

Elizabeth Mitcham

Chapter 8 Microbial safety concerns of berry fruit.................................229

Mark A. Daeschel and Pathima Udompijitkul

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Chapter 9 Postharvest handling, storage, and treatment of fresh market berries ............................................................................ 261

Cynthia Bower

Part III Processing technologies for developing value-added berry fruit products ...................................................................................289

Chapter 10 Freezing process of berries ..................................................... 291

Yanyun Zhao

Chapter 11 Dehydration of berries ............................................................ 313

Fernando E. Figuerola

Chapter 12 Commercial canning of berries...............................................335

Hosahalli S. Ramaswamy and Yang Meng

Chapter 13 Berry jams and jellies .............................................................. 367


Chapter 14 Utilization of berry processing by-products....................... 387

Yanyun Zhao

Index ..................................................................................................................... 411

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Preface

Berries are highly valued fruit crops for their unique flavors, textures, andcolors. In recent years, berries have been shown to provide significant healthbenefits because of their high antioxidant content, vitamins and minerals,fiber, folic acid, etc. In addition to fresh consumption, berry fruits are widelyused in beverages, ice cream, yogurt, milkshakes, jams, jellies, smoothies,and many other food products.

This book covers the basic functional chemicals (bioactive compounds),significant health benefits, shelf life, and microbial safety concerns associatedwith postharvest handling and storage, technologies to develop value-addedberry products with high quality, and significant nutraceutical benefits. Thisbook is divided into three parts: bioactive compounds of berry fruit andtheir health benefits, quality and safety of berry fruit during postharvesthandling and storage, and processing technologies for developing value-added berry fruit products.

Each chapter in this book is written by an international expert (orexperts), presenting information on the scientific background, researchresults, and critical reviews of the relevant issue, including a comprehensivelist of recently published literature, and case studies, thus providing valuablesources of information for further research and development of berry fruitfor the food industry.

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Editor

Dr. Yanyun Zhao

received her Ph.D. in food engineering from LouisianaState University, Baton Rouge, Louisiana, in 1993 and is now an associateprofessor in the Department of Food Science and Technology at Oregon StateUniversity, Corvallis, Oregon, with formal responsibilities in extension,research, and teaching. Dr. Zhao’s research efforts are in the area of value-added food products development, with an emphasis on using novel foodprocessing and packaging techniques for developing fruit- and vegetable-based functional foods. Dr. Zhao’s extension activities include providingleadership in identifying educational needs and creating, delivering, and eval-uating educational programs and materials in value-added fruit and vegetableproducts. Dr. Zhao teaches “Fruit and Vegetable Processing” and “FunctionalFoods” courses.

Dr. Zhao has published more than 40 journal articles and 8 book chapters,holds 6 patents, and has received more than 10 U.S. Department of Agricul-ture (USDA) competitive grants totaling about $1.5 million. Dr. Zhao serveson the editorial board of the

Journal of Food Processing and Preservation

, onadvisory boards of several industrial organizations, is an expert reviewer forseveral peer-reviewed journals and USDA competitive research grant pro-grams, and is an active member of the Institute of Food Technologists (IFT).

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Contributors

Dr. Bernadine C. Strik

Department of Horticulture Oregon State University Corvallis, Oregon

Dr. Stephen T. Talcott

Department of Nutrition and Food Science

Texas A&M University College Station, Texas

Dr. Luke R. Howard

Department of Food ScienceUniversity of ArkansasFayetteville, Arkansas

Dr. Tiffany J. Hager

Department of Food ScienceUniversity of ArkansasFayetteville, Arkansas

Dr. M. Monica Giusti

Food Science and Technology The Ohio State University Columbus, Ohio

Dr. Pu Jing

Food Science and Technology The Ohio State University Columbus, Ohio

Dr. Shiow Y. Wang

Fruit Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture

Beltsville, Maryland

Dr. Rui Hai Liu

Department of Food Science Cornell University Ithaca, New York

Dr. Elizabeth Mitcham

Department of PomologyUniversity of California Davis, California

Dr. Mark A. Daeschel

Department of Food Science and Technology

Oregon State University Corvallis, Oregon

Pathima Udompijitkul

Department of Food Science and Technology

Oregon State UniversityCorvallis, Oregon

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Dr. Cynthia Bower

U.S. Department of Agriculture Agricultural Research Service

Subarctic Agricultural Research Unit, University of Alaska–Fairbanks

Fairbanks, Alaska

Dr. Fernando E. Figuerola

Tecnología de AlimentosInstituto de Ciencia y Tecnología

de los Alimentos (ICYTAL) Universidad Austral de ChileValdivia, Chile

Dr. Hosahalli Ramaswamy

Department of Food Science and Agricultural Chemistry

McGill University, Ste. Anne de Bellevue

Quebec, Canada

Dr. Yang Meng

Department of Food Science and Agricultural Chemistry

McGill University, Ste. Anne de Bellevue

Quebec, Canada

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Part I

Bioactive compounds of berry fruits

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3

chapter 1

Berry crops: Worldwide area and production systems

Bernadine C. Strik

Contents

1.1 Introduction ...................................................................................................41.2 Worldwide berry crop production............................................................. 5

1.2.1 Strawberry ......................................................................................... 51.2.2 Raspberry........................................................................................... 8

1.2.2.1 Red raspberry..................................................................... 81.2.2.2 Black raspberry .................................................................. 9

1.2.3 Blackberry.......................................................................................... 91.2.4 Blueberry ......................................................................................... 11

1.2.4.1 Lowbush blueberry ......................................................... 111.2.4.2 Highbush blueberry ........................................................ 12

1.2.5 Cranberry......................................................................................... 131.2.6 Gooseberry and currant ................................................................ 131.2.7 Miscellaneous minor berry crops ................................................ 14

1.2.7.1 Lingonberry ...................................................................... 141.2.7.2 Hardy kiwifruit ................................................................ 141.2.7.3 Other berry crops ............................................................ 15

1.3 Growth and development .........................................................................161.3.1 Strawberry ....................................................................................... 161.3.2 Raspberry and blackberry ............................................................ 17

1.3.2.1 Raspberry .......................................................................... 171.3.2.2 Blackberry ......................................................................... 181.3.2.3 Raspberry-blackberry hybrids....................................... 19

1.3.3 Blueberry ......................................................................................... 201.3.4 Cranberry......................................................................................... 211.3.5 Gooseberry and currant ................................................................ 22

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4 Berry fruit: Value-added products for health promotion

1.3.6 Miscellaneous minor berry crops ................................................ 231.3.6.1 Lingonberry ......................................................................231.3.6.2 Hardy kiwifruit ................................................................ 24

1.4 Berry crop production systems ................................................................ 241.4.1 Strawberry ....................................................................................... 25

1.4.1.1 Annual production systems........................................... 251.4.1.2 Protected culture systems .............................................. 261.4.1.3 Perennial production systems ....................................... 27

1.4.2 Raspberry......................................................................................... 281.4.2.1 Summer-bearing red raspberry ..................................... 281.4.2.2 Primocane fruiting raspberry ........................................ 311.4.2.3 Off-season production systems ..................................... 311.4.2.4 Black raspberry ................................................................ 32

1.4.3 Blackberry........................................................................................ 321.4.3.1 Semierect blackberry .......................................................331.4.3.2 Erect blackberry ............................................................... 341.4.3.3 Trailing blackberry .......................................................... 35

1.4.4 Blueberry ......................................................................................... 361.4.4.1 Highbush and rabbiteye blueberry .............................. 361.4.4.2 Lowbush blueberry ......................................................... 38

1.4.5 Cranberry ........................................................................................391.4.6 Gooseberry and currant ................................................................ 421.4.7 Miscellaneous minor berry crops ................................................ 43

1.4.7.1 Lingonberry ...................................................................... 431.4.7.2 Elderberry .........................................................................431.4.7.3 Hardy kiwifruit ................................................................ 44

References.............................................................................................................. 45

1.1 Introduction

In 2005, there were more than 1.8 million acres of berry crops worldwide pro-ducing 6.3 million tons of fruit. The major berry crops grown, excluding grapes,are strawberries, black currants, blueberries, red raspberries, gooseberries, cran-berries, and blackberries. Other minor berry crops are also grown commercially,including black raspberries, hardy kiwifruit, chokeberries, elderberries, saska-toons, and lingonberries. In addition, harvesting of some berries from the wild,including blueberries, blackberries, raspberries, cranberries, and lingonberries,contributes significantly to the worldwide availability of berry fruit.

Berry crops are grown and sold via one of three marketing channels: (1)direct marketed through U-pick (customer harvested) or on-farm sales (growerharvested); (2) fresh sales via local stores or shipped to more distant markets;and (3) processed as frozen fruit, puree, dried, or juice—processed fruit maybe sold directly to consumers in small retail packages, but it is often purchasedby food manufacturers to make other products such as ice cream, yogurts,jams, jellies, juice blends, baked goods, cereals, and wines, for example.


Chapter 1: Berry crops: Worldwide area and production systems 5

Production systems vary depending on whether the main market is forprocessed or fresh fruit. However, farms that have a fresh market focus mayprocess a portion of their production that does not meet fresh fruit gradestandards, when fresh prices are too low, or when there is a demand forprocessed fruit. Thus many growers access more than one marketing channeland grow a range of berry crops (and other crops as well) to diversify andimprove their chances of success and minimize risk. Growers who are tar-geting large fresh or processed markets often work with a local wholesaler(fresh shipper or processing plant or “packer”) who sets prices and providesguidelines for harvesting and packaging. Some wholesalers provide theproprietary cultivars grown.

Most berry crops are grown with conventional or integrated pest man-agement practices. However, there is an increasing market demand fororganically grown berry crops and thus organic acreage is increasing.

This chapter details current berry crop acreage and production world-wide. The botanical classifications and growth and development of the majorand many of the minor berry crops are described to provide the necessaryfundamentals. The most common production systems are described by crop,with any differences among regions noted.

1.2 Worldwide berry crop production

1.2.1 Strawberry

There were more than 600,000 acres and 3.9 million tons of strawberriesproduced worldwide in 2005 (Table 1.1). More than half the acreage was inEurope, with Poland, Serbia and Montenegro, Germany, Ukraine, and Italy

Table 1.1

Production of Major Berry Crops Worldwide, in Descending

Order of Area Planted, 2005

Berry crop Region Area (acres)Production

(tons)

Strawberries Africa 16,264 207,130Asia 134,670 721,566Central America 1,142 10,869Europe 327,205 1,241,718Middle East 35,360 225,475North America 75,664 1,299,600Oceania 4,643 33,547South America 14,685 131,964World total 609,633 3,871,869

Red and black currants Asia 179,222 445,417Europe 219,069 486,675Oceania 3,855 7,826World total 402,146 939,918

(

Continued

)



being the leading producers. In fact, 40% of the acreage in Europe is in Poland,with most of their production being processed. There is strong year-rounddemand for high-quality fresh strawberries in Europe. Fresh strawberries areproduced in southern Spain and Italy from February to May and are exportedto countries in north and central Europe. Traditional cropping systems are

Table 1.1 (Continued)

Production of Major Berry Crops Worldwide, in

Descending Order of Area Planted, 2005

Berry crop Region Area (acres)Productions

(tons)

Blueberries—Highbush Africa 741 350Asia 1,754 1,445Europe 9,736 19,535North America 74,585 152,350Oceania 2,434 3,650South America 18,039 17,500World total 107,289 194,830

Blueberries—Lowbush North America 172,840 100,750World total 280,129 295,580

Red raspberries Africa 163 143Asia 100,428 131,468Europe 104,069 230,918North America 21,164 82,783Oceania 927 761South America 25,950 57,320World total 252,701 503,393

Gooseberries Asia 42,056 67,847Europe 54,520 83,050World total 96,576 150,897

Cranberries Asia 26,687 36,927Europe 247 551North America 46,245 377,056South America 1500 3000World total 74,679 417,534

Blackberries Africa 247 220Asia 3,830 29,051Central America 4,052 1,753Europe 19,007 47,386North America 17,690 65,170Oceania 734 4,023South America 3,939 6,975World total 49,499 154,578

Black raspberries Asia 50 250North America 1,300 235World total 1,350 485

Source:

United Nations Food and Agriculture Organization (FAO) (strawberry, cur-rants, gooseberries); Strik and Yarborough

1

(Brazelton, D., personal communication;blueberries); Strik et al.

2

(blackberries); FAO and academic colleagues (red raspberry).



used to produce fresh fruit in northern Europe and Scandinavia from Junethrough August. Protected culture using greenhouses and tunnels is used inmany European countries to provide “out-of-season” fresh fruit for 11 monthsof the year (from end of February until mid-January) in temperate climates.The next largest production region for strawberries is Asia (Table 1.1), where65% of the acreage is in the Russian Federation, 14% each in Korea and Japan,and 5% in Kazakhstan.

The United States had 51,595 acres of strawberries and 1.1 million tons,making it the largest producer in North America (Table 1.1). In the UnitedStates, 63% and 13% of the total acreage is in California and Florida, respec-tively, where strawberries are produced using annual production systemsand more than 75% is fresh marketed. Fresh strawberries are availableyear-round using traditional annual and perennial production systems.Other states in the United States produce strawberries predominantly usingperennial production systems, with the third largest producer, Oregon (6%of acreage), processing more than 95% of their production. It is difficult forstates like Oregon, that produce high-quality processed strawberries, to com-pete with processed fruit produced at lower cost in Mexico and California.For example, strawberry acreage in Oregon has declined from 7800 acres in1988 to 2200 acres in 2005. Most of this decline can be attributed to compe-tition from processed fruit produced elsewhere, particularly in California.Historically California strawberry production is about 75% fresh marketed;however, they still produce more than 250 million pounds of processed fruit.While this processed fruit is considered inferior to that from cultivars bredspecifically for processing produced in Oregon and other areas of the PacificNorthwest, it is a by-product and is sold at lower cost. In addition, yield inthe annual production system used in California is up to six times higherthan in the perennial systems used in the Northwest. These higher costs ofproduction have made it difficult for Oregon growers to compete. It is likelythat certain manufacturers will always demand premium quality fruit forcertain products, so the future for a small, niche market industry in Oregon,for example, seems good.

Mexico produced 165,632 tons of strawberries on 13,378 acres usingannual production systems. Mexico typically exports about 30,000 tons/year,of which 70% is processed and 30% is fresh. Most of the exports are to theUnited States, but fruit is also shipped to Canada, Japan, and Europe. In2005, Canada had more than 10,600 acres producing strawberries in peren-nial production systems for local fresh markets and processing.

More than 72% of the strawberries in the Middle East (Table 1.1) are grownin Turkey. Other strawberry-producing countries in this region are Iran (21%),Israel (3%), Lebanon, Palestine, Cyprus, and Jordan. Strawberry productionin Turkey has increased considerably over the last 10 years. Strawberries areproduced in most areas of Turkey, mostly on small family farms.

Egypt and Morocco accounted for 84% of the total acreage in Africa(Table 1.1). There is also some strawberry production in South Africa, Tunisia,and Zimbabwe. Production in most areas uses Californian cultivars in annual



production systems. Fresh fruit from Egypt is exported mainly to the UnitedKingdom.

In South America (Table 1.1), strawberries are planted in Chile (27% ofacreage), Peru (24%), Columbia (13%), Venezuela and Brazil (7%), Paraguay(5%), and Ecuador (3%). Annual production systems using Californian cul-tivars are common. Nearly 60% of strawberries in South America are pro-duced between June and November, with the remainder produced betweenNovember and May. About 50% to 70% of the strawberries are shipped fresh,while 30% to 50% are shipped frozen.

There is also some strawberry production in Central America, mainly inGuatemala and Costa Rica, and in Oceania, with 79% of the acreage inAustralia (Table 1.1).

Currently it is not easy to obtain acreage information on organic straw-berry production. However, there is some organic production in mostregions. In California, where accurate statistics are reported, there were 965acres of organic strawberries in 2006 (3% of the total acreage).

Fresh strawberries are most commonly shipped in clamshell containers.Strawberries are processed as individually quick frozen (IQF), bulk frozen,sliced and sugared (“4

+

1”; 4 pounds fruit

+

1 pound sugar), freeze-dried,pureed, or juice/concentrate.

1.2.2 Raspberry

1.2.2.1 Red raspberry

In terms of area planted, red raspberries are the fourth most important berrycrop in the world (Table 1.1). Europe accounts for the largest portion of redraspberry acreage. Serbia and Montenegro (40% of the acreage) and Poland(34%) are the largest red raspberry producers in Europe, together producingmore than 161,500 tons in 2005, mainly for processing. Other countries pro-ducing red raspberries in Europe are the United Kingdom (4%), France (3%),Hungary (3%), Spain (3%), Bulgaria (3%), Germany (3%), and Belgium,Croatia, Czech Republic, Estonia, Finland, Norway, Portugal, Romania, Swit-zerland, Sweden, Slovakia, The Netherlands, Italy, Ireland, and Denmark.More than 60% of the total production in most western European countriesis fresh marketed.

Asia accounts for about 40% of world acreage (Table 1.1); however, most(81%) of Asia’s production is in the Russian Federation. More than 12,350acres were reported in the Ukraine, but an additional 30,000 acres of wildraspberries are harvested. The next largest raspberry producer in Asia isKorea, with 3212 acres; much of their production is locally used to producewine. Other countries in Asia with red raspberry acreage are the Republicof Azerbaijan, the Republic of Moldova, and China.

Chile is the only country in South America with significant red raspberryacreage (Table 1.1). Only 7% of Chilean production is for domestic use, therest is exported, mainly (85%) as processed product. Frozen red raspberriesfrom Chile are exported to Europe, the United States, Canada, and Australia.



North America produces 16% of the red raspberry tonnage in the world(Table 1.1). The United States has about 14,826 acres, mostly in WashingtonState, but significant production also occurs in Oregon and California. Canadahas 5560 acres, mostly in British Columbia, and most of this fruit is processed.The 778 acres in Mexico are mainly grown for the fresh export market. InOceania, most of the acreage is in New Zealand (80%). Zimbabwe andMorocco produce red raspberries in Africa (Table 1.1).

Red raspberries for the fresh market are most commonly sold in clam-shell containers. Raspberries are processed as IQF, bulk frozen, freeze-dried,puree, or juice/concentrate.

1.2.2.2 Black raspberry

The only countries reporting significant acreages of black raspberries areChina and the United States, for a total world production of 485 tons from1350 acres (Table 1.1). Korea has substantial new, but unreported, acreagebeing used for the production of berries for liqueur. In the United States,99% of the black raspberry acreage is in Oregon, with almost all of theproduction processed as bulk frozen, puree (seedless), freeze-dried, or juice/concentrate.

1.2.3 Blackberry

Blackberry acreage worldwide has increased an estimated 45% in the last10 years. In 2005, there were about 49,498 acres of blackberries planted andcommercially cultivated worldwide (Table 1.1). Blackberries are now moreavailable to consumers. In 1990, most of the blackberry production in theeastern United States was U-pick or direct marketed and less than 2% wasprocessed.

3

In contrast, in 1990 more than 90% and 50% of the trailingblackberry crop in Oregon and California, respectively, was processed. Black-berries were not found on grocery store shelves in the eastern United States,and only rarely in the western United States in 1990.

4

However, in the late1990s, Chester Thornless became a major shipping blackberry, as it wasfound to have good fruit firmness. Navaho, from the University of Arkansas,was found to have excellent shelf life and could be shipped. These and othercultivars contributed to a major shift in the production outlook for blackber-ries from that of a locally marketed crop to one shipped for retail marketing.

4

Also, the shipping of blackberries from Chile, Guatemala, and Mexico to theUnited States provided fresh blackberries during the “off-season” autumn,winter, and spring months and increased consumer awareness of this berrycrop and consequently increased sales of U.S.-produced “in-season” fruit.

Wild blackberries, not included in Table 1.1, still make significant con-tributions to worldwide production, and although accurate data are hard toobtain, there were an estimated 19,770 acres of wild blackberries harvestedin 2005 with a total reported production of 14,837 tons.

2

In some regions, thefruit harvested from wild blackberries may negatively impact sales of com-mercially grown fruit.



Worldwide blackberry production was 154,578 tons in 2005, not includ-ing the wild production mentioned above (Table 1.1). The largest blackberryproduction region is Europe, with Serbia accounting for 69% of the black-berry acreage in Europe. Ninety percent of Serbia’s production is processedand exported. Hungary was the next largest producer in Europe, with3950 acres (21% of the total area) and 13,227 tons. Countries in Europewith 250 acres or more are the United Kingdom, Romania, Poland, Germany,and Croatia. The area in Poland has doubled in the last 10 years. There were550 tons produced in 2005, with 80% processed, and most of this wasexported, as was most of their fresh production.

The United States accounted for 67% of the blackberry acreage in NorthAmerica, the second largest in the world, after Serbia. The area planted inthe United States increased 28% from 1995 to 2005. The United States hadthe highest production—35,099 tons—in the world in 2005. Sixty-five percentof the blackberries cultivated in the United States are planted in Oregon—7755 acres. More than 95% of the total production of 25,185 tons was pro-cessed, with the remaining marketed fresh, and all for domestic use.

The next largest blackberry-producing state in the United States isCalifornia, with 700 acres and 2600 tons in 2005. Most of the blackberryproduction in California is now located on the north-central coast and hasa fresh market focus from mid-May through August. Other blackberry-producing states are Texas, Arkansas, and Georgia.

5

Mexico accounts for 32% of the planted area in North America, with 5683acres. Blackberry production in Mexico has increased from 568 acres in 1995 andis projected to grow to at least 12,355 acres by 2015. Most of the Mexican produc-tion targets fresh export markets to the United States. In 2004, Mexico exported8245 tons to the United States, more than double their export volume in 2002.

In Central America (Table 1.1), Costa Rica (3830 acres) and Guatemala(222 acres) reported commercial production. Of the 1653 tons produced inCosta Rica, less than 15% was exported. Currently most is used for localprocessing and fresh consumption. Guatemala is the main country in CentralAmerica that ships fresh blackberries to the United States.

Ecuador accounts for 53% of the planted area in South America (Table 1.1),with 2100 acres. There was an estimated 30% growth in planted area from1995 to 2005, but little growth is projected for the next 10 years. Only 15%of their estimated 1421 tons of production is exported for the fresh market,mainly due to the soft fruit of the species they grow (

Rubus glaucus

Benth.)and the Mediterranean fruit fly (

Ceratitis capitata

Wiedemann). Chile has 1111acres of commercial blackberries with a total production of 4275 tons, notincluding the 6393 tons harvested from wild plantings and exported as aprocessed product. The area planted increased 50% from 1995 to 2005 andis projected to be 1975 acres in 2015, provided competition from Mexico inthe fresh market does not adversely affect the cost of production and com-petitiveness in the processed portion of their industry. In 2004, Chileexported 10,670 tons of processed fruit (55% to 65% was harvested fromintroduced wild species) and 210 tons of fresh fruit. Their fruiting season is



from November to March. Brazil had 617 acres and produced 860 tons in2005, with only 15% exported.

China accounted for all of the production in Asia (Table 1.1). Most ofChina’s production is in the Jiangsu Province, but the newest regions, theLiaoning, Shandong, and Hebai Provinces, are projected to grow the mostin the next 10 years, when China is expected to have 5436 acres. Most of theproduction in China is processed, with 70% of processed fruit and 10% oftheir fresh production exported.

Most of the blackberry area in Oceania (Table 1.1) is planted in NewZealand, which had 640 acres and 3690 tons in 2005. The area in Oceania isprojected to grow by about 35% in 10 years. The fruiting season in New Zealandis from November through April, with almost all of their blackberry productionconsisting of trailing types, mainly Boysen. Almost all of their production isprocessed, with 55% of that exported.

South Africa is currently the only African country with blackberry pro-duction (Table 1.1). However, no fresh fruit is exported because of the dis-tance to the major markets of Europe.

Projections for the greatest growth in the next 10 years are in Romania(900%), Poland (200%), Mexico (117%), Chile (76%), Hungary (50%), China(42%), and the United States (20%). There may be 66,797 acres of commercialblackberries worldwide, not including production from harvested wildplants, in 2015.

2

Blackberries for the fresh market are most commonly sold in clamshellcontainers. Blackberries are processed as IQF, bulk frozen, puree (with orwithout seeds, depending on the cultivar), freeze-dried, or juice/concentrate.

1.2.4 Blueberry

Blueberries have become a major crop worldwide. Strong markets for pro-cessed and fresh fruit have resulted in good returns for growers and anincrease in planted area. The growth in markets and production is relatedto the positive health benefits of blueberries. These benefits have been usedin marketing campaigns since 1997. Over the last 10 years, demand forblueberries has exceeded supply. New cultivars, better adapted to “nontra-ditional” growing areas, have expanded production worldwide. From 1995to 2005, worldwide highbush blueberry acreage increased by 90%.

In many areas of the world, wild species of blueberries are harvested forpersonal and commercial use. Data on total production are often difficult orimpossible to obtain. For example,

Vaccinium uliginosum

L. is harvested in China,

Vaccinium myrtillus

L. in Europe, and various species in the United States, oftenmarketed as “huckleberries.” I will not include information on the productionof any native

Vaccinium

species here, other than the lowbush blueberry.

1.2.4.1 Lowbush blueberry

Lowbush blueberry fields consist mainly of native clones of

Vaccinium angusti-folium

Ait. with some clones of

Vaccinium myrtilloides

Mich. mixed in, depending



on the region. In Canada and the United States, native stands are managedand harvested for commercial production. Fruit are often marketed as “wildblueberries,” with more than 97% of the total production being processed. In2003, processed lowbush blueberry fruit accounted for 68% of the total pro-cessed fruit (all types of blueberries) produced in North America and they areexpected to continue to account for a significant share of this market.

In 2003, the total area of lowbush blueberries managed in North Americawas 172,845 acres, a 33% increase from 10 years earlier.

1

Since lowbushblueberries are native, this increase in area reflects a larger portion of nativestands being managed for harvest because of the strong blueberry market.There were 65,442 acres of lowbush blueberries in the United States, mainlyin Maine, and 107,404 acres in Canada, mainly in Quebec, Nova Scotia, andNew Brunswick. Only half of the total area of lowbush blueberries is har-vested annually because of alternate-year pruning practices.

5

Total lowbushblueberry production in North America in 2003 was 111,058 tons, withapproximately 99% sold for processing.

The managed area of lowbush blueberries in North America is expectedto increase by 10% by 2013.

1

The major limitation for expansion of thisindustry is finding native stands that can be economically brought intoproduction.

1.2.4.2 Highbush blueberry

In 2005, there were an estimated 107,289 acres of highbush blueberries(

Vaccinium corymbosum

L.) planted worldwide with a total production of196,900 tons, a 20% and 51% increase in acreage and production, respectively,from what was reported in 2003.

6

North America accounted for about 70%of the planted area and 77% of the total highbush blueberry production inthe world (Table 1.1). Acreage in North America increased an average of2535 acres/year from 2003 through 2005. Most of the North American acre-age was in the United States—60,975 acres—but there were 13,500 acres inCanada, mainly in British Columbia, and about 180 acres in Mexico in 2005.

South America accounted for about 17% of the world area in 2005 (Table 1.1).Fruit is harvested by hand from the end of September through April, depend-ing on the country and region. Most of the fruit is exported to markets inthe Northern Hemisphere. Blueberry production in South America startedin Chile, which still accounts for 62% of the area planted and 80% of thetotal production. The remaining blueberry production is in Argentina.

In Europe, 95% of the total production (Table 1.1) is marketed in Europe.There were an estimated 3954 acres in Poland, 3954 acres in Germany, 741 acresin France, 852 acres in The Netherlands, 593 acres in Spain and Portugal,445 acres in Italy, and 49 acres in the United Kingdom.

Oceania accounted for about 2% of the world’s blueberry area in 2005(Table 1.1), with about half the area in each of New Zealand and Australia.South Africa had 741 acres and produced 350 tons of blueberries in 2005 (Table 1.1).

There is tremendous interest in blueberries in Asia. Plantings areexpected to increase steadily in this region. Japan has about 1112 acres and



China 642 acres (Table 1.1). However, interest in planting blueberries is strongin both countries. For example, in China there may be more than 1500 acresplanted by 2008.

Total highbush blueberry production in the world in 2005 was 194,830 tons,with approximately 63% sold for the fresh market. Blueberries for the freshmarket are most commonly sold in clamshell containers. Blueberries areprocessed as IQF, bulk frozen, freeze-dried, pureed, or juice/concentrate.

Many areas producing highbush blueberries have some limitations toexpansion of the area planted, particularly in North America and Europe.These limitations include cold winter climate and insufficient cold hardinessof the present cultivars, lack of suitable soils, insufficient planting stock,pressures for urbanization, and the cost of establishment. Still, many projectsignificant growth in the planted area of highbush blueberries in the next 5to 10 years. The markets for fresh and processed fruit will need to continueto be strong to support the projected increase in supply.

1.2.5 Cranberry

There were a reported 74,679 acres of cranberries harvested worldwide in 2004(Table 1.1). The United States is the world’s largest producer, with 39,200 acresof the large-fruited cranberry (

Vaccinium macrocarpon

Ait.) and 74% of totalworld production. In the United States, Wisconsin and Massachusetts havethe largest cranberry acreage, accounting for 80% of the total. Other statesproducing cranberries are New Jersey, Oregon, and Washington.

Belarus has the second largest area, with 19,768 acres, but the yield of thesmall-fruited cranberry (

Vaccinium oxycoccos

L.) they produce is relatively low,with a total production of 25,353 tons. In comparison, Canada had the secondhighest production in the world, harvesting 68,556 tons of large-fruited cran-berry from 7045 acres. The area in Europe is currently reported as 247 acres,all in Romania; however, there are commercial cranberry plantings in Irelandand Poland that are not yet reported in official statistics. Other countriesproducing the small-fruited cranberry are Ukraine, Latvia, and the Republicof Azerbaijan in west Asia. In South America, the only country producing thelarge-fruited cranberry on established beds is Chile, with 1500 acres (Table 1.1).

The majority of cranberry production worldwide is processed. In theUnited States, 94% of total production was processed in 2004. Cranberriesare processed for juice and sauces, and are dried. Chile exported 40 tons offresh cranberries in 2004; however, fresh cranberries in the Northern Hemi-sphere are typically only sold during Thanksgiving (October in Canada andNovember in the United States) and Christmas. Fresh cranberries are storedfrom harvest (September or October) until the time of sale.

1.2.6 Gooseberry and currant

There were 96,576 acres of gooseberries (

Ribes uva-crispa

L.) and 402,146 acresof red and black currants (

Ribes rubrum

L. and

Ribes nigrum

L., respectively)worldwide in 2005 (Table 1.1). Currants are produced mainly in Europe and



Asia, with black currants being the most common type grown; black currantsare mainly processed into juice, but they are also used for jams, jellies,liqueurs, and colorings.

7

Almost all of the currant acreage in Asia is plantedin the Russian Federation. In Europe, countries with currants are Poland(47% of acreage), Germany (23%), Ukraine (5%), and the United Kingdom,Austria, the Czech Republic, France, Estonia, Denmark, and Finland, all with2% to 3% of European acreage. The predominant acreage of red currants isin Poland and Germany, with lesser acreages in Belgium, France, Holland,and Hungary.

7

Red currants are used mostly for juices and other processedfood items, often in combination with other fruits. White currants are usedin parts of Europe for baby food and in Finland for sparkling wines.

8

Ninetypercent of the acreage in Oceania is in New Zealand. Although some com-mercial acreage of gooseberries and currants exists in North and SouthAmerica, it is relatively small and scattered. For example, currants are pro-duced for the fresh market in Chile and for the fresh and processed marketsin the United States (Oregon).

Gooseberries are mainly grown in Asia and Europe (Table 1.1), with thelargest area, 42,000 acres, in the Russian Federation and 30,885 acres inGermany. The next largest producer is Poland, with 8400 acres. Althoughsome commercial acreage of gooseberries exists in North America, it is rel-atively small and scattered. Gooseberries are grown for the fresh market andprocessing, mainly canning, in Oregon. Worldwide, gooseberries are pro-cessed mainly for jams and are sold to a limited extent for the fresh market.

1.2.7 Miscellaneous minor berry crops

1.2.7.1 Lingonberry

The commercial acreage of lingonberries in established plantings is estimatedat 70 acres worldwide. Actual production statistics for this crop are difficultto obtain. Most of the lingonberry production worldwide is harvested fromwild stands.

1.2.7.2 Hardy kiwifruit

Kiwifruit is native to Southeast Asia. There are more than 50 species in thegenus

Actinidia

, and many have commercial potential. The most commonkiwifruit species grown commercially is

Actinidia deliciosa

cv. Hayward. Con-sumers are very familiar with this brown, fuzzy fruit. Hayward is growncommercially in New Zealand, Italy, Japan, France, Australia, Greece, Chile,and California. Hardy kiwifruit [

Actinidia arguta

(Siebold & Zucc.) Planch.ex Miq], however, are much more limited in their production and, unlikeHayward, are often marketed along with other berry crops.

Ananasnaya is the most widely grown cultivar of hardy kiwifruit in theworld and may also be known or marketed under alternate names including“baby kiwifruit,” “grape kiwi,” “wee-kee,” and “cocktail kiwi.” In 2003, about250 acres of Ananasnaya were grown commercially worldwide, in theUnited States, New Zealand, Canada, Chile, Italy, France, Germany, and



The Netherlands

9

more than one-third of this acreage was in Oregon. Freshfruit of Ananasnaya have been well received in the San Francisco and LosAngeles, California, markets and in Japan, fetching high prices. In addition,private industries are working on developing processed products.

The commercial acreage has been limited mainly by marketing factors,such as development of fresh markets for this relatively unique fruit, therange in fruit size, the limited ripening period, and the relatively shortstorage and shelf life compared to fuzzy kiwifruit. The continued developmentof processed markets likely will strengthen this industry.

1.2.7.3 Other berry crops

Every culture around the world has native crops that are important locallyand some of these have become important berry crops.

10

Other berry cropsgrown commercially include the elderberry (

Sambucus canadensis

L.), inNorth America and its counterpart

Sambucus nigra

L. in Europe. The purplish-black berries, about 1/4 in. in diameter, are produced on large cymes upto 1 ft in diameter. The stems of the American elder have long been usedfor musical flutes and pipes for conducting liquids. North American Indi-ans and early pioneers adapted the hollow stems for use as a tap to drawsap from sugar maple trees. Tannin in the bark and roots of elderberry wasused in tanning leather. The leaves, flowers, and fruit provided dyes forleather, baskets, and other articles made by North American Indians. Theberries and oil pressed from seeds have been used to flavor wine. All partsof the elderberry have been used in medicine, and the powdered,freeze-dried, encapsulated fruit of

S. nigra

is a major use for this crop. Atpresent, elderberry fruit is used for various culinary purposes: in sauces,alone or combined with other fruit in tarts and pies, fruit juice, jelly, andred wine.

11

Saskatoons, also called juneberries or serviceberries (

Amelanchier alnifolia

Nutt.), are grown commercially mainly in Alberta and Saskatchewan, Canada.Various species of

Amelanchier

are used as ornamentals for their showyflowers and edible, dark purple fruit that look like blueberries. However,this plant does not produce true “berries”; botanically, this species producesa pome fruit. The fruit was used by North American Indians in makingpemmican, a semidry mixture of fruit and meat. Early pioneers used this asa major source of fruit. The fruit can be eaten fresh, in pies or other bakeddesserts, canned, frozen, or made into wines, jellies, or syrup.

The chokeberry [

Aronia melanocarpa

(Michx.) Elliott] is grown commer-cially as a processed fruit product in eastern Europe and to a limited extentin North America. Plants produce dark purple berries, about 1/4 in. indiameter, that are used mainly for juice production.

Some wild blueberries, commonly called “huckleberries,” are not only har-vested from wild stands, but are planted and commercially cultivated. An exam-ple of this is the “evergreen huckleberry”

Vaccinium ovatum

Pursch.), grown toa very limited extent in established plantings in Oregon. The small, dark blueto purple fruit are processed and mainly used for “huckleberry” jam.



1.3 Growth and development

Vegetative and reproductive growth of berry crops is influenced by environ-ment, particularly photoperiod and temperature, soil type, and cultural prac-tices such as fertilization, irrigation, and production systems. This chapterhighlights the stages of growth and fruit development. Cold hardiness is notcovered here, but is well reviewed in other publications.

8,12–18

1.3.1 Strawberry

The cultivated strawberry (

Fragaria

×

ananassa

Duch., family Rosaceae) is aperennial plant adapted to a wide range of climates. There are many otherspecies of

Fragaria

found worldwide, however, the only other species growncommercially to any extent are

Fragaria vesca

L., the wood or alpine straw-berry, and

Fragaria chiloensis

(L.) Mill., the beach strawberry.The strawberry plant has trifoliate leaves arranged spirally around a

compressed stem, called a crown.

19

Buds in the axils of each leaf may developinto a branch crown, inflorescence, a runner, or remain dormant. Branchcrowns tend to develop under short day length (less than 10 hours), whereasrunners are promoted under long days (more than 10 hours). Runners consistof an aboveground stem with a new daughter plant produced at the secondnode. Daughter plants may also produce runners, thus leading to a runner“string.” The original plant established is often called the “mother plant.”Some types or cultivars of strawberry produce more runners than others.Runner production may also be manipulated through chilling received incold storage, as is done in the California production system. Roots arise fromthe base of the crown, with 90% of the root system found in the upper 6 in.of soil.

20

The two main types of strawberry grown worldwide are short-day types(called “June bearers” in the northern hemisphere) and day-neutral types.Short-day cultivars initiate flower buds when the day length or photoperiodis less than 14 hours, whereas day-neutral cultivars typically initiate budsevery 6 weeks throughout the growing season.

13

However, at low tempera-tures (about 50

°

F to 59

°

F) most cultivars initiate flowers regardless of thephotoperiod, while at high temperatures (about 77

°

F), flower bud initiationis almost inhibited.

13

The impact of light intensity and temperature on straw-berry plant growth is well reviewed by Darnell.

13

Strawberry inflorescences often produce a terminal flower (primary),two secondary, four tertiary, and eight quaternary flowers.

20

However, asbreeding programs have selected for larger fruit, they have selected for muchsimpler inflorescences that commonly contain only one to three flowers.Individual flowers typically have 10 sepals (calyx), 5 petals, 20 to 30 stamen,and 60 to 100 pistils, depending on the flower order.

21

The flowers are mainlypollinated by bees.

The strawberry is an aggregate or accessory fruit composed of a fleshy,red receptacle with achenes (fertilized ovules, often called “seeds”) arrangedspirally on the outside of the receptacle. Growth of the receptacle depends



on the successful fertilization of the ovules and the size and shape of themature fruit is a function of the number and arrangement of achenesformed.

22

Fruit development from pollination to ripe fruit ranges from 20 to50 days, depending on the cultivar and temperature. The primary fruit ripensfirst and produces the largest fruit (“berry”), then the secondary, and so on.

1.3.2 Raspberry and blackberry

The red raspberry (

Rubus idaeus

L.), the black raspberry (

Rubus occidentalis

L.),and the blackberries (

Rubus

sp.) belong to the family Rosaceae. This groupor genus (

Rubus

) is collectively called “brambles” in eastern North Americaand “caneberries” in western North America. Most blackberries and rasp-berries have spines, although spine density can vary considerably amongcultivars, with some being genetically thornless.

Raspberry and blackberry plants have perennial root systems andcrowns (base of the plant). However, the canes are biennial, living for only2 years. Cane growth (increases in length) occurs only in the first year, whencanes are called primocanes. In year two, canes are called floricanes. Thesecanes flower, fruit, and then die after fruiting. In any year, except the plantingyear, there are both cane types present.

1.3.2.1 Raspberry

The red raspberry (

R. idaeus

) is commonly divided into two types based onfruiting habit: “summer bearers” or floricane fruiting types (e.g., Tulameen,Meeker, Glen Ample), and “primocane fruiting” types (e.g., Heritage, AutumnBliss, Polka). The only black raspberry harvested commercially is

R. occidentalis

(e.g., Munger). Purple raspberries (e.g., Royalty), hybrids between red andblack raspberries, are grown to a very limited extent, mainly in eastern NorthAmerica. Yellow-fruited

R. idaeus

, in which the fruit color is due to a recessivemutation, is also grown in small quantities for specialty markets.

Wherever raspberry species are found, they have been harvested fromthe wild; however, several species have interest beyond their area of origin.

10

Raspberry species harvested in the wild include

Rubus chamaemorus

L., thecloudberry, and

Rubus arcticus

L., the arctic raspberry, both native to alpineand circumpolar regions and having a dwarf, herbaceous, annual bearinghabit. Hybrids of the European

R. arcticus

and the American

Rubus stellatus

are marketed in northern Europe.

23

Primocanes are produced from buds at the base of floricanes at the crownor from buds on roots in red raspberry. Black raspberries only produce newprimocanes from buds on the crown. Generally, in summer-bearing red andblack raspberries, primocanes are vegetative the first year and fruit thesecond year on the entire length of the floricane. Primocane fruiting rasp-berries produce a relatively large crop at the tip of the primocane and willproduce a floricane crop on the base of the second-year cane.

Raspberries have an extensive root system. Roots start growing in thespring after bud break. If water is adequate, most root growth occurs inmidsummer and growth continues in the fall after top growth has stopped.



In summer-bearing raspberries, flower bud initiation for next year’s cropoccurs as the day length shortens and temperatures start to cool in latesummer. Flower bud development starts at the tip of the cane and progressesbasipetally.

Flower bud initiation in primocane fruiting cultivars is not dependentupon photoperiod or cooler temperatures, but rather is based on the phys-iological age of the cane, starting at the tip.

24,25

Carew et al.

26

reviewed howthe growth cycles of summer-bearing and primocane fruiting raspberries arecontrolled by the environment, the cultivar, and cultural practices.

Once plants enter dormancy, a certain number of chilling hours (tem-peratures between 32

°

F and 45

°

F) are required before the plant can grownormally. Although the exact chilling requirements of many cultivars are notknown, many of the summer-bearing red raspberries grown in the northernhemisphere have a chilling requirement of 800 to about 1400 hours. Pri-mocanes overwinter as dormant canes and become floricanes when growthstarts the following spring.

Buds break along the floricane producing fruiting laterals, the lengthsof which are cultivar dependent. Cultivars that are suited to machine har-vesting generally have fruiting laterals that are not too short or too long andare not brittle. The range in flower opening time along the fruiting lateral,coupled with a slightly earlier emergence of laterals at the tip of the cane,leads to a range in fruit ripening time within a cultivar. Most summer-bearingcultivars have a ripening season of about 30 days, although some have aseason as long as 55 days.

Raspberry flowers have five sepals, five petals, many stamens, and manypistils arranged spirally around a receptacle. Commercial red and blackraspberries are self-fertile, in that a cross pollinator is not required. However,they do require insect/bee transfer of pollen to the pistils. Insufficient pol-lination or fruit set within a flower leads to the development of crumblyfruit. Some viruses, such as raspberry bushy dwarf virus, may lead to symp-toms of crumbly fruit.

17

It takes about 30 to 35 days for raspberry fruit to mature after pollination.Individual fruit typically weigh from 2.5 to 5 g, depending on the cultivar.For maximum productivity, flavor, and sweetness, fruit must reach full matu-rity and full size before harvest. However, fruit firmness decreases in thelater stages of fruit maturation. Fruit firmness is also cultivar dependent.

The “berry” is an aggregate fruit consisting of many drupelets, each ofwhich contains a pyrene (seed). The drupelets are spirally arranged arounda white-colored receptacle. When picked, the berry separates from the recep-tacle, or “torus,” yielding a hollow, thimble-shaped fruit. The ease of fruitremoval when ripe is cultivar dependent, with those suited for machineharvesting requiring easy fruit removal.

1.3.2.2 Blackberry

Blackberries are often classified according to their cane architecture into threetypes: erect, semierect, and trailing.27 Erect blackberries produce primocanes



from buds at the base of floricanes at the crown or from buds on roots,whereas trailing and semierect types only produce new primocanes frombuds on the crown. With the exception of the primocane fruiting erect types,primocanes are vegetative the first year and fruit the second year on theentire length of the floricane.

Blackberries have an extensive root system. Primocanes emerge in thespring, with rapid growth under suitable temperature conditions. Erect andsemierect blackberries produce primocanes that grow upright, with vigordependent on the cultivar and growing conditions. The primocanes of trail-ing blackberry are not self-supporting and will grow along the ground. Caneswill continue to grow in length until cold weather in the fall limits theirdevelopment.

In general, flower bud initiation in blackberry occurs under short daylength and low temperature. However, the time of flower bud initiation andthe pattern of development on the cane can vary with the growing locationand the blackberry type or cultivar.28,29 Primocane fruiting blackberries pro-duce fruit on the top one-fifth or so of the cane during the latter part of thegrowing season.

The chilling requirement of blackberries has been reported to range from200 to more than 900 hours, depending on the type and cultivar.30,31 Weather,specifically low winter temperatures, limits where blackberries can begrown.32 In general, erect blackberries can survive much lower winter tem-peratures (less than 5°F) than trailing types, and thorny cultivars are morewinter hardy than thornless types.33

Blackberry flowers and fruit have a similar morphology to raspberries.The “berry” is an aggregate fruit consisting of many drupelets, each of whichcontains a pyrene (seed). The pyrenes of most trailing blackberries are muchsmaller or thinner than those of erect and semierect blackberry. In all black-berry fruit, the receptacle or “torus” separates from the plant when pickedand is part of the fruit that is consumed. The ease of fruit removal whenripe is cultivar dependent, with those suited for machine harvesting requir-ing easy fruit removal.

It takes from 40 to 60 days for blackberry fruit to mature after pollination.Individual fruit typically weigh from 3 to 12 g, depending on the cultivar.Many blackberry fruit are not at their optimum flavor until they change fromglossy black to dull black in color. For maximum productivity, flavor, andsweetness, fruit must reach full maturity and full size before harvest. How-ever, fruit firmness decreases in the later stages of fruit maturation. Fruitfirmness is also cultivar dependent.

1.3.2.3 Raspberry-blackberry hybridsHybrids of red raspberry and blackberry are grown commercially. These areconsidered trailing blackberry types due to their growth habit. While Boysenand Logan have historically been very important commercially, the acreageof these, particularly Logan, has declined over the last 10 years. Otherhybrids that are occasionally sold include Tayberry and Tummelberry.



1.3.3 Blueberry

There are about 400 species of blueberry (Vaccinium sp., family Ericaceae).The most important blueberries cultivated worldwide are the northern high-bush (V. corymbosum), southern highbush (complex hybrids based largelyon V. corymbosum and V. darrowi Camp.), and rabbiteye blueberry (V. asheiReade), all native to eastern North America.34 The lowbush blueberry innortheastern North America (mainly V. angustifolium) is harvested frommanaged native stands. Various other species are harvested from the wildin many regions of the world. Like other ericaceous plants, blueberriesthrive in acid soils with a pH between 4.2 and 5.5. All commercial blueberryspecies are deciduous and have a typical bush height at maturity of 1 footin lowbush blueberry, 6 to 8 feet in highbush, and 12 feet in rabbiteyeblueberry.

The roots of highbush and rabbiteye blueberries are very fine, fibrous,and lack root hairs.35 Lowbush blueberries produce roots adventitiously fromrhizomes, or below-ground stems. Thus lowbush blueberries are maintainedin solid beds without aisles, whereas highbush and rabbiteye types areplanted in fields with aisles between rows of plants. The fine, fibrous rootsof the blueberry require an open, porous soil. Most blueberry roots are foundwithin the drip line of the bush and in the upper 18 inches of soil.

Blueberries produce simple buds—vegetative buds, producing a leafyshoot, and flower buds, producing only an inflorescence. Flower buds arelarge and almost spherical, whereas vegetative buds are pointed, small, andscalelike. Buds are found mainly on 1-year-old wood, with latent buds alsooccurring on older wood. Shoot growth occurs in two or more flushes perseason, depending on the cultivar and the length of the growing season. Theimpact of light intensity and temperature on blueberry plant growth is wellreviewed by Darnell.14

New canes develop from the crown (base) of the blueberry plant in earlyspring or from older wood higher up in the bush. These shoots, usuallycalled “whips,” are extremely vigorous and often are the “renewal” woodfor subsequent years’ production.

Flower bud initiation occurs under short day length in late summer andearly fall,36,37 usually on the tip of the current season’s shoot. Initiationproceeds basipetally, with the number of floral buds per shoot affected bythe cultivar, climate, and production practices. Flower bud developmentcontinues until temperatures become too cool in fall. Both flower and veg-etative buds require a period of dormancy, from 800 to 1200 hours between32°F and 45°F in northern highbush blueberries, before growth begins againthe following spring.15 However, flower bud differentiation in southern high-bush blueberries may occur through the winter without a dormant period.38

Blueberry plants flower in spring, with flowers at the tip of 1-year-oldwood and the tip of the cluster opening first. The length of the bloom periodvaries with the cultivar, but can be affected by climate. Each flower budcontains from 8 to 16 potential flowers.15 Flowers consist of sepals (calyx),



petals (a four- or five-lobed, urn-shaped corolla), 10 stamens, and a pistil.39

Commercial growers usually use honeybees for pollination. Although blue-berries are often self-fertile, cross-pollination increases fruit set and fruit sizefor many cultivars.40–42

The blueberry fruit is a true berry, consisting of an ovary with up to 100 seeds.The fruit of some species, particularly rabbiteye blueberries, contain stonecells, that contribute to fruit grittiness.14 Ripe fruit are generally blue,blue-black, or purple in color, but have a surface wax layer, the “bloom,”which may make the berry appear lighter in color.

The fruit development period ranges from 42 to 90 days for northernhighbush,43 55 to 60 days for southern highbush,44 70 to 90 days for low-bush,45 and 60 to 135 days for rabbiteye blueberry,46 depending on the cul-tivar, weather, and plant vigor. The sugar content of the fruit will increaseduring maturation to about 15% when the fruit is ripe. Fruit size continuesto increase after the fruit turns blue, due mainly to water uptake. Individualfruit typically weigh from 0.5 to 3 g, depending on the cultivar. Fruit flavor,much of it associated with the skin, increases during ripening, but not afterharvest.

1.3.4 Cranberry

The large-fruited American cranberry (V. macrocarpon, family Ericaceae) is alow-growing, trailing, woody, broadleaf, nondeciduous vine. This species ofcranberry is native to eastern North America. The small-fruited cranberry(V. oxycoccos) is not commercially cultivated in North America, but is har-vested in eastern Europe and Asia. Like blueberries, cranberries are adaptedto acid soils and are best grown at a pH of 4.2 to 5.5.

Cranberry roots are very fine, fibrous, and lack root hairs. Roots arereadily formed on decumbent stems when covered with a moist mediumsuch as sand. Plants produce various types of shoots. Runners are horizontalstems ranging from 1 to 6 feet in length and spread profusely over the bedor canopy. The short, vertical branches in cranberry are called uprights.Uprights originate from axillary buds on the runners or from older uprightsand grow for several years. Uprights are typically 2 to 3 inches long, butlength is affected by light intensity and nutrition. Uprights can be eitherfruiting or vegetative (nonfruiting). In the Pacific Northwest, from 150 to700 uprights per square foot have been documented in Stevens cranberrybeds, with 10% to 65% of these being fruiting uprights.

Cranberry uprights produce one of two types of buds at their tip: flow-ering (fruit) and vegetative. Flower buds may contain from one to sevenflowers, as well as leaves and a growing point. Axillary buds located at aleaf node either on the runner or on an upright are the source of new uprightsor runners.

Bud break in cranberry typically occurs in early April, depending onweather conditions and vine nutrition. In April and May, some vegetativegrowth, including the development of new leaves, occurs. At the “hook”



stage, the flower pedicels are visible on fruiting uprights. At this stage, thecurve of the slender flower stem with the still-closed flower is said to resem-ble the neck and head of a crane, thus suggesting the name “craneberry,”which was shortened to cranberry. Bloom begins around the first part ofJune and lasts from 3 to 6 weeks, depending on the growing region.

Each flower is borne individually, with one to seven flowers per upright.Normally, vegetative growth continues beyond the flowers. The normalflower consists of an inferior ovary with four cells, a calyx of four sepals,and a corolla of four petals that are pinkish white in color and deeply cleft.Eight stamens surround the pistil.47

The cranberry is self-fertile, however, some evidence indicates thatcross-pollination may improve fruit set and berry size. Mixtures of cranberrycultivars, or off-types, are not unusual in commercial beds, although this isnot desired from a management perspective. Honeybees are used for polli-nation in commercial plantings.

The ovary and calyx fuse to form a true berry that varies in shape andcolor. The berry consists of a relatively thin epidermis and four loculescontaining from 0 to 50 seeds, depending on seed set. A waxy cuticle coversthe epidermis and contributes to the ability of the cranberry to resist moistureloss after harvest. Although the thickness of this waxy cuticle has been foundto differ among cultivars, it is not related to the keeping quality of the fruit.A typical fruit weight is about 1 to 1.5 g.

Cranberry fruit go through several stages of color development, from greento white to red. Berries reach physiological maturity about 80 days after fruitset. After harvest, the cranberry vine enters dormancy and requires more than1000 hours of chilling before normal growth resumes the following spring.


There are about 150 species of gooseberries and currants (Ribes sp., familyGrossulariaceae) worldwide; approximately 18 of these have been used todevelop modern cultivars. In addition to several species that have ornamen-tal landscape value, five subgenera of Ribes are grown for their fruit: blackcurrants (R. nigrum), red currants (R. rubrum), white currants (variants ofR. rubrum), gooseberries (R. uva-crispa), and jostaberries (Ribes × nidigrolariaBauer), hybrids of black currants and gooseberries.8

Cultivated gooseberries and currants are woody, perennial, deciduousshrubs that normally grow from 3 to 5 feet tall. Jostaberries can grow to8 feet tall. Plants develop root systems about 3 feet in diameter, with mostof the roots in the top 16 inches of soil. Roots near the surface are especiallyabundant in root hairs.

Ribes produce simple buds, either vegetative or floral. Vegetative budsproduce short shoots—spurs—in all except black currants, or longer shootsthat have strong apical dominance, particularly in currants. Vigorous newshoots also originate from the base of the plant, providing an importantsource of renewal wood for future production. Leaves, arranged alternately



along shoots, are lobed and are high in phenolic and terpenoid compounds.Black currant leaves and buds are used as medicinal herbs.48

Flower bud initiation for most Ribes occurs with short days and cooltemperatures. Flower bud development is completed about 7 to 10 daysbefore the flowers open. In black currants, flower bud development startsat the base of current-season shoots, progressing acropetally. In red and whitecurrants, most jostaberries, and gooseberries, some flower buds are initiatedon current-season shoots, but most are initiated on spurs, located on 1- to3-year-old wood. Thus the flowers of black currants are produced on1-year-old wood, whereas all other Ribes grown commercially produce flowersmainly on spurs of 2-year-old or older wood—this affects pruning practices.

Once canes enter full dormancy, they must go through a period ofchilling—800 to 1600 hours—before growth can resume the following spring.Gooseberries and currants are among the most cold hardy fruit crops, toler-ating −22°F to −31°F when fully dormant.

Currants and gooseberries can bloom early, making them susceptible tofrost damage in northern production areas. Currants produce flowers onracemose inflorescences called “strigs.” Gooseberry and jostaberry flowersare borne in clusters of one to three, sometimes called fascicles. Ribes flowersare greenish yellow or red and are pollinated by bees and other insects.Although most red and white currants and gooseberries are consideredself-fruiting, some black currant cultivars are considered partially or com-pletely self-sterile. The degree of self-fertility may differ with the cultivar,growing region, and perhaps other factors. Thus many recommend plantinga pollinizer in commercial black currants.8

Red and white currant berries have a thin epidermis that tears when thefruit is picked from the pedicel. Thus these crops are harvested by pickingthe entire strig when all the berries are ripe. Black currants are more firmand can be stripped from the strig as individual fruit or entire clusters canbe picked by hand.


1.3.6.1 LingonberryLingonberries (Vaccinium vitis-idaea L.) belong to the family Ericaceae and arethus closely related to blueberries and cranberries. Lingonberries are native tothe circumpolar boreal region, including Scandinavia, Europe, Alaska, andnorthern Canada, but are not widely cultivated. The lingonberry is known bymany other common names, including lingon, alpine cranberry, dry-groundcranberry, foxberry, moss cranberry, mountain cranberry, northern mountaincranberry, cowberry, partridgeberry, red whortleberry, and rock cranberry.

Lingonberry is a low-growing, woody, perennial, evergreen plant thatspreads by below-ground stems called rhizomes. Plants are typically 1 foottall and produce urn-shaped, white or pink flowers. Flower morphology issimilar to that of the blueberry. The fruit is a small, red berry ranging from0.17 to 0.45 g in size.



Lingonberries flower on 1-year-old wood, similar to blueberries. How-ever, lingonberries are native to areas with very short summers, and whenthey are grown in environments with longer summers, some cultivars willhave two bloom periods, March to April and July to August, with twopotential fruit harvest seasons. A pollinizing cultivar is required for fruit setand good fruit production.

1.3.6.2 Hardy kiwifruitHardy kiwifruit are vining, cold hardy plants native to China, Russia, andJapan. Ananasnaya is the most widely grown cultivar of hardy kiwifruit[A. arguta (Siebold & Zucc.) Planch. ex Miq] in the world.

The mature plant is very midwinter hardy, tolerating temperatures of30°F. However, Ananasnaya has a relatively low chilling requirement andmay be injured due to fluctuating temperatures in late winter or early spring.

The flowers of Ananasnaya are small, less than 1/2 inch in diameter,and are female, bearing a multibranched stigma and nonfunctional stamens.The flowering period lasts for about 10 days. The flowers of Ananasnayamust be cross-pollinated for successful fruit production. Male selections ofA. arguta can serve as pollinizers. Male selections of A. deliciosa (A. Chev.)C.F. Liang & A.R. Ferguson may also be used as pollinizers, but they are notconsidered sufficiently cold hardy to be recommended as males for commer-cial plantings in northern temperate areas.49

Flower bud initiation in hardy kiwifruit occurs the year before floweringas day length shortens. Flowers are borne in leaf axils either singly or morecommonly as three flowers in a small cyme on shoots from 1-year-old canes.

The fruit of Ananasnaya is a medium size, ovoid, 1.5 inches long × 1 inchwide berry. Fruit weight ranges from 2 to 14 g, averaging about 7 g perfruit.50 Ananasnaya produces a green to red blushed berry with a smooth,edible epidermis. The smooth skin is bright green on immature fruit anddevelops a red blush later in the maturation phase, particularly insun-exposed fruit, with the green color darkening and the fruit softening asit ripens. The flesh is light green, juicy, and has a sweet-tart taste with a rich,aromatic flavor that has been compared to ripe pineapple, strawberries,bananas, European gooseberries, overripe pears, or rhubarb. Fruit mature inlate summer to autumn, 100 to 110 days after flowering, depending on theregion, with firmness decreasing in the later stages of ripening.49,51

1.4 Berry crop production systemsBerry crops are grown in various types of perennial and annual productionsystems. Typical production methods are briefly described below for eachberry crop, with major variations by production region mentioned.

In most studies involving berry crops, experimental treatment effects onfruit quality have generally been described as changes in fruit size or weight,uniformity of shape, color, fruit firmness, texture, percent soluble solids (°Brix),pH, titratable acidity, and anthocyanins. These fruit quality attributes and yield



can be affected by disease, insufficient or excess irrigation (or rain), nutrientdeficiency or excess fertilization, poor pollination/fertilization, and fruit expo-sure to light. There is now considerable interest in identifying whether culturalpractices, beyond cultivar selection, can impact the beneficial health propertiesof berry crops. The first step is identifying which compounds are most impor-tant in each crop. Then research is required to see how much these attributesare affected by cultural practices such as pruning/training, irrigation, fertili-zation/plant nutrition, production in tunnels, etc. We may thus see additionalfruit quality attributes described in future research. However, to date, therehas been relatively little published research on the impacts of cultural practiceon the nutraceutical properties of fruit.

In general, most fruit for the fresh market is harvested directly into thefinal container, often clear plastic clamshells. Flats are usually supported onspecially constructed wire or wooden stands and are not allowed to contactthe ground. Pickers are monitored to ensure high quality. In ideal situations,fruit is harvested in the early morning, after the dew is off the berries andtemperatures are cooler, for best quality.

Field heat is often removed using forced-air cooling, where large,high-powered fans pull cold air through pallets of fruit to lower fruit tem-perature to 32°F to 34°F within 2 hours of picking. Relative humidity withinthe refrigerated rooms is maintained at 85% to 95%, although free moistureon the berries or in the containers must be kept to a minimum. Unlike someother fruits, fresh market berries are not washed or cooled in water (hydro-cooling) after picking and before shipment to consumers. To reduce fruit rot,the berries must be kept dry.

It is not possible to cover production systems for all berry crops in greatdetail in this chapter. There are general textbooks on berry crops,52 blueber-ries,15,53,54 raspberries and blackberries,32 strawberries,55 cranberries,16 andgooseberries and currants.8 Nitrogen fertilization recommendations are notprovided here, but can be found in various local publications.56–59 Pest prob-lems and suggestions for management are not covered here, but are wellreviewed in other publications.8,12,17,18

1.4.1 Strawberry

Strawberries are grown in annual or perennial production systems in thefield or are planted in soilless media in tunnels or greenhouses to target“off-season” markets.

1.4.1.1 Annual production systemsMost of the strawberry acreage worldwide is planted in the annual hillproduction system. In this system, strawberries are planted and cultivated,fruit is harvested, and the plantings are removed annually. Many of the cul-tivars grown worldwide were bred in public or private breeding programs inCalifornia. Common short-day cultivars include Camarosa, StrawberryFestival, Elsanta, Darselect, Marmolada, Addie, Korona, and Honeoye.



Common day-neutral cultivars include Diamante, Albion, Seascape, andSelva. There are also proprietary cultivars grown in annual production sys-tems. The cultivars grown can shift relatively quickly compared to otherberry crops, as there are many breeding programs worldwide producingcultivars for annual production. As growers try to remain competitive withnewer, better cultivars, plantings are changed annually.

The annual strawberry production system is rather complex, with manyvariations. Plantings are established with fresh-dug plants, partially or fullychilled dormant plants, or plug plants. Dormant plants can be stored for1 to 9 months at 32°F to 34°F and are commonly used in off-season productionsystems. Planting dates vary from summer through winter. By altering theuse of short-day and day-neutral cultivars, the amount of chilling, and theplanting date, growers are able to produce fruit 11 months of the year inCalifornia, for example. Late fall to winter planting of fresh, short-day nurs-ery plants (fresh dug or partially chilled in cold storage) for late winterthrough early summer fruit production is the dominant cultural practiceworldwide. Summer planting, using cold-stored (“frigo”), short-day plants,is used to a more limited extent to extend the season. For example, largecold-stored plants can be planted in sequence from April until mid-July, withfruiting starting about 8 weeks after planting. Production in the summer isalso achieved by planting day-neutral cultivars (e.g., Selva) in the spring,with fruit harvest from July to October. Growers in all production areas withmild winters are thus able to target higher priced fresh market niches.

Typically, annual strawberries are grown on raised beds covered withplastic, with fumigation occurring prior to planting. Drip irrigation, underthe plastic, is typical. Fertilization through the drip system is common. Plantsgrown in annual production systems, particularly on sandy soil, benefit fromfertilization with nitrogen. Plants are often established in a double-row hillsystem, with plants spaced 8 to 12 inches apart and the double-row centers36 to 40 inches apart. Runners are removed every few weeks to keep plantsas individuals and to encourage good fruit production and ease of harvest.

The fruit is picked by hand for the fresh market or processing. Theaverage yield per acre ranges from 12 to 45 tons, depending on the plantingdate, cultivar, and production region.

1.4.1.2 Protected culture systemsIn the last decade, there has been a considerable increase in programmedout-of-season production systems in several European countries. This isbeing accomplished, in part, by using several cultivars with different fruitingseasons, but mainly by sequential planting in the field of cold-stored plants(described above) and by growing strawberries in plastic-covered tunnelsand in greenhouses. Tunnels can be used to protect a day-neutral cultivarfrom adverse weather; in this way, fruit harvest can continue well into theautumn. Protection of the crop from rain, wind, and hail improves the easeof fruit harvest and fruit quality. Often, domestic strawberries bring pre-mium prices early and late in the season compared to imports.



Production in tunnels and greenhouses requires a higher investment ofcapital, and more skill and technical knowledge from growers. There aremore than 32,000 acres of strawberries grown in tunnels worldwide, muchof them in Europe, particularly in Spain. On a large proportion of thisacreage, strawberries are grown in soil using the traditional annual produc-tion systems described above. Growing strawberries in tunnels can advancethe harvest by 3 weeks compared to an unprotected crop. Additional heatingcan advance the crop further and allow harvest long into the autumn. Sub-strate (no soil) culture is used on a small scale in tunnel and greenhouseproduction systems.

There are about 500 acres of strawberry greenhouses in Belgium and 270 acresin The Netherlands.60 The most common cultivars are Elsanta, Lambada,Darselect, and Gariguette. There are smaller areas of greenhouse productionin France, the United Kingdom, and Switzerland. In substrate culture, straw-berry plants are grown in buckets, bags, and containers filled with a peatmixture, pine bark, and perlite or on rock wool slabs. In Belgium and TheNetherlands, two or three crops can be harvested in greenhouses per year.Sophisticated computerized irrigation/fertilization (fertigation) systems andclimate control, carbon dioxide (CO2) enrichment, and artificial lighting arecommon cultural techniques. Containers filled with strawberry plants areplaced in the greenhouse in November at a plant density of about one persquare foot. Fruit harvest is from late winter through spring, depending onthe cultivar, with a yield ranging from 0.5 to 1.2 pounds per square foot. Asecond planting can go in the greenhouse after the first planting’s harvestis done, and a third is also possible.

1.4.1.3 Perennial production systemsIn perennial production, short-day cultivars most commonly are grown inflat or raised-bed systems in the open field using mainly “matted rows.”Plantings are established in the spring, with the first major fruiting seasonbeing the year after planting, from June to August, depending on the pro-duction region. Plantings are kept for 3 to 5 years. Perennial production isthe most common system in Scandinavia, Poland, the northwest and north-east United States, and Canada. Common cultivars include Senga Sengana(Scandinavia, Poland), Korona and Jonsok (Scandinavia), Honeoye (Scandi-navia and the eastern United States), Totem (western North America), andAllstar, Earliglow, Glooscap, and Jewel (eastern North America). Cultivarssuited to perennial production systems must runner well, have good winterhardiness (particularly in more northern climates), and have higher levels ofresistance to specific pests and diseases than those grown in annual systems.Cultivars tend to be adapted to the region in which they were developed.

Plants are typically set at relatively low densities (8,000 to 20,000 plantsper acre) in spring using dormant, cold-stored plants, and matted rows arecreated when the runner plants root and fill in the row. Aisles are maintainedusing cultivation. The year after planting, the original “mother” plants andwell-rooted daughter plants (runners) flower and fruit. Matted rows typically



produce yields of 5 to 12 tons per acre, depending on the cultivar, fruitingseason, and production region. The yield and berry size decline, primarilydue to infection by viruses, as plantings age from the first through the thirdfruiting season. For processing, berries are picked in the early morning.Cultivars ideal for processed markets can be picked without the cap or calyx.

Plantings are irrigated using overhead sprinkler systems or drip irriga-tion. Weed management is very important to maintain good plant growthand fruit production.

Strawberries are renovated after each fruiting season to prepare for nextyear’s crop. Renovation includes mowing off the foliage of short-day culti-vars (to stimulate faster regrowth), weed management, narrowing of mattedrows, fertilization, and irrigation. In colder climates, straw mulch is appliedto the top of matted rows in winter to protect plants against cold injury. Inall production regions, overhead irrigation is used to protect flowers againstfrost injury in the spring. Growers with drip irrigation systems can use rowcovers for frost protection.

1.4.2 Raspberry

Raspberries are most commonly grown in perennial production systems thatgenerally have a life of 10 to 20 years for red raspberries and 5 to 10 yearsfor black raspberries. Red raspberries are also forced in tunnels for off-seasonproduction. Fresh market raspberries can be stored for 2 to 3 weeks usingcontrolled atmosphere storage.

The best soils for raspberry production are deep and well-drained, witha sandy to loamy texture and a pH between 5.6 and 6.5. The most commonplanting stock used is dormant, bare-root, certified, disease-free plants ortissue-cultured plants. Rows are run in a north-south direction to maximizecanopy light exposure.

1.4.2.1 Summer-bearing red raspberryThe largest share of red raspberry acreage worldwide is planted to summer-bearing types. Most of the raspberry acreage in northwestern North Americaand Serbia is planted with Meeker, as well as about 8% of the acreage inChile. Meeker is well suited for processing, as is Willamette. Fresh marketcultivars grown worldwide include Tulameen, Glen Ample, Glen Lyon,Chilliwack, and some proprietary cultivars.

Summer-bearing red raspberries can be grown in either hedgerows orhill systems. In mature hedgerows, individual plants are not distinguishablebecause canes run continuously down a row. Hedgerows are best establishedby planting rooted plants or root cuttings about 2 feet apart in rows spaced10 feet apart. The hedgerow width, 1 foot, is maintained through handpruning, mowing, or rototilling along the row edge. Overly dense canopiesincrease pest and disease problems and can reduce flower bud developmentdue to shading. Hedgerow systems are common in hand-harvested fields orplantings that are for U-pick or direct markets. However, hill systems are



much more common in machine-harvested fields and larger commercialplantings for the fresh market. A trellis is required to support the floricanesand primocanes. The most common trellis used has two moveable lowerwires at about 2.5 to 3 feet high to train new primocanes and two top wiresat 5.5 to 6 feet to “pinch” the floricanes or keep them trapped in the rowwhen they are fruiting. Generally canes are not tied to the wires in winter.

In hill systems, individual plants can be distinguished. Plantings aregenerally established with 2.5 feet between plants in the row and 10 feetbetween rows on raised beds or flat ground. The overwintering canes aretrained by tying them together in bundles and tying them to a trellis asdescribed above. The bundled canes are topped at 6 feet or are left untoppedand are arched and tied to the trellis. Topping canes reduces yield, but canincrease average fruit size by 10% depending on the cultivar.61

In general, summer-bearing raspberries are pruned by removing thedead floricanes anytime from after fruit harvest through autumn. Theremaining primocanes are thinned in some production systems to a certainnumber per foot of row or per hill, weak or diseased canes are removed,and the remaining canes are trained to the trellis, as described above. Theprunings are typically left in the field, between rows, and are flailed orchopped. Thus the nitrogen in the prunings will ultimately be returned tothe plant system.62

In some production systems, growers practice primocane suppression(also called cane burning), where the first flush of new primocanes is cut offor chemically suppressed when primocanes are about 6 inches tall. Thesubsequent flush of canes is then retained for next year’s crop. This practiceis only used in vigorous cultivars and has the benefits of improving thecurrent season’s yield of floricanes, machine-harvest efficiency, and nextyear’s yield.

Plantings are irrigated with overhead or drip systems, depending on theproduction region. Growers commonly fertilize through drip systems. Weedsare usually managed using herbicides, with diseases and insects controlledas needed or with preventative pesticide applications.

The impact of nitrogen fertilization on growth, yield, and fruit qualityof raspberries has been reviewed.62 The nitrogen concentration of ripe fruitof fertilized plants ranges from 1.4% to 1.7%.63 In a 5-year study, nitrogenfertilization decreased the total soluble solids of red raspberry fruit.64 Thereare no conclusive data on the impact of the nitrogen fertilization rate on fruitnitrogen concentration and any related impacts on fruit quality.

The harvest season for summer-bearing types grown in open fields lastsfor about 3 to 8 weeks, depending on the production region and cultivar.For example, in Oregon, the season for Meeker is from about June 20 to July 20.Raspberries are fragile, have a short shelf life, and the berries ripen overseveral weeks, so frequent harvests are necessary. Once picked, the berriesmust be kept as cool as possible and transported quickly to processors orrefrigerated facilities to prepare them for processing or fresh packaging andshipment.



About 90% of the red raspberry acreage for processing in North Americais harvested by machine. In contrast, only 5% of the Chilean acreage, alsofor processing, is harvested by machine. This difference can mainly be attrib-uted to labor costs. In North America, labor for hand harvesting can be hardto obtain and is relatively expensive. Hand harvesting can account for up totwo-thirds of the total labor cost of fruit production. A typical mechanicalharvester with one operator and four field graders can do the work of 80 to85 people hand harvesting.

Aside from decreased labor costs, mechanical harvesting has other advan-tages. Machine harvesters can be operated at night when hand picking is notpractical. The lower night temperatures help keep fruit quality high. Com-pared with hand-harvested fruit, machine-harvested raspberries may also bemore uniformly ripe. This translates into berries that are larger, with bettercolor, lower acidity, and higher total soluble solids—ideal for processing.

However, there are some important considerations with mechanical har-vesting:

• Mechanical harvesters are expensive to purchase and maintain.• Row spacing and trellises must be designed for machine harvesting.• Alleys must be maintained so as to support the harvester’s wheels

without excessive compaction.• Irrigation must be managed so as to avoid creating muddy alleys

that could interfere with harvester movement and operation.• Cultivars must be suited to mechanical harvesting; insect manage-

ment is critical, as even beneficial insects that end up in the harvestedproduct are a contaminant.

• Mechanically harvested raspberries are not suited for the fresh market.

A variety of mechanical harvesters are commercially available, althoughmost are self-propelled, over-the-row machines. Rows of flexible horizontalbars or “fingers” on each side of the crop row gently shake the fruitinglaterals, trellis wires, and canes, causing the ripe fruit to drop off. Inclinedcatch plates about 12 to 15 inches above the ground collect the falling fruit.From the plates, the berries travel on conveyor belts across screens wherefans remove some contaminants. The fruit is then carried across a shortinspection belt, where graders remove additional contaminants, and theninto flats or other containers. Harvesters usually travel at about 1 mile perhour down the row.

Summer-bearing red raspberries are machine harvested every 2 to 3 daysto minimize the loss of ripe fruit. Thus there may be 10 to 15 harvests perseason, depending on the cultivar and climate. Waiting too long betweenharvests increases fruit losses on the ground. Research has shown that typicallosses for machine harvesting are 16% of the total yield over the length ofthe season.61 There are also losses when raspberries are hand picked—manyestimate these to be 5% to 10% of the total yield.

Hand harvesting is common on small farms and larger operations thatfocus on high-quality, fresh market fruit or high-quality IQF fruit for



processing. The picking interval varies with the stage of harvest, cultivar,and weather conditions. Five or 6 days may pass between the first and secondpickings, with 2 to 3 days being more common during the peak of the seasonor warmer temperatures. However, in some regions, such as Chile, fruit forthe fresh market is hand harvested before it is fully mature—this underripefruit is more firm and can be more easily shipped to distant fresh markets.Fruit that is not considered ideal for the fresh market is processed. In Chile,they often harvest daily and on some farms, twice a day.

The average yield of summer-bearing raspberries is from 2.5 to 4.5 tonsper acre, but this varies greatly with the cultivar, growing region, and methodof harvest.

1.4.2.2 Primocane fruiting raspberryThere are many primocane fruiting raspberry cultivars grown worldwide.The red-fruited Heritage, however, accounts for 82% of the total acreage inChile (more than 21,000 acres) and a significant portion of the primocaneacreage in North America. Other primocane fruiting cultivars grown, inaddition to many proprietary cultivars, are Polka, Josephine, Caroline,Autumn Bliss, Amity, and Anne (yellow).

Primocane fruiting raspberries are typically grown in hedgerows thatare maintained to a width of 1 to 1.5 feet. This type of raspberry can bemanaged to produce one or two crops per year—an early crop on the baseof the floricane and a later crop on the tip of the primocane. The portion ofthe primocane that fruited in late summer/fall dies in the winter. This canecan be pruned to remove the dead portion and it will fruit the followingyear on its base (floricane) early in the summer, at about the same time as asummer-bearing type. These floricanes die after harvest and are removedduring dormant pruning. Primocane fruiting raspberries can easily be grownto produce just a primocane crop by mowing all the canes to about 1 to 2inches high in late winter. New primocanes emerge in spring, flower insummer, and fruit in late summer, producing one crop per year. In Chile,most Heritage plantings are managed to produce both types of crops. Insome warm climates, the primocanes are summer pruned to affect the har-vest season.

Primocane fruiting raspberries can be grown free standing, but are oftensupported on a simple trellis to keep the canes from bowing out into thealleys. Plantings are irrigated and otherwise maintained similarly to thosementioned for summer-bearing raspberry. Average yield tends to be lower,2 to 4 tons per acre, and almost all are hand harvested for the fresh marketor processing.

1.4.2.3 Off-season production systemsCovers, often polyethylene, are used in many production regions to protectfruit from the weather and thus maintain quality. Shade cloth is also usedfor this purpose, as fruit exposed to high ultraviolet light levels can be lessfirm and may develop white drupelets. Shade cloth can also be used to delay



the fruiting season somewhat, depending on when it is applied. The fruitingseason of field-grown floricane fruiting types can be advanced and pri-mocane fruiting types extended using polyethylene-covered tunnels.

Specialized off-season production systems have been developed to targetspecific, high-value fresh markets. Plants are established in soil under hightunnels or in pots for use in tunnels or greenhouses. In floricane fruitingcultivars, special nurseries produce “long-cane” raspberries. These nurseryplants consist of a rooted floricane, 3 to 5 feet long, that has been exposedto the right conditions for good flower bud set and has received adequatechilling to satisfy dormancy requirements. High-density plantings (about12,000 canes per acre) are staggered to target specific fresh fruit marketingseasons, similar to what was described for off-season strawberry productionsystems.

1.4.2.4 Black raspberryThe most common cultivar grown is Munger, which accounts for almost allof the acreage in Oregon. Plantings of black raspberries (also called “black-caps”) are established in spring using plants produced by tip-layering ortissue culture. Plants are usually placed 2.5 to 3 feet apart in rows with 10 feetbetween rows. Although black raspberries can be grown without a trellis,an inexpensive support structure of some kind, such as metal posts withtwine running on each side of the row, is commonly used in Oregon.

Black raspberries are summer pruned to tip the new primocanes to aheight of 2 to 3 feet to encourage branching. In winter, plantings are typicallypruned by machine to shorten the primocane branches. This is done usingtractor-mounted sickle bars that run along the top and one side of each row.Some branches are thus pruned shorter than others. However, this systemis inexpensive and still produces good quality fruit for processing. Thefloricanes fruit in early summer, generally with a 4-week fruiting season.After fruit harvest, the floricanes die. Growers may remove dead floricaneswhen pruning in winter; however, most growers in Oregon leave the deadfloricanes in the row, as they eventually break off at the soil level and fallinto the aisles.

Fruit is sometimes harvested by hand for processing markets and forlocal fresh markets, but harvesting by machine, similar to that described forred raspberry, is most common. Fruit is harvested in two to three pickings,with a total average yield of 1.5 tons per acre being common. Fruit is takenvery quickly from the field to the processing plant.

Purple raspberries are grown to a very limited extent, mainly for localprocessed markets. This type of raspberry is grown similar to black raspberry.

1.4.3 Blackberry

Blackberry plantings generally have a life of 15 to 20 years. Plantings areestablished in the spring using plants propagated by tissue culture or rootcuttings, depending on the type of blackberry. Blackberries are tolerant of a



wide range of soil pH (4.5 to 7.5) and soil types, although growth is betterwhen soil drainage is good. Rows are usually planted in a north-southdirection to maximize canopy exposure to light.

The impact of nitrogen fertilization on growth, yield, and fruit qualityof blackberries has been reviewed.62 The nitrogen concentration of ripe fruitfrom fertilized plants ranges from 1.4% to 1.6%. The nitrogen fertilizationrate had little effect on fruit pH, titratable acidity, and soluble solids inThornless Evergreen and had no consistent effect on fruit firmness.65 InArapaho, increasing nitrogen fertilization rates increased fruit nitrogen con-centrations and pH, but had no effect on the percent soluble solids, titratableacidity, and sugar:acid ratio.66 Fruit are a strong sink for fertilizer nitrogen.67,68

There are no conclusive data on the impact of nitrogen fertilization rate onfruit nitrogen concentration and any related impacts on fruit quality.

Most blackberries are grown using a combination of cultivation andherbicides for weed management and pesticides for disease and insect con-trol. In 2005, there were 6246 acres grown using organic production systems,mostly in Ecuador and Costa Rica.2

Plastic-covered tunnels are being used on about 775 acres of blackberriesworldwide, mainly to protect against adverse weather.2 Tunnels or green-houses to advance or delay the fruiting season, in addition to protectionagainst the elements, are being used in Spain, The Netherlands, Italy, Roma-nia, and South Africa. The use of tunnels is expected to increase, particularlyin Mexico.

In 2005, 50% of the cultivars grown worldwide were semierect, 25% wereerect, and 25% were trailing types. In general, erect and semierect cultivarsare grown predominantly for the fresh market—these types produce fruit thatis more firm, has a longer shelf-life, and is better suited to shipping. Trailingtypes are mainly used for processing. These cultivars, like Marion, are knownfor having highly flavored, aromatic fruit, with small seeds. The fruit of mosttrailing cultivars available today is not firm enough for long-distance ship-ping. Still, there are a few cultivars of trailing blackberry that are relativelynew and are suited for the fresh market—Siskiyou and Obsidian are.

1.4.3.1 Semierect blackberryThornfree, Loch Ness, and Chester Thornless account for 60% of thesemierect blackberry acreage and Dirksen Thornless, Hull Thornless, andSmoothstem account for 30%. The only other cultivar grown on more than5% of the worldwide semierect acreage is Cacanska Bestrna, grown in Serbia.

The planting density for semierect blackberries varies with the produc-tion region. In Serbia, plants are generally established at an in-row spacingof 3 to 4 feet with 8 to 10 feet between rows. In the United States, plants aretypically placed 5 to 6 feet apart in rows that are 10 to 12 feet apart. In mostfields in China, the planting density is very high, with 1 to 1.5 feet betweenplants and 3 feet between rows.

In almost all regions, primocanes are tipped during the growing seasonat about 5 to 6 feet high to encourage branching. In the winter, the dead



floricanes are removed and the branches of the new canes are pruned toabout 1.5 feet in length or left unpruned. Canes are either trained on amultiple wire trellis with an undivided canopy or are trained to a “double-T”system. In most regions, plantings are irrigated using drip, overhead, ormicrojet systems. However, in China, fields are commonly flood irrigated.

The average yield is 3.5 to 20 tons per acre, with all fruit hand pickedevery 3 to 5 days for the fresh market. The fruiting season in the northernhemisphere ranges from July to October, depending on the cultivar andproduction region. Excess fruit are processed, usually as a seedless puree.Semierect blackberries are considered relatively cold hardy, although coldinjury is still considered the most important production problem in Serbia.In China, canes are buried in winter to avoid cold injury.

1.4.3.2 Erect blackberryBrazos is by far the most common erect blackberry grown worldwide,accounting for almost half of the erect acreage. However, Brazos is rapidlybeing replaced by Tupy in Mexico. Other cultivars accounting for 5% or moreof the erect acreage are Tupy, Navaho, Kiowa, and Cherokee.2

In the more traditional production system for erect blackberries, plantsare established 3 to 4 feet apart in rows 10 feet apart. During the growingseason, primocanes are tipped at a height of 3 to 4 feet, depending on theproduction region, to encourage branching. Growers will go through theplantings on several occasions to catch all of the primocanes. After fruitharvest, or in the winter, dead floricanes are removed by pruning. In someproduction regions, such as Oregon, dead floricanes are left to save laborcosts; they will eventually break off and fall into the rows. In winter, theprimocane branches are usually shortened to about 1.5 feet. In Oregon,however, where hedging primocanes in winter using a machine is common,branch length may vary.

Erect blackberries are grown without a trellis in some regions. However,as the canes are prone to breaking off at the soil level with wind, a trellis issometimes used to support canes and minimize cane loss. Usually a simpletwo- to four-wire trellis is used.

Fruit is harvested by hand, primarily for the fresh market, every 3 to 5 days.The fruiting season of erect floricane fruiting cultivars is about 4 weeks long,from May through July, depending on the production region. Yields rangefrom 3 to 4 tons per acre.

In Mexico, production systems are modified to extend the season forTupy and other erect cultivars. About 5 to 7 months after primocane emer-gence, a chemical defoliant is applied two to three times to induce endodor-mancy. A growth regulator is used about 3 weeks after defoliation to promotebud break. The plants are then pruned. Fruit harvest begins about 90 to 100 daysafter defoliation. After the first crop is finished, many growers prune again,removing the portion of the canes that fruited, and repeat the defoliationprocess to obtain multiple crops. Growers then mow the canes to the groundlevel to repeat the cycle. Often plants are grown in tunnels to protect the



fruit from adverse weather conditions. Using these methods, the Mexicanfruiting season extends from mid-October to June.

A new type of erect blackberry, one that produces a significant crop onthe primocanes, is now available. The first cultivars of this type to be releasedwere Prime-Jan and Prime-Jim. Similar to primocane fruiting raspberry,this type can be grown for a double crop (floricane in early summer plusprimocane in late summer through autumn) or a single crop (primocane only).These blackberries are not yet grown commercially to any significant extent.However, it appears that primocane fruiting blackberries must be tippedduring the growing season for maximum fruit production.69 Primocane fruit-ing blackberries show great promise for improving the availability of freshmarket blackberries worldwide using off-season production systems.

1.4.3.3 Trailing blackberryMarion is the most important trailing blackberry grown, accounting for justover half of the worldwide acreage of trailing types; more than 90% of theMarion acreage is located in Oregon. Other important trailing blackberrycultivars are Boysen, Thornless Evergreen, and Silvan.

Trailing types are typically grown in every-year production systems atan in-row spacing of 3 to 6 feet with 10 feet between rows. Most are grownon trellises, with the canes wrapped around two wires (with the first at 4.5 feetand the top at 6 feet).

Trailing blackberries can be grown in every-year or alternate-year pro-duction systems. In every-year production, new primocanes are trainedalong the ground, under the canopy, while the floricanes are on the wireproducing the current season’s crop. After fruit harvest, the dead floricanesare removed and the primocanes are trained onto the trellis wires in Augustor February. Most growers train primocanes in February, leaving canes moreprotected from cold through most of the winter.

In alternate-year production systems, plants fruit every other year. Inthe “on year,” floricanes produce a crop and primocanes are not managed.In October, the dead floricanes and the primocanes are pruned at the crown.The following “off-year” primocanes are trained to the trellis as they grow.The yield of an alternate-year field is about 85% of an every-year field overa 2-year period.70 Research has demonstrated that primocanes following anoff-year in an alternate-year system are more cold hardy than primocanesthat grew in the presence of floricanes in an every-year system.71,72 There isalso less cane disease in alternate-year production systems than in every-yearsystems. More than 60% of the trailing blackberry acreage in Oregon is grownin alternate-year production systems.

Most of the trailing blackberry production worldwide is processed, withmachine harvesting used on more than 75% of the acreage. The fruitingseason of most trailing cultivars lasts for 4 to 5 weeks, starting in late Juneor early August, depending on the cultivar. Growers begin machine harvest-ing when the primary fruit, those that are first to ripen, are fully mature.Fruit is gently shaken from the plants using the same machine harvesters as



described for red raspberry. However, blackberries are harvested less fre-quently, about every 5 days, depending on the cultivar and temperature,and are typically harvested at night when they are more easily removed.Machine-harvested fruit is more uniform in maturity, having greater aromaand flavor, and higher percent soluble solids than hand-harvested fruit. It ismore difficult to visually distinguish ripeness by color in blackberry than inraspberry. Typical yields range from 4 to 8 tons per acre.

In addition to the possible insect contaminants mentioned for red andblack raspberry, thorns can be a serious contaminant in thorny cultivars thatare machine harvested. Research has helped growers minimize this risk byusing machine harvesters equipped with brushes to remove potential con-taminants.73 Plant breeders consider the development of high-quality, thorn-less trailing blackberry cultivars a high priority and have recently releasedseveral thornless cultivars.

1.4.4 Blueberry

1.4.4.1 Highbush and rabbiteye blueberryNorthern highbush is the main type of blueberry planted in the northernregions of the world. The most common cultivars are Bluecrop, Jersey, Blueray,Rubel, Elliott, Duke, Bluejay, Earliblue, Reka, Draper, Aurora, and Liberty.

Southern highbush blueberries are the most common type planted inwarmer regions of the Northern and Southern Hemispheres. Commonsouthern highbush blueberry cultivars are O’Neal, Bluecrisp, Reveille,Southern Belle, Star, Bladen, Emerald, Jewel, Sharpblue, Misty, Windsor, andJubilee. Ozarkblue and Legacy, with northern highbush in their parentageare commonly planted.

Rabbiteye blueberries are less widely planted than northern or southernhighbush types, but offer a late fruiting season that is an advantage fortargeting key high-priced fresh markets.1 The cultivars Climax, Tifblue,Brightwell, Premier, and Powderblue are common, with Ochlockonee, Alap-aha, Columbus, Maru, and Rahi showing promise.

Blueberries grow best on well-drained soils, high in organic matter, andwith a pH of 4.2 to 5.5. However, in many regions blueberries are successfullygrown through modification of traditional cultural practices. For example,in the relatively new production regions of California and southwesternEurope, blueberries are often grown on sandy soil, with or without organicmaterial incorporated, using acidified irrigation water. In most productionregions, blueberry plants are grown on raised beds about 1 foot in height toimprove soil drainage in the root zone.

Many mature blueberry plantings in North America were established atan in-row spacing of 4 feet with 10 feet between rows. However, long-termresearch experiments conducted in Oregon74,75 and subsequent positive growerexperience have led to a change to higher density plantings worldwide; themost common in-row spacing is now 2.5 to 3 feet with 10 feet between rows.Plantings are established, usually with 2-year-old container-grown plants, but



in many regions with younger plants, in autumn or spring. Organic material,commonly sawdust, is often incorporated prior to planting and applied asa surface mulch after planting; this layer is maintained for the life of theplanting. In some production regions, a weed barrier that is permeable towater or black plastic may be used. However, there are many successfulplantings in which no mulch or weed barrier has been used. Most fieldshave a permanent grass cover in the aisles between rows.

Blueberries are shallow rooted and are thus subject to drought injury.Drought conditions during fruit ripening will reduce fruit size and may affectflavor. A uniform and adequate supply of moisture is essential for optimumplant growth. Water use efficiency is greater in high-density blueberry plant-ings. Water requirements vary by the cultivar, with the greatest need forwater occurring during the fruit development stage.76

Research has shown there is no long-term cumulative yield advantageto producing fruit in the planting year or the year after planting, and in somecultivars there can be a disadvantage to “early cropping.”75 However, somegrowers allow plants to produce fruit earlier than the third year after plantingto recover some of the high plant establishment costs.77 To prevent earlycropping, growers prune the fruit buds at planting and in the dormant periodprior to the second growing season.

Blueberries are pruned annually in most production regions, withseverity varying depending on type of blueberry grown and the amount ofvegetative vigor. In Oregon, unpruned plants had the highest yield after3 years, but also had smaller fruit, a later fruiting season, poorer fruit color(unpublished), and bushes that could not be machine harvested.78 Othershave shown that fruit matures later, with lower percent soluble solids, whenfruit is in shade compared to fruit well exposed to the sun.79,80 Dormantpruning of highbush blueberries is demonstrated in a DVD produced byOregon State University.81 Plants to be machine harvested are pruned to amore upright habit with a narrow crown to allow close fitting of the machineharvester’s catcher plates, thus improving machine-harvesting efficiencyand minimizing fruit loss. For hand harvesting, plants are pruned to main-tain branches within easy picking height and low fruiting branches or canesare removed.

In most northern production regions, highbush blueberries are prunedannually, mainly during the dormant season, with little, if any, summerpruning. Southern highbush blueberries, however, are often pruned afterharvesting by hand or machine (hedging), especially in areas with a longgrowing season. Rabbiteye blueberries are often pruned in summer by tip-ping vigorous shoots on several occasions to stimulate the production offruit buds for next year’s crop.

In North America, most highbush blueberry fruit destined for the pro-cessed market is harvested by machine. A change in the last 10 years hasbeen the increased use of machine harvesting for fresh market fruit; thistrend is expected to continue in most production regions of North Americadue to the high cost and limited availability of labor.



Most of the machine harvesters used are an over-the-row rotary type,similar to what was described for red raspberry. However, blueberry har-vesters tend to be longer to minimize fruit loss on the ground. For fields thatare harvested entirely by machine, losses have been measured as high as24% of total yield in untrellised plantings.74 In many production regions,blueberries that may be harvested by machine are now trellised. Researchhas shown an added recovery of 3% to 8% of total yield when blueberryplants are kept more narrow to fit the “throat” of over-the-row machineharvesters.74 The trellis usually consists of wire posts in the row with twowires, one of each side of the row, that are moved higher as the bushes age.The blueberry plants are not trained or tied to the trellis wires. Trellises areused in some hand-picked fields as well.

With a properly adjusted rotary machine and selection of cultivars, grow-ers may fresh market machine-harvested fruit; however, at present, this fruitis sold to less distant markets, as it has a shorter shelf life than hand-pickedfruit. In many production regions in North America, a large portion of thefruit destined for processed markets is picked by hand. Hand pickers arepaid per pound of fruit harvested.

In other areas of the world, production systems are similar to those in NorthAmerica. However, in Europe and South America, most fruit is hand pickedand the fresh market is dominant. Production on nontraditional substrates andoff-season production in tunnels is quite common in parts of Europe. Not muchis known, at present, about the effect of tunnels on fruit quality.

Cultivated blueberry plants usually require 6 to 8 years to reach fullproduction. Yields for highbush blueberries vary with the production region.In North America, typical yields for well-managed, mature highbush blue-berry fields were reported as 3 to 4 tons per acre for the northeastern,southern, and southwestern regions, 4 to 4.5 tons per acre for the midwesternregion, and 9 tons per acre for the northwestern region, where yields areconsidered the highest in the world. Yields among fields within a region areextremely variable due to the effects of microclimate, cultivars, and manage-ment practices.1

Fruit for the fresh market may be either packed into its final container inthe field or picked into larger containers (often buckets) and then transportedquickly to a cleaning, sorting, packing, and storage facility. Mechanical colorsorting or hand sorting is done to remove any underripe or damaged fruit.Fruit is quickly cooled using forced air. For longer term storage, berries arekept in a controlled atmosphere. Most berries for the fresh market are nowsold in clamshells and are shipped via refrigerated truck, airplane, or by shipto distant markets. Fruit for processing is transported quickly to a processingplant where it is either individually quick frozen, bulk frozen, pureed, juiced,or freeze-dried, depending on the facility and the end use or market.

1.4.4.2 Lowbush blueberryAlthough there are a few named cultivars of lowbush blueberry, these arenot used to establish new stands, but are available in a few nurseries for the



home garden. Commercial lowbush fields consist mainly of native clones ofV. angustifolium and some V. myrtilloides. Native stands of these species arebrought into commercial production through management practices thatimprove planting density.

The cultural management of lowbush blueberries has changed signifi-cantly in the last 10 years, including increased use of fertilization, irrigation,beehives for pollination, herbicides for weed management, and managementof soil pH, all of which have led to increased yield. Thus total lowbush blue-berry production has increased almost 4-fold over the last 20 years, whilemanaged area has only increased 1.5-fold.5 The use of herbicides allowed theaddition of fertilizer to improve wild blueberry plant growth without stimu-lating weeds and reducing yield. Growers typically use monoammonium ordiammonium phosphate fertilizers to increase yield. The soil pH is monitoredand maintained, preferably below 4.5, to help manage weeds. Currently Maineis the only lowbush blueberry production region that has invested significantlyin irrigation systems, with resulting increases in yield per acre.

There were an estimated 300 to 500 acres of lowbush blueberries pro-duced organically in 2003; this area is expected to increase in the near future.

Only half of the total area of lowbush blueberries is harvested annuallybecause of alternate-year pruning practices.5 Most growers mow the field toabout 1/2 inch above soil level in winter. In the following growing season,straight shoots grow and produce flower buds; these yield the followingyear. Some growers still burn fields to prune in winter, which offers someadvantages for pest control, but has a higher cost than mowing. Averageyields are 1.5 tons per acre, but in a well-managed field yields of 5 tons peracre can be achieved.

Machine harvesting of lowbush blueberries has increased to 40% inMaine and 25% to 80% in Canada, depending on the province. The use ofmachine harvesters is expected to increase in lowbush blueberry productionas well.1 The most common type of machine used is a Bragg (Doug BraggEnterprises, Collingwood, Nova Scotia, Canada) reel-type harvester.5

1.4.5 Cranberry

Commercial cultivation of cranberries began in the 1800s using selectionsfrom the wild. As certain selections gained notoriety, they were given a cultivarname. The most important cultivars grown today are Stevens, Crowley, BenLear, Bergman, and Pilgrim, from breeding programs in the United States,and Early Black, Howes, Searles, and McFarlin, selections from the wild.New cultivars continue to be developed through hybridization, but Stevensis still the most common cultivar planted.

Cranberries are grown in beds or bogs surrounded by perimeter ditchesand dike systems with adjacent water storage areas. In many sites in easternNorth America, stands of native cranberries, growing in peat bogs, havebeen modified to increase yield and facilitate management. However, newplantings have been established on suitable sites. Cranberries are best grown



at a pH of 4.2 to 5.5. In the Pacific Coast region of the United States, cranberrybeds are commonly established on mineral soil, which is naturally acidic,with a semipermeable subsoil and added sand that allows for water floodmanagement of established beds.82

Cranberry farms are divided into a number of beds ranging in size from2 to about 40 acres. Each bed is surrounded by drainage ditches and dikesused as roads. A good source of high-quality water and a reservoir to holdenough water for management of the fields is needed. A permanent sprinklerirrigation system is used to supply water for plant needs as well as for frostprotection in late winter and spring.

Planting is done from January to May, depending on the productionregion. While tissue-cultured, rooted material may be used to establish plant-ings, it is more common to use cuttings or vine material that are spread overthe surface of the planting (up to 2 tons per acre) and then mechanicallypushed into a wet sand layer to a depth of 2 to 4 inches. Planting materialoriginates from prunings of established beds or from beds that are mowedor renovated. Since cranberry beds are established from cuttings of hundreds(if not thousands) of different plants, there is the potential for a lack of geneticuniformity when the bed is planted. Therefore, growers must research theplanting material, its source, its trueness to type (cultivar), and its qualityvery carefully.

The cranberry bed is kept moist to enhance rooting of the cuttings, whichusually occurs in 2 to 4 weeks. The surface of the bed is usually well coveredby runners and plants by the end of the second year. A small yield may beharvested the year after planting, but year 3 is more typically the first pro-duction year, with production increasing until the bed is mature in year 5.

Weed management is critical in cranberries. Weeds compete with theshallow-rooted cranberry plants, may shade vines, and can reduce the effi-ciency of pruning and harvesting equipment.

Water is used in many ways in cranberry production. Sprinkler irrigationis used to satisfy the water requirements of the crop, for frost protection inlate winter and spring, and for evaporative cooling of the vines on hot days.Flooding is used in several ways. In eastern production regions, a winterflood or ice is used to protect plants against cold injury. Flooding for shortperiods of time is used in all production regions as a pest management tool.Finally, many cranberry plantings are harvested using flooding, also called“wet harvesting.”

Berries can be harvested with (wet harvested) or without (dry harvested)the use of flooding. In wet harvesting, the cranberry bed is flooded to justabove the top of the plant canopy. A water reel or “egg beater” machine is driventhrough the flood to agitate the water, forcing berries to pop off the vine. Oncethe beating of a bed is completed, the floating berries are corralled using boomsand are then moved into a truck with a conveyor belt or a berry pump.

Dry harvesting has evolved from the hand scoops used in the early 1900sto several variations of small combine-like machines that are currently beingused. Typically in dry harvesting, the bed is pruned and harvested concurrently.



The Furford picker has horizontal knives to prune mainly runners and tinesor rakes to pick fruit. Prunings and fruit are collected, commonly in burlapbags. Plant material is separated from berries on a mechanical shaker andthe fruit is transported to a storage or packing facility. Dry harvesting is lesscommon than wet harvesting.

Harvesting of mature cranberry fruit occurs from September to November,depending on the cultivar and production region. Growers sometimesreceive a bonus for fruit high in anthocyanin—this is promoted in regionswith cool nights, such as western North America, and with later harvesting.However, in some eastern regions there is added risk of frost damage withlater harvesting. In some areas, cranberries are harvested when they areimmature, before most of the red color develops, for the white cranberryjuice market. Growers are paid a premium to compensate for the lower yieldat this stage of fruit development.

Cranberry yield is still measured in barrels (bbl), the containers used inearly production. One barrel weighs 100 pounds. The average yield rangesfrom 95 to 210 barrels per acre, but yields as high as 700 barrels per acrehave been documented.

Light reaching the uprights and fruit affects flower bud developmentfor next year and fruit color.83 Dense canopies with overgrowth of runnersmay have reduced fruit set if flowers are below runners, reduced harvestefficiency, and less red fruit color.

Vines are typically pruned in winter to remove mainly horizontallygrowing runners, but also to thin uprights. Cranberry pruning machineshave vertical knives, the depth of which can be controlled by the operator.The knives move through the canopy cutting off excess runners and someuprights. Pruning severity can be adjusted by the depth of pruning and thespeed of the machine. Pruning lightly in alternate years has been found toproduce the highest yield and best fruit quality in Oregon.83

Sanding involves the application of a thin (1/2 to 1 inch) layer of sandto an existing cranberry bed to stimulate new rooting of stems closer to thefruiting zone. Sanding can help control weeds, stimulates the production ofnew uprights, and can be used to fill any low areas in the bed and stimulatenew vine growth. Yield may be reduced, however, if too deep a sand layeris applied.84 Many growers sand beds every 3 to 4 years.

Berries in most states are transported directly from the growers’ fieldsto large, centrally located receiving stations operated by handlers. Berriesare cleaned, sorted to remove decayed and damaged fruit, and placed incontainers for storage. Fruit destined for processing is shipped to freezerstorage, where it can be held for months without deterioration. Fruit for thefresh market is air dried (if wet harvested) and stored in ventilated crates atabout 40°F. In Oregon, some fresh market growers are storing fresh fruit “onthe vine” and use delayed harvesting to target later market windows forfresh fruit. The fruit is graded for size (in some markets) and for soundness.Fruit for the fresh market is packed in polyethylene bags or in clamshells.About 94% of the North American cranberry crop in 2004 was processed.




Ribes prefer soil with a pH between 5.5 and 7 and good drainage. Organicmaterials such as sawdust, manure, and bark are usually incorporated intothe soil before planting. Planting distances for gooseberries and currantsrange from 2 to 4 feet in the row, with 10 feet between rows. Black currantsmay be grown at higher densities in hedgerows and cropped in an alternate-year production system. If a pollinizer is required, plantings are establishedwith blocks of 10 rows of each cultivar or with the pollinizer interspersedthroughout the planting. An irrigation system that supplies about 1 inch ofwater per week during the growing season is needed.

There are a large number of cultivars of gooseberry and currant growncommercially. Cultivar performance varies a great deal from one site orgrowing region to another. Various factors need to be considered whenselecting a cultivar, including performance and yield, fruit quality, pest anddisease resistance, growth habit, and suitability for machine harvesting.Barney and Hummer8 provide the characteristics of many cultivars.

Gooseberries are less widely grown commercially than are currants, duemainly to the susceptibility of this crop to powdery mildew (Sphaerothecamors-uvae (Schw.) Berk & Curt and Sphaerotheca macularis (Wallr.:Fr.) Lind.)and the high labor requirement for hand harvesting. Most gooseberries donot machine harvest well, as the spines damage the fruit. In Russia, thecultivars Russkij, Szemena, Kohoznig, and Rekord are grown. Gooseberriespopular in European countries include Weise Triumphbeere, Rote Triumph-beere, Weise Voltragenda, Lady Delamere, Hoennings Fruheste, Triumphant,and Green Giant.48 Gooseberries for processing are generally harvested whenthey are not fully ripe and are very firm and tart. Fully ripe berries are softand sweet, and are used for the fresh market.

Black currants are widely grown in Europe, although damage to flowersfrom spring frosts has resulted in variable yields in some regions. Baldwin,highly susceptible to spring frost, formerly accounted for 80% of the acreagein the United Kingdom,48 but it has been replaced with more cold tolerantcultivars including Ben Lomond and Ben Nevis. Ojebyn is popular in Scan-dinavia and Poland, with Titania and some cultivars from the Scottish CropResearch Institute (SCRI) increasing in popularity. Countries in the formerSoviet Union grow many cultivars, including Golubka, Narjadnaja, Brod-torp, Vystavochnaja, and Stakhanovka Altaja.8 Tenah and Tsema are popularin The Netherlands, and Magnus, Blackdown, and Topsy are being replacedwith cultivars from the SCRI in New Zealand.

The most popular red currant cultivar in northern Europe is Jonkheervan Tets, with yields of 4.5 to 7 tons per acre.8 Other cultivars grown inEurope are Rondom, Rovada, Rosetta, Rotet, Jonifer, Laxton no. 1, Red Lake,Stanza, and Laxton’s Perfection. In Russia, Red Dutch is common.

White currants are mainly grown in Germany and Slovakia and areprimarily processed for baby food. The leading cultivars are Werdavia, Zitavia,Meridian, and Victoria. In Britain, White Versailles is popular, but newercultivars from The Netherlands are replacing some older ones in Europe.8



There is very little commercial production of jostaberry worldwide. Themain cultivars available are Josta, Jostagranda, and Jostaki.

Plantings are typically mature in their third year and last for 10 to 20 years.Mulching with an organic material may be done in some plantings to helpmanage weeds. Annual fertilization with nitrogen at rates of 35 to 90 poundsof nitrogen per acre, depending on the planting age, is typical. Yields ofcurrants and gooseberries range from 2 to 6 tons per acre, depending on thetype and cultivar.


1.4.7.1 LingonberryCommon lingonberry cultivars are Erntedank, Erntekrone, Ida, Koralle,Sanna, Scarlet, and Splendor. Pollinizer cultivars include Red Pearl and Sussi.

Lingonberries are best grown in light, well-drained, acid soil that is highin organic matter. Some plantings are established on raised beds to improvedrainage and organic matter is often incorporated into the soil before plant-ing. Plants are established 8 to 18 inches apart in rows 2 to 3 feet apart. Plantsfill in the rows, as they spread by rhizomes, forming dense matted rows in4 or 5 years. An organic mulch, such as sawdust, is often added to the soilsurface after planting and replenished as needed.

Berries can be once-over harvested when they are light red to dark red.Berries that ripen in summer will senesce if not harvested before the fall crop ismature. Lingonberries are most commonly harvested by hand, using a rakesimilar to that used for lowbush blueberries. Machine harvesting is possible, butis not common at the present time. Yields range from 0.5 to 15 tons per acre.85

Lingonberries can be stored for 3 to 5 weeks under refrigeration. Over-ripe berries do not store well. Worldwide, 10% of the crop is sold for juiceconcentrate.

1.4.7.2 ElderberryThere is limited commercial production of elderberries in the United States,Chile, Canada, Austria, and Italy. Cultivars of S. canadensis include Adams I,Adams II, Johns, York, Nova, and Kent. While there are many ornamentalS. nigra cultivars (e.g., Guincho Purple, Black Lace, Golden), examples ofcultivars grown for fruit include Sampo, Haschberg, and Korsor. Plants willgrow under a wide range of soil conditions, but are most vigorous in fertile,silt loam soils with irrigation. Plant spacing ranges from 5 to 7 feet in therow, with 10 to 13 feet between rows. Very little, if any fertilizer is recom-mended, particularly in the planting year. Pruning involves removing canesthat are more than 3 years old, leaving a total of 7 to 9 canes per plant. Fullproduction of up to 15 pounds of fruit per plant usually occurs in the thirdor fourth year. In mature, vigorous plantings, yields of up to 6 tons per acre arepossible.

Fruit mature from mid-August to mid-September, depending on thecultivar and growing region. Clusters ripen over a period of 5 to 15 days.



Entire fruit clusters are harvested by clipping the peduncle for later strippingof individual berries and immediate processing or freezing. Clusters may befrozen, with the berries knocked off later.

1.4.7.3 Hardy kiwifruitActinidia arguta is a vigorous perennial vine that must be trained to a supportstructure. The most common trellis used worldwide is the pergola; however,many growers feel that Ananasnaya is more easily pruned when trained toa “T-bar” system.49 In heavily shaded canopies, growers have observed pre-mature fruit softening with a relatively low percent soluble solids, makingthe fruit unmarketable—this problem is much reduced when canopies arewell pruned to improve the fruit’s light exposure. Vines are trained to a 6 footor higher trunk so workers can walk under the plant canopy for harvestingand pruning.

Plants are most commonly established at a spacing of 15 feet × 15 feet,equal to 194 total plants and 172 female plants per acre. Plants are dioecious,meaning they are either male or female, so the flowers of the female Anan-asnaya must be cross-pollinated with male selections of A. arguta planted aspollinizers, with a planting ratio of one male vine for every 6 to 10 femalevines. Honeybees are the predominant pollinators with 4 to 5 hives recom-mended per acre.

Kiwifruit vines grow best on deep, well-drained soil with a pH between5.5 and 6.0. Commercial growers often plant in raised beds to help avoidproblems with phytophthora root rot (Phytophthora cryptogea Pethybr. & Laf-ferty). Young kiwifruit shoots are very sensitive to frost and wind injury.Growers install irrigation for frost protection to protect plants after bud breakand install windbreaks to reduce wind damage to shoots and fruit. Kiwifruitvineyards need frequent irrigation during the growing season, so a supplyof good quality irrigation water is required for production.

Kiwifruit vineyards must be pruned annually for consistent productionof quality fruit. About 70% of the wood that grew the previous season isremoved. Vines are normally pruned to a bilateral cordon with about twenty2-foot long spurs in the “T-bar.” Female vines are pruned in the dormantseason, whereas male vines are shaped in the dormant season and mostpruning occurring after bloom in early summer.49

Commercially, fruit are generally once-over harvested by hand at anaverage 8 to 10 °Brix, which typically occurs in September. At harvest, mostfruit is still green and firm, although a small percentage (generally less than4% of the total yield) are very soft and unusable.86 Fruit cannot be harvestedvine ripe, as it is then too soft to handle or store. Vine-ripened fruit continueto increase in °Brix to 21% to 23%, depending on the cultivar.87

After harvesting, the fruit is immediately cooled to 33°F to 35°F andsorted, with culls (usually scarred or small fruit) removed and the remainingmarketable fruit sorted by size. Packing varies by shipper, but typicallyclamshells are used. Low-vent packages reduce desiccation of the fruit com-pared to the traditional vented clamshells used for berry fruit. Fruit harvested



at 9 °Brix and treated with an edible coating (SemperFresh) had reducedweight loss and a more favorable appearance or glossiness to the fruit.88 Thefruit remain in cold storage, under relatively high humidity, with ethylenegases scrubbed to retard ripening. The fruit can be stored for 4 to 8 weeks,depending on the storage conditions (temperature, ethylene and oxygenlevels, and humidity).

Variable fruit quality (fruit size, °Brix, firmness, and subsequent flavor),relatively short storage life compared to A. deliciosa Hayward, short harvestseason, and desiccation during shipping and in stores are the major problemsrelated to fresh marketing hardy kiwifruit. Variability in fruit size can bereduced with good pruning and ensuring good pollination.

Total yields of Ananasnaya in Oregon range from 30 to 100 pounds pervine in 4- to 5-year-old commercial vineyards. Vines are not consideredmature until year 7 or 8. Total yields of mature Ananasnaya range from 66to 160 pounds per vine (6 to 14 tons per acre).87 Yield and fruit size are verymuch affected by pruning severity.

References1. Strik, B. and Yarborough, D., Blueberry production trends in North America,

1992 to 2003 and predictions for growth, HortTechnology, 15, 391, 2005.2. Strik, B.C., Clark, J.R., Finn, C., and Banados, M.P., Worldwide production of

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Rocky Mountains, Fruit Var. J., 46, 217, 1992.4. Clark, J.R., Changing times for eastern United States blackberries, HortTech-

nology, 15, 491, 2005.5. Yarborough, D.E., Factors contributing to the increase in productivity in the

wild blueberry industry, Small Fruits Rev., 3, 33, 2004.6. Strik, B.C., Blueberry—an expanding world berry crop, Chron. Hort., 45, 7, 2005.7. Brennan, R.M., Currants and gooseberries, in Fruit Breeding, Vol. 2, Vine and

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8. Barney, D.L. and Hummer, K.E., Currants, Gooseberries, and Jostaberries. AGuide for Growers, Marketers, and Researchers in North America, Haworth Press,Binghamton, NY, 2005.

9. Williams, M.H., Boyd, L.M., McNeilage, M.A., MacRae, E.A., Ferguson, A.R.,Beatson, R.A., and Martin, P.J., Development and commercialization of “babykiwi” (Actinidia arguta Planch.), Acta Hort. (ISHS), 610, 81, 2003.

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15. Eck, P., Blueberry Science, Rutgers University Press, New Brunswick, NJ, 1988.16. Eck, P., The American Cranberry, Rutgers University Press, New Brunswick,

NJ, 1990.17. Ellis, M.A., Converse, R.H., Williams, R.N., and Williamson, B., Eds., Com-

pendium of Raspberry and Blackberry Diseases and Insects, American Phytopatho-logical Society Press, St. Paul, MN, 1991.

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19. Darrow, G.M., The Strawberry, Holt, Rinehart and Winston, New York, 1966.20. Dana, M.N., The strawberry plant and its environment, in The Strawberry:

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21. Hancock, J.F., Strawberries, CABI Publishing, New York, 1999.22. Strik, B.C. and Proctor, J.T.A., The relationship between achene number,

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23. Jennings, D.L. Raspberries and Blackberries: Their Breeding, Diseases and Growth,Academic Press, San Diego, 1988.

24. DeGomez, T.E., Martin, L.W., and Breen, P.J., Effect of nitrogen and pruningon primocane fruiting red raspberry ‘Amity,’ HortScience, 21, 441, 1986.

25. Lockshin, L.S. and Elfving, D.C., Flowering response of ‘Heritage’ red rasp-berry to temperature and nitrogen, HortScience, 16, 527, 1981.

26. Carew, J.G., Gillespie, T., White, J., Wainwright, H., Brennan, R., and Battey,N.H., The control of the annual growth cycle in raspberry. J. Hort. Sci.Biotechnol., 75, 495, 2000.

27. Strik, B.C., Blackberry cultivars and production trends in the Pacific North-west, Fruit Var. J., 46, 202, 1992.

28. Takeda, F., Strik, B.C., Peacock, D., and Clark, J.R., Cultivar differences andthe effect of winter temperature on flower bud development in blackberry, J.Am. Soc. Hort. Sci., 127, 495, 2002.

29. Takeda, F., Strik, B.C., Peacock, D., and Clark, J.R., Patterns of floral buddevelopment in canes of erect and trailing blackberry, J. Am. Soc. Hort. Sci.,128, 3, 2002.

30. Strik, B.C, et al., Caneberry research at North Willamette Research and Ex-tension Center—an update, Proc. Oregon Hort. Soc., 141, 1994.

31. Warmund, M.R. and Byers, P.L., Rest completion in seven blackberry (Rubussp.) cultivars, Acta Hort. (ISHS) 585, 693, 2002.

32. Crandall, P.C., Bramble Production. The Management and Marketing of Raspberriesand Blackberries, Food Products Press, Binghamton, NY, 1995.

33. Warmund, M.R. and George, M.F., Freezing survival and super-cooling inprimary and secondary buds of Rubus spp., Can. J. Plant Sci., 70, 893, 1990.

34. Camp, W.H., The North American blueberries with notes on other groups ofVacciniaceae, Brittonia, 5, 203, 1945.

35. Eck, P., Botany, in Blueberry Culture, Eck, P. and Childers, N., Eds., RutgersUniversity Press, New Brunswick, NJ, 1966, p. 14.

36. Aalders, L.E. and Hall, I.V., A comparison of flower bud development in thelowbush blueberry, V. angustifolium Ait. under greenhouse and filed condi-tions, Proc. Am. Soc. Hort. Sci., 85, 281, 1964.



37. Gough, R.E., Shutak, V.G., and Hauke, R.L., Growth and development ofhighbush blueberry. II. Reproductive growth, histological studies, J. Am. Soc.Hort. Sci., 103, 476, 1978.

38. Huang, Y.H., Johnson, C.E., and Sundberg, M.D., Floral morphology anddevelopment of ‘Sharpblue’ southern highbush blueberry in Louisiana, J. Am.Soc. Hort. Sci., 122, 630, 1997.

39. Ritzinger, R. and Lyrene, P.M., Flower morphology in blueberry species andhybrids, HortScience, 34, 130, 1999.

40. Darnell, R.L. and Lyrene, P.M., Cross-incompatibility of two related rabbiteyeblueberry cultivars, HortScience, 24, 1017, 1989.

41. Davies, F.S., Flower position, growth regulators, and fruit set of rabbiteyeblueberries, J. Am. Soc. Hort. Sci., 111, 338, 1986.

42. Morrow, E.B., Some effects of cross-pollination versus self-pollination in thecultivated blueberry, Proc. Am. Soc. Hort. Sci., 42, 469, 1943.

43. Eck, P., Blueberry, in Handbook of Fruit Set and Development, Monselise, S.P.,Ed., CRC Press, Boca Raton, FL, 1986, p. 75.

44. Maust, B.E., Williamson, J.G., and Darnell, R.L., Flower bud density affectsvegetative and fruit development in field-grown southern highbush blueberry,HortScience, 34, 607, 1999.

45. Forsyth, F.R. and Hall, I.V., Ethylene production with accompanying respira-tion rates from the time of blossoming to fruit maturity in three Vacciniumspecies, Nat. Can., 96, 257, 1969.

46. Birkhold, K.T., Koch, K.E., and Darnell, R.L., Carbon and nitrogen economyof developing rabbiteye blueberry fruit, J. Am. Soc. Hort. Sci., 117, 139, 1992.

47. Dana, M.N., Cranberry management, in Small Fruit Crop Management, Galletta,G.J. and Himelrick, D., Eds., Prentice Hall, Englewood Cliffs, NJ, 1990, p. 334.

48. Harmat, L., Porpaczy, A., Himelrick, D.G., and Galletta, G.J., Currant andgooseberry management, in Small Fruit Crop Management, Galletta, G.J. andHimelrick, D.G., Eds., Prentice Hall, Englewood Cliffs, NJ, 1990, p. 245.

49. Strik, B.C., Growing Kiwifruit, Extension Service Publication PNW 507, OregonState University, Corvallis, OR, 2005.

50. Tiyayon, C. and Strik, B.C., The influence of time of overhead shading onyield, fruit quality, and subsequent flowering of hardy kiwifruit, Actinidiaarguta, N. Z. J. Crop Hort. Sci., 32, 235, 2004.

51. Kabaluk, J.T., Kempler, C., and Toivonen, P.M.A, Actinidia arguta—characteristicsrelevant to commercial production, Fruit Var. J., 51, 117, 1997.

52. Galletta, G.J. and Himelrick, D.G., Eds., Small Fruit Crop Management, PrenticeHall, Englewood Cliffs, NJ, 1990.

53. Childers, N.F. and Lyrene, P.M., Eds., Blueberries. For Growers, Gardeners,Promoters, Dr. Norman F. Childers Publications, Gainesville, FL, 2006.

54. Gough, R.E., The Highbush Blueberry, Food Products Press, Binghamton, NY,1994.

55. Childers, N.F., Ed., Strawberries. A Book for Growers, Others, Dr. Norman F.Childers Publications, Gainesville, FL, 2003.

56. Davenport, J., DeMoranville, C., Hart, J., Poole, R., Roper, T., Planer, T., Larson,B., and Pozdnyakova, L., Nitrogen for Bearing Cranberries, Hart, J., Ed., Exten-sion Service Publication EM 8741, Oregon State University, Corvallis, OR,2000, p. 17.

57. Hart, J., Strik, B.C., and Rempel, H., Caneberries. Nutrient Management Guide,Extension Service Publication EM 8903-E, Oregon State University, Corvallis,OR, 2006.



58. Hart, J., Strik, B.C., Yang, W., and White, L., Nutrient Management Guide forBlueberries in Oregon, Extension Service Publication EM 8918, Oregon StateUniversity, Corvallis, OR, 2006.

59. Pritts, M. and Handley, D., Eds., Bramble Production Guide, NRAES 35, NaturalResource, Agriculture, and Engineering Service, Ithaca, NY, 1989.

60. Lieten, P., Strawberry production in central Europe, Int. J. Fruit Sci., 5, 91, 2005.61. Strik, B. and Cahn, H., Pruning and training affect yield but not machine

harvest efficiency of ‘Meeker’ red raspberry, HortScience, 34, 611, 1999.62. Strik, B.C., A review of nitrogen nutrition of Rubus, Acta Hort., 2007 (in press).63. Rempel, H., Strik, B.C., and Righetti, T., Uptake, partitioning and storage of

fertilizer nitrogen in red raspberry as affected by rate and timing of applica-tion, J. Am. Soc. Hort. Sci., 129, 439, 2004.

64. Papp, J., Kobzos-Pápai, I., and Nagy, J., Effect of nitrogen application on yield,leaf nutrient status and fruit chemical composition of raspberry and redcur-rant varieties, Acta Agron. Acad. Sci. Hung., 33, 337, 1984.

65. Nelson, E. and Martin, L.W., The relationship of soil-applied N and K to yieldand quality of ‘Thornless Evergreen’ blackberry, HortScience, 21, 1153, 1986.

66. Alleyne, V. and Clark, J.R., Fruit composition of ‘Arapaho’ blackberry followingnitrogen fertilization, HortScience, 32, 282, 1997.

67. Malik, H., Archbold, D., and MacKown, C.T., Nitrogen partitioning by ‘Ches-ter Thornless’ blackberry in pot culture, HortScience, 26, 1492, 1991.

68. Mohadjer, P., Strik, B.C., Zebarth, B.J., and Righetti, T.L., Nitrogen uptake,partitioning and remobilization in ‘Kotata’ blackberry in alternate-yearproduction, J. Hort. Sci. Biotechnol., 76, 700, 2001.

69. Strik, B.C., Clark, J.R., Finn, C., and Buller, G., Management of primocane-fruiting blackberry to maximize yield and extend the fruiting season, ActaHort., 2007 (in press).

70. Eleveld, B., Strik, Brown, K., and Lisec, B., Marion Blackberry Economics. TheCosts of Establishing and Producing ‘Marion’ Blackberries in the Willamette Valley,Extension Service Publication EM 8773, Oregon State University, Corvallis,OR, 2001.

71. Bell, N., Strik, B.C., and Martin, L.W., Effect of date of primocane suppressionon ‘Marion’ trailing blackberry. II. Cold hardiness, J. Am. Soc. Hort. Sci., 120,25, 1995.

72. Cortell, J. and Strik, B.C., Effect of floricane number in ‘Marion’ trailingblackberry. I. Primocane growth and cold hardiness, J. Am. Soc. Hort. Sci., 122,604, 1997.

73. Strik, B. and Buller, G., Reducing thorn contamination in machine-harvested‘Marion’ blackberry, Acta Hort., 585, 677, 2002.

74. Strik, B. and Buller, G., Improving yield and machine harvest efficiency of‘Bluecrop’ through high-density planting and trellising, Acta Hort., 574, 227,2002.

75. Strik, B. and Buller, G., The impact of early cropping on subsequent growthand yield of highbush blueberry in the establishment years at two plantingdensities is cultivar dependant, HortScience, 40, 1998, 2005.

76. Bryla, D.R. and Strik, B.C., Variation in plant and soil water relations amongirrigated blueberry cultivars planted at two distinct in-row spacings, ActaHort., 715, 295, 2006.

77. Eleveld, B., Strik, B., DeVries, K., and Yang, W., Blueberry Economics. The Costsof Establishing and Producing Blueberries in the Willamette Valley, Extension ServicePublication EM 8526, Oregon State University, Corvallis, OR, 2005.



78. Strik, B., Buller, G., and Hellman, E., Pruning severity affects yield, berryweight, and picking efficiency of highbush blueberry, HortScience, 38, 196,2003.

79. Aalders, L.E., Hall, I.V., and Forsyth, F.R., Effects of partial defoliation andlight intensity on fruit set and berry development in the lowbush blueberry,Hort. Res., 9, 124, 1969.

80. Patten, K. and Neuendorff, E., Influence of light and other parameters on thedevelopment and quality of rabbiteye blueberry fruit, in Proceedings of theTexas Blueberry Growers Association Convention, Texas Blueberry GrowersAssociation, Georgetown, TX, 1989, p. 109.

81. Strik, B.C., Brazelton, D., Penhallegon, R., and Ketchum, L., A Grower’s Guideto Pruning Highbush Blueberries, DVD 2, Oregon State University, Corvallis,OR, 1990.

82. Strik, B.C., Bristow, P., Broaddus, A., Davenport, J., Defrancesco, J.T., English,M., Fisher, G., Fitzpatrick, S., Hart, J., Henderson, D., Larson, B., Patten,K., Pinkerton, J., Poole, A., Pscheidt, J., and Vorsa, N., Cranberry Production inthe Pacific Northwest, Extension Service Publication PNW 247, Oregon StateUniversity, Corvallis, OR, 2002.

83. Strik, B.C. and Poole, A.P., Alternate year pruning recommended for cranberry,HortScience, 27, 1327, 1992.

84. Strik, B.C. and Poole, A., Does sand application to soil surface benefitcranberry production? HortScience, 30, 47, 1995.

85. Penhallegon, R., Lingonberry Production Guide for the Pacific Northwest,Extension Service Publication PNW 583-E, Oregon State University, Corvallis,OR, 2006.

86. Tiyayon, C. and Strik, B.C., Flowering and fruiting morphology of hardykiwifruit, Actinidia arguta, Acta Hort., 610, 171, 2003.

87. Strik, B. and Hummer, K., ‘Ananasnaya’ hardy kiwifruit, J. Am. Pomol. Soc.,60, 106, 2006.

88. Fisk, C.L., McDaniel, M.R., Strik, B.C., and Zhao, Y., Physicochemical, sensory,and nutritive qualities of hardy kiwifruit (Actinidia arguta ‘Ananasnaya’) asaffected by harvest maturity and storage, J. Food Sci., 74, 210, 2006.



51

chapter 2

Chemical componentsof berry fruits

Stephen T. Talcott

Contents

2.1 Introduction ................................................................................................. 512.2 Basic chemical compositions of berries................................................... 54

2.2.1 Carbohydrates................................................................................. 542.2.2 Organic acids .................................................................................. 552.2.3 Enzymes........................................................................................... 552.2.4 Cell wall components .................................................................... 562.2.5 Berry pigments ............................................................................... 572.2.6 Vitamins and minerals .................................................................. 58

2.3 Chemical content of berries ...................................................................... 582.3.1 Strawberry ....................................................................................... 632.3.2 Blueberry ......................................................................................... 662.3.3 Blackberry........................................................................................ 662.3.4 Raspberry......................................................................................... 67

2.4 Conclusion.................................................................................................... 67References.............................................................................................................. 68

2.1 Introduction

Berries are universally recognized as having a basic chemical compositionthat accentuates their sweet taste, fruity aroma, and healthy properties thatare enjoyed by societies throughout the world. Berries are soft fruits thatrange in color from red to blue or black. They a good source of essentialvitamins and minerals, and have diverse phytochemical compositions thatrelate to consumer satisfaction and health. The chemical composition of berryfruits can be highly variable depending on the cultivar, growing location,

5802_C002.fm Page 51 Thursday, March 22, 2007 10:17 AM


ripeness stage, and harvest and storage conditions because of their generallynonclimacteric nature with respect to their production and response toethylene. In addition, the environmental conditions of growth can be a majorfactor impacting overall fruit quality. Although numerous chemical param-eters relate to berry quality, identifying specific quality factors beyond simplesugar content is difficult because there are numerous factors that relate toconsumer acceptance. However, the overall quality of many berry types isattributable to harvesting at the maximal level of ripeness when fruits havetheir highest sugar and aroma content. Other factors include a proper sugar/acid balance, firm texture, volatile aroma profile, and external color derivedfrom anthocyanins, which generally relate to consumers’ perception of quality.Once consumed, the nutritional benefits of berries are realized from their car-bohydrate, vitamin, mineral, dietary fiber, and polyphenolic concentrations.Different varieties of berries contain highly variable concentrations of ascorbicacid, folic acid, select minerals, carotenoids, and a diversity of polyphenolicsthat impact color, taste, and nutrition. Berries are generally low in calories andhigh in dietary fiber and contain only small amounts of fat and protein(Table 2.1). Fruit and vegetable consumption has been widely associated withdecreased incidences of chronic diseases, including coronary heart disease andcancer. With national trends to increase fruit, vegetable, and whole grain con-sumption, berries provide an important source of chemical compounds essen-tial for human health.

1

Understanding those factors that influence consumer perception ofberry quality is important for the selection of new or improved breedinglines and in developing new food formulations with berries or berry fla-vors. Those quality factors within the control of producers include harvest-ing at optimal ripeness, proper temperature control, and variations instorage environment, such as controlled/modified atmospheres and rela-tive humidity. These conditions can influence numerous biochemicalchanges that affect overall fruit quality.

2,3

The degree of fruit ripeness notonly impacts the color and flavor, but also the postharvest keeping quality.Some changes in berries during maturation and ripening are evident, suchas the loss of chlorophyll, the development of secondary metabolites thatinfluence color, and the production of aroma volatiles. However, moresubtle changes also occur during fruit development and postharvest han-dling, such as changes in the balance of sugars and acids and altered cellwall chemistry, which influence consumer perception of texture and juici-ness. As the fruit reach the point of marketability, careful consideration ofharvesting and handling conditions is critical for fruit quality. Initialremoval of field heat and storage in a high relative humidity environmentwill prevent excessive moisture loss, slow microbial decay, and decreasethe activity of cell wall active enzymes that cause rapid deterioration.Despite the many beneficial properties of berries based on their concentra-tions of vitamins, minerals, fiber, and antioxidant polyphenolics, if thequality of the fruit is below consumer acceptance for purchase, such ben-efits are never realized.


Chapter 2: Chemical components of berry fruits 53

Tabl

e 2.

1

Che

mic

al C

onte

nt o

f Pr

oxim

ates

and

Car

bohy

dra

tes

in B

erri

es F

rom

the

U.S

. Dep

artm

ent

of A

gric

ultu

re N

utri

ent

Dat

abas

e

2

Blu

eber

ryB

lack

berr

yR

asp

berr

yB

oyse

nbe

rry

Stra

wbe

rry

Bla

ck c

urr

ant

Goo

sebe

rry

Red

cu

rran

tH

uck

lebe

rry

Eld

erbe

rry

Wat

er (

g)84

.288

.285

.885

.990

.95

81.9

687

.87

83.9

590

.779

.8E

nerg

y (k

cal)

5743

5250

3263

4456

3773

Prot

ein

(g)

0.74

1.39

1.2

1.1

0.67

1.4

0.88

1.4

0.4

0.66

Tota

l lip

ids

(g)

0.33

0.49

0.65

0.26

0.3

0.41

0.58

0.2

0.1

0.5

Ash

(g)

0.24

0.37

0.46

0.54

0.4

0.86

0.49

0.66

0.1

0.64

Car

bohy

dra

te

a

(g)

14.5

9.61

11.9

12.2

7.68

15.3

810

.18

13.8

8.7

18.4

Tota

l fibe

r (g

)2.

45.

36.

55.

32.

0N

A4.

34.

3N

A7

Tota

l sug

ars

(g)

9.96

4.88

4.42

6.89

4.66

NA

NA

7.37

NA

NA

Sucr

ose

(g)

0.11

0.07

0.2

NA

0.12

NA

NA

0.61

NA

NA

Glu

cose

(g)

4.88

2.31

1.86

NA

2.04

NA

NA

3.22

NA

NA

Fruc

tose

(g)

4.97

2.4

2.35

NA

2.5

NA

NA

3.53

NA

NA

Mal

tose

(g)

ND

0.07

ND

NA

ND

NA

NA

NA

NA

NA

Gal

acto

se (

g)N

D0.

03N

DN

AN

DN

AN

AN

AN

AN

ASt

arch

(g)

0.03

ND

ND

NA

0.04

NA

NA

NA

NA

NA

a

Car

bohy

dra

te c

alcu

late

d b

y d

iffe

renc

e fr

om p

roxi

mat

e an

alys

is.

NA

, not

ava

ilabl

e; N

D, n

ot d

etec

ted

.



2.2 Basic chemical compositions of berries

2.2.1 Carbohydrates

The chemical properties affecting berry flavor are a combination of volatileand nonvolatile compounds that relate to the basic taste, color, texture, andaroma of the fruit. Paramount to overall flavor is the composition and con-centration of soluble sugars (sucrose, glucose, and fructose) in relation toorganic acids and aroma volatiles (Table 2.1). Fruit harvest must be delayeduntil the fruit is ripe enough to accumulate sufficient sugars to balance fruitacidity and astringency. Therefore, the timing of the harvest and subsequentpostharvest handling conditions are critical because of the relatively shortshelf life from harvest to retail distribution. Varying sugar contents in relationto the overall flavor are common factors that relate to cultivar differentiationof strawberries,

4

yet sugar content alone is generally a poor index for thetable quality of berry fruits.

The sugar content of ripe berries is generally an equimolar mixture ofglucose and fructose, with sucrose concentrations varying based on thedegree of ripeness or duration of postharvest storage. In berry plants, thecarbon from photosynthesis is most often directed into sucrose for transportvia the phloem into starch and other molecules, but starch is not significantlyaccumulated in berry fruits.

4

Although starch is the primary storage reservein plants and is formed into starch granules via starch synthesis that poly-merizes adenosine diphosphate (ADP)-glucose into higher molecular weightpolymers, its storage in berry plants is primarily in the roots, stems, andleaves and it is only present in the early stages of fruit development.

5

As amixture of two-glycan polymers (amylase and amylopectin), starch is criticalfor plant growth and development as a reserve energy source. During earlyberry development, sucrose generally dominates as the primary carbohy-drate and is converted to glucose and fructose as ripening progresses, andits conversion and formation can continue during postharvest storage.Sucrose is a nonreducing disaccharide composed of

α

-D-glucopyranosideand

β

-D-fructofuranoside and is not a respiratory substrate since it cannotbe phosphorylated. Sucrose hydrolysis can occur via an acid-catalyzed reac-tion, but hydrolysis from invertase activity in berry fruit during maturationand ripening is more likely to yield high concentrations of glucose andfructose in the ripe fruit. Since fructose is characteristically sweeter thanglucose or sucrose, its concentration in berries is a desirable organoleptictrait, but total sugar content is generally a better marker for consumer accept-ability. Among the factors affecting fruit quality, concentrations of solublesugars are most commonly measured in relation to the organoleptic factorsof sweetness, acidity, astringency, and overall flavor perception. For freshfruits, the majority of consumers prefer sweeter fruit; this is not only aconsequence of higher sugar concentration, but also the balance among acids,aroma active volatiles, and other constituents, such as polyphenolics, thatcan affect sweetness perception.



2.2.2 Organic acids

The sugar content in berries is counterbalanced by the presence of severalpredominant organic acids such as citric and malic acid, as well as phenolicacids that can impart bitter or astringent flavors, that are responsible for thebasic taste components. The compliment of organic and phenolic acids inberries is responsible for the titratable acidity of the fruit and is commonlymeasured as an overall index of fruit quality, whereas measurements of pHare often poor indicators of fruit quality characteristics. High concentrationsof organic acids in most fruits is also critical for fruit preservation, maintain-ing a low pH in processed fruit applications such as jams and jellies.

6,7

Organic acids also help to stabilize ascorbic acid and are critical in fruit colorby serving to stabilize anthocyanins and extend the shelf life of fresh andprocessed berries.

2.2.3 Enzymes

The presence of various hydrolase and oxidase enzymes in fresh, damaged,and pureed berries can cause significant quality deterioration, including aloss of color and texture, and the formation of undesirable brown pigments.The presence of oxidizing enzymes has been reported in a variety of berriesand is detrimental to color, nutritional components, and overall acceptability.The extent of browning from enzymes such as polyphenol oxidase (PPO; EC1.14.18.1) or peroxidase (POD; EC 1.11.1.7) is often initially masked by thedark red color of the anthocyanins, but eventually secondary oxidation orcondensation reactions occur that alter consumer appeal. The activity of PPO(or POD when hydrogen peroxide is present) catalyzes the oxidation of

o

-diphenolic compounds, which will eventually polymerize into brown pig-ments. POD was found to increase with fruit development in blueberries

8

and was found ionically bound to the cell wall. The type and amount ofoxidase enzymes greatly influences overall fruit quality and may be limitedby either enzyme or substrate concentrations, yet berries have an abundanceof polyphenolic substrates such as phenolic acids and flavan-3-ols. Tech-niques to reduce the harmful effects of enzymes include proper refrigeration,reduced oxygen, pH modification, the addition of enzyme inhibitors, or theaddition of reducing agents to control secondary oxidation products. Inmany varieties of berries, PPO and POD are the primary enzymes respon-sible for destruction of phytochemicals and quality characteristics

8–10

andtheir activity is related to fruit ripeness, physical damage, and storage tem-perature.

Cell wall degrading enzymes are also important components affectingoverall fruit quality as they relate to ripening and postharvest shelf life. Sinceberries do not have a protective pericarp and possess only a thin cuticle layer,they are particularly susceptible to wounding and the action of enzymes.Because of the high content of pectic substances in most berries, the actionof polygalactouronase (PG; EC 3.2.1.15) to cleave pectin chains is a major



factor influencing fruit texture. Pectin modification is further aided by theaction of pectin methyl esterase (PME; EC 3.1.1.11), which is a ubiquitousenzyme that serves to cleave methyl esters from methoxylated pectins forsubsequent depolymerization by PG. Other components of the cell wallinclude cellulose and hemicellulose, which are also depolymerized by theaction of various glucanases. An endo-1,4-

β

-D-glucanase (EC 3.2.1.4) wasfound to act primarily on hemicellulose in strawberries, contributing to theirsoftening during storage.

11

The degradation of hemicellulose is often moni-tored by the loss of five-carbon neutral sugars from the activity of carbohy-drate-specific enzymes such as

β

-galactosidase.

2.2.4 Cell wall components

Fruit softening and enzymatic changes affecting berry texture are importantcomponents of fruit quality that are often overlooked as parameters affectingconsumer perception. A balance exists from fruit development and ripeningto harvest such that the fruit is firm enough for handling but not overly softas to adversely impact the perception of quality. Berry harvesting is often ahighly subjective determination, where underripe fruit is texturally too hardand has consumer appeal, yet excessively soft fruit damages easily andcontributes to a loss in farm value. However, quality deterioration of ripeberries is often related to excessive fruit softening and the appearance ofmold or bacterial decay. Changes in cell wall solubilization, primarily frompectin degradation of the middle lamella, is the primary means by whichberries soften. As berries mature and ripen, major textural changes occur asa result of ripening, overripening, fruit damage, or the action of cell walldegrading enzymes during storage. The adequacy of ripeness based ontexture, along with color and flavor, must be subjectively made at the timeof harvest.

Postharvest changes associated with berry ripening proceed at variablerates and in a manner dependent on storage temperature, microbial load,fruit damage, and composition of the cell wall.

12

Changes in berry textureare the result of degradation of cell wall constituents including pectin, cel-lulose, hemicellulose, glycoproteins, and esterified polyphenolics as compo-nents of dietary fiber

13

and are important components affecting fruit qualityas they relate to ripening and postharvest shelf life. These compounds arecontinually changing throughout fruit development, ripening, and posthar-vest storage.

14–16

Enzymatic action results in polysaccharide depolymeriza-tion and subsequent conversion of high molecular weight, water insolublepolymers to increasingly water soluble components that result in fruit soft-ening, enhanced susceptibility to microbial infection, surface browning, andeventually a decrease in consumer acceptability.

Berry cell walls contain a high concentration of pectic substances thatare cleaved by the action of PG, influencing fruit texture. The normal pro-gression of fruit ripening leads to an increase in water soluble pectins anda subsequent decrease in higher molecular weight pectic substances. Perkins



et al.

17

observed blackberry softening during maturation and ripening by theformation of water soluble uronic acids that increased as much as 50% aspectin solubility increased. Other cell wall components include cellulose andhemicellulose, which are also depolymerized by the action of various glu-canases. Polysaccharide degradation can occur from the activation of cellwall bound enzymes or derived from fungal pathogens, altering fruit tex-ture.

15

However, polysaccharide depolymerization reactions are not alwaysdetrimental to quality, since fruit softening is critical during fruit ripeningand for consumer perception of quality. As dietary fiber, levels of both solubleand insoluble polysaccharides have been suggested to enhance humanhealth by reducing serum cholesterol, low-density lipoprotein (LDL) choles-terol, and the risk of coronary heart disease, enhancing satiety, and slowingthe uptake of sugars from the diet, influencing diabetic responses.

18

2.2.5 Berry pigments

One of the most distinguishing features of most berries is their deep red,blue, or purple color derived from anthocyanins, which is the subject ofChapters 3, 4, and 5. Visual perception of fresh and processed fruit color isthe first factor influencing quality perception, superseding both flavor andtextural perceptions. Berry color can be influenced by ripeness at harvestingand by numerous degradative reactions to anthocyanins in fresh and pro-cessed products, including microbial load, enzymatic action, pH, the pres-ence of ascorbic acid, and the extent of thermal processing.

Other compounds with the potential to contribute to the color of fruitare common carotenoids, such as lutein and

β

-carotene, which have beenreported in concentrations up to 46

µ

g/g of dry fruit weight in blueberries,black currants, black chokeberries, lingonberries, and raspberries.

19

Although these concentrations are low in relation to other carotenoid-richfruits and vegetables, their presence indicates the phytochemical diversityamong the berry fruits, along with the antioxidant vitamins and polyphe-nolics that contribute to the health benefits of berry fruits.

Differences among cultivars, the degree of ripeness, postharvest han-dling, and the degree of processing are major factors influencing the color ofberry fruits. In fresh fruit, color losses can be attributed to oxidative andenzyme-catalyzed reactions. Once fruit is damaged or processed to inducecellular decompartmentalization, free radical-induced or enzyme-catalyzedoxidation reactions contribute to overall color loss in the fruit. Although mostoxidase enzymes are unable to act directly on anthocyanins, the formationof

o

-quinones by PPO and the breakdown of peroxides by POD can inducesecondary oxidative reactions or form condensation products that are detri-mental to color stability.

20

Berries contain a diversity of nonanthocyaninpolyphenolics that are substrates for oxidation, including hydroxycinnamicacids and flavan-3-ols that serve as the basis for anthocyanin degradationupon their oxidation. Studies have shown that anthocyanins with an

o

-diphenolic substitution are more affected by these oxidation and condensation



reactions.

20,21

The presence of ascorbic acid in berries can also affect colorstability in both beneficial and detrimental mechanisms.

22–24

As a reducingagent, ascorbic acid can augment the effects of

o

-quinones before they reactwith anthocyanins,

25

but during long-term storage ascorbic acid can exacer-bate anthocyanin color stability in a mutually destructive reaction mecha-nism.

23,26,27

In addition, metal-catalyzed destruction of color components inthe presence of ascorbic acid or residual peroxide has long been a recognizedmechanism for the destruction of plant pigments.

28

2.2.6 Vitamins and minerals

Berries contain a diverse array of nutrients with recognized biological activ-ities that promote or contribute to health. The content and diversity of vita-mins (Table 2.2), minerals (Table 2.3), and dietary fiber are often the basis forpromoting increased daily intake of fruits and vegetables. Many berries con-tain large concentrations of food folate, B vitamins such as niacin, tocopherols,and vitamin K, which are important for human health. Major minerals inberries include potassium, phosphorous, calcium, and magnesium. Manyberries are known for their high ascorbic acid content, which varies amongberry varieties and among genotypes, as well as their diversity of polyphe-nolics, which are the major contributors to total antioxidant capacity. Someberry cultivars have enough ascorbic acid to provide 100% of the daily valuein a single serving. One of the most important roles of ascorbic acid is itsability to act as a reducing agent, augmenting the effects of oxidase enzymesby reducing

o

-quinones back to their

o

-diphenolic configuration. Ascorbicacid has many recognized health benefits, including collagen and hormonesynthesis, antiscorbutic activity, and a wide range of benefits relating toenhanced immunity.

1,29

The stability of ascorbic acid is known to be influ-enced by numerous factors, including temperature, light exposure, atmo-sphere, fruit damage, food processing, and ascorbic acid oxidase. Overall,berries provide good concentrations of vitamins and minerals as part of anoverall balanced diet.

2.3 Chemical content of berries

Although berries experience many common physiological and qualitychanges throughout ripening, there are unique parameters affecting the qual-ity of each fruit. Common analyses for chemical composition of the fruitinclude individual sugars, total soluble solids, individual organic acids, totalacidity and pH, and ascorbic acid (Table 2.4 and Table 2.5). Despite thenumerous studies that have evaluated berries for chemical content amongcultivars, growing locations, harvest times, and postharvest handling prac-tices, it is often noted that intrinsic factors in the fruit was a greater distin-guishing factor than knowledge of its chemical composition. Although manyberry types are marketed, the most popular varieties in the United Statesare strawberry, blueberry, blackberry, and raspberry.



Tabl

e 2.

2

Vit

amin

Con

tent

in B

erri

es F

rom

the

U.S

. Dep

artm

ent

of A

gric

ultu

re N

utri

ent

Dat

abas

e

2

Blu

eber

ryB

lack

berr

yR

asp

berr

yB

oyse

nbe

rry

Stra

wbe

rry

Bla

ck

curr

ant

Goo

sebe

rry

Red

cu

rran

tH

uck

lebe

rry

Eld

erbe

rry

Tota

l asc

orbi

c ac

id (

mg)

9.7

2126

.23.

158

.818

127

.741

2.8

36T

hiam

in (

mg)

0.04

0.02

0.03

0.05

0.02

40.

050.

040.

040.

010.

07R

ibofl

avin

(m

g)0.

040.

030.

040.

040.

022

0.05

0.03

0.05

0.03

0.06

Nia

cin

(mg)

0.42

0.65

0.6

0.77

0.38

60.

30.

30.

10.

30.

5Pa

ntot

heni

c ac

id (

mg)

0.12

0.28

0.33

0.25

0.12

50.3

980.

286

0.064

NA

0.14

Vit

amin

B

6

(m

g)0.

050.

030.

060.

060.

047

0.066

0.08

0.07

NA

0.23

Tota

l fol

ate

(

µ

g)6

2521

6324

—6

8N

A6

Vit

amin

B

12

(

µ

g)N

DN

DN

DN

DN

DN

DN

DN

DN

DN

DV

itam

in A

(IU

)54

214

3367

1223

029

042

7960

0

a

-Toc

ophe

rol (

mg)

0.57

1.17

0.87

0.87

0.29

10.

370.

1N

AN

A

b

-Toc

ophe

rol (

mg)

0.01

0.04

0.06

NA

0.01

NA

NA

NA

NA

NA

g

-Toc

ophe

rol (

mg)

0.36

1.34

1.42

NA

0.08

NA

NA

NA

NA

NA

D

-Toc

ophe

rol (

mg)

0.03

0.9

1.04

NA

0.01

NA

NA

NA

NA

NA

Vit

amin

K (

µ

g)19

.319

.87.

87.

82.

2N

AN

A11

NA

NA

NA

, not

ava

ilabl

e; N

D, n

ot d

etec

ted

.



Tabl

e 2.

3

Min

eral

Con

tent

in B

erri

es F

rom

the

U.S

. Dep

artm

ent

of A

gric

ultu

re N

utri

ent

Dat

abas

e

2

Blu

eber

ryB

lack

berr

yR

asp

berr

yB

oyse

nbe

rry

Stra

wbe

rry

Bla

ck

curr

ant

Goo

sebe

rry

Red

cu

rran

tH

uck

lebe

rry

Eld

erbe

rry

Cal

cium

(m

g)6

2925

2716

5525

3315

38Ir

on (

mg)

0.28

0.62

0.69

0.85

0.42

1.54

0.31

10.

31.

6M

agne

sium

(m

g)6

2022

1613

2410

13N

A5

Phos

phor

us (

mg)

1222

2927

2459

2744

NA

39Po

tass

ium

(m

g)77

162

151

139

153

322

198

275

NA

280

Sod

ium

(m

g)1

11

11

21

110

6Z

inc

(mg)

0.16

0.53

0.42

0.22

0.14

0.27

0.12

0.23

NA

0.11

Cop

per

(mg)

0.06

0.17

0.09

0.08

0.04

80.0

860.

070.

107

NA

0.06

1M

anga

nese

(m

g)0.

340.

650.

670.

550.

386

0.256

0.14

40.

186

NA

NA

Sele

nium

(

m

g)0.

10.

40.

20.

20.

4N

A0.

60.

6N

A0.

6

NA

, not

ava

ilabl

e.



Tabl

e 2.

4

Che

mic

al C

onte

nts

a

Tha

t Aff

ect

Qua

lity

Cha

ract

eris

tics

of

Com

mon

Ber

ries

Sucr

ose

(%)

Glu

cose

(%)

Fru

ctos

e (%

)

°

Bri

xTo

tal s

olid

s (%

)

Asc

orbi

cac

id

(mg/

100

g)C

itri

cac

id (

%)

Mal

ic a

cid

(%

)p

HTi

trat

able

acid

ity

(%)

Nu

mbe

rof

sa

mp

les

Ref

eren

ce

Str

awb

erry

0.06

–2.2

71.

33–2

.66

2.18

–4.1

87.

1–10

.8—

37–1

040.

09–2

.03

0.12

–0.5

43.

29–3

.43

0.60

–0.9

711

44—

——

—3.

77–1

0.5

13.6

–33.

9—

——

—22

210.

11–1

.85

1.63

–2.8

22.

05–3

.30

—5.

2–8.

7—

0.45

–1.0

3—

——

1342

0.66

–1.8

00.

71–1

.71

1.23

–1.9

35.

4–9.

46.

9–10

.340

.1–8

5.3

0–0.

71—

——

645

——

—5.

8—

——

—3.

280.

531

720.

14–1

.22

0.96

–2.3

01.

46–2

.89

9.18

–13.

1—

42.7

–91.

8—

——

0.97

–1.2

06

490.

78–1

.63

1.50

–1.6

91.

84–2

.05

6.0–

8.2

——

0.55

–0.7

20.

21–0

.28

3.57

–3.5

90.

72–0

.88

347

0.53

–0.7

43.

47–8

.64

2.78

–6.2

7—

8.79

–13.

7830

1–31

30.

44–0

.75

0–0.

133.

67–3

.70

0.67

–0.7

22

48—

——

—7.

6–9.

7—

——

3.18

–3.4

90.

91–1

.07

634

Ras

pb

erry

——

—9.

26–1

0.54

14.6

9–17

.98

21.3

–31.

11.

27–1

.78

0.13

–0.1

82.

65–2

.88

1.67

–2.3

24

69—

——

14.2

–14.

815

.4–3

2.0

——

2.85

–3.0

61.

90–2

.52

570

——

—10

.0–1

3.0

—16

.1–2

8.9

——

2.78

–3.0

31.

71–2

.30

771

——

—10

.5–1

3.0

—11

.8–2

8.8

——

3.20

–3.4

50.

16–0

.29

873

——

—9.

26–1

0.5

15.2

–17.

921

.3–3

1.1

1.27

–1.7

80.

13–0

.18

2.88

–3.8

7—

469

——

—9.

7–10

.9—

2.99

–3.0

81.

75–2

.38

374

(

Con

tinu

ed

)



Tabl

e 2.

4 (C

onti

nued

)

Che

mic

al C

onte

nts

a

Tha

t Aff

ect

Qua

lity

Cha

ract

eris

tics

of

Com

mon

Ber

ries

Sucr

ose

(%)

Glu

cose

(%

)Fr

uct

ose

(%)

°

Bri

xTo

tal

solid

s (%

)

Asc

orbi

cac

id

(mg/

100

g)C

itri

cac

id (

%)

Mal

ic a

cid

(%)

pH

Titr

atab

leac

idit

y (%

)

Nu

mbe

rof

sa

mp

les

Ref

eren

ce

Bla

ckb

erry

0.12

–0.2

61.

58–2

.61

2.11

–3.3

8—

——

—0.

06–1

.10

——

563

——

——

—18

.0—

——

—1

46—

——

——

12.4

–13.

1—

——

—7

75—

——

—8.

20–1

3.6

——

——

0.84

–2.6

211

65—

——

10.8

–11.

4—

12.7

–38.

7—

—3.

06–3

.20

0.16

–0.3

05

73—

——

——

——

—2.

55–4

.28

1.02

–4.2

211

64

Blu

eber

ry

0.12

–1.1

43.

28–3

.87

3.34

–3.8

8—

——

——

——

257

——

——

——

—0.

06–1

.10

——

563

a

Val

ues

are

for

who

le f

ruit

at

thei

r m

axim

al o

r op

tim

al s

tage

of

ripe

ness

or

are

star

ting

con

cent

rati

ons

if f

ruit

is p

roce

ssed

or

held

in s

tora

ge.



2.3.1 Strawberry

The popularity and worldwide demand for fresh and processed strawberrieshave made them one of the most extensively researched berries in the world.The quality of fresh strawberries as a function of their chemical compositionand organoleptic attributes is an important area of study. Ford et al.

30

dem-onstrated that the quality of strawberries is the most important factor influ-encing retail sales, and they indicated that simple screening factors for com-pounds influencing taste and aroma can be critical for consumer acceptance.Considerable research has been dedicated to evaluate breeding lines andcommercial cultivars over several seasons and growing locations to establishboth intrinsic and extrinsic factors that relate to optimal fruit quality.

31,32

Chandler et al.

33

noted that strawberries with higher soluble solids are gen-erally preferred over lower soluble solids, thus optimizing fruit qualitythrough selection of those lines with optimal sugar and acid balance, anddesirable aroma characteristics are critical for consumer preference.

34

Straw-berries are widely considered to be a good dietary source of vitamins andminerals, yet concentrations can vary greatly among cultivars and withpostharvest handling conditions. High concentrations of ascorbic acid, potas-sium, magnesium, iron, zinc, and calcium have been reported in six varietiesof strawberries.

35

Ascorbic acid was found to increase continuously duringstrawberry maturation

7

and its concentrations are highly influenced by post-harvest handling practices, the presence of oxidase enzymes, and the con-ditions of storage. As an antioxidant, ascorbic acid was shown to accountfor about 15% of the total antioxidant capacity,

36

with polyphenolics account-ing for the remainder.

Environmental conditions during strawberry growth, especially atmo-spheric temperature, has been identified as among the most critical factorsinfluencing strawberry fruit quality. Since growing conditions continuouslychange throughout the season, considerable variation can exist in chemicalcomposition in response to temperature and light exposure. Olsson et al.

32

reported significant differences in concentrations of polyphenolics, ascorbicacid, and antioxidant capacity among strawberry cultivars, with differencesin growing temperature affecting soluble solids content. Atmospheric tem-peratures and solar radiation were also found to be critical factors affectingchemical composition, with Hellman and Travis

37

and Chandler et al.

33

observing that as growing temperatures increased, a general decrease in fruitquality was observed. These effects were especially true for winter produc-tion strawberries, where Del Pozo-Insfran et al.

21

showed the appreciableeffects that cultivar, harvest date, and production year had on sugar,polyphenolics, and antioxidant content in 22 strawberry lines. In this study,high soluble solids and low polyphenolic content characterized fruit har-vested in early season conditions (11.4

°

C average temperature), whereas laterharvests (15.9

°

C average temperature) were characterized by appreciablyhigher polyphenolics, sugar, and ascorbic acid concentrations. Wang andCamp

38

showed similar effects, where higher day/night growth temperatures



(25

°

C/12

°

C) enhanced the development of anthocyanins and decreased solublesolids, organic acids, and ascorbic acid compared to lower temperatures(18

°

C/12

°

C). Likewise, Wang and Zheng

39

showed that fruits grown in lowertemperature environments contained lower concentrations of several classesof polyphenolics that affected antioxidant capacity.

The bright red color of strawberries is an initial distinguishing factor forconsumers in judging quality and the perception of flavor. Strawberries areconsidered mature when their red color reaches in excess of two-thirds of thefruit surface, with approximately 7% soluble solids.

40

However, it was reportedthat no single parameter, such as soluble solids or color, relates to overall fruitquality and that even multiple assays for chemical composition are oftenlimited in characterizing the flavor and quality of the fruit.

41–43

Berry flavor isa complex interaction among chemical attributes, including sugars, acids, andvolatiles,

31

yet when quantified, these parameters still may not directly relateto consumers’ perception of fruit quality. Like all berries, strawberries have alimited shelf life, with significant microbial decay, fruit softening, water loss,loss of red color, brown pigment formation, and flavor changes. Therefore, itis critical to evaluate numerous fruits, growing locations, and harvest timesfor chemical composition, organoleptic attributes, and handling regimes togain a better understanding of those factors impacting consumer acceptability.

Numerous studies have demonstrated the effects of breeding lines andcultural practices on changes in the chemical composition of strawberries.The chemical composition of nine hybrids and two varieties of strawberrieswere evaluated during ripening (green, pink, and red) and it was found thatsugars and ascorbic acid increased, whereas organic acid changes werehighly genotype dependent and did not show a clear trend over time.

44

Simple sugars such as glucose, fructose, and sucrose account for nearly allof the soluble carbohydrates in strawberries,

31

with glucose and fructose thepredominate sugars, at approximately the same ratio throughout ripening.Montero et al.

7

monitored the sugar and acid content of strawberriesthroughout development (fruit set through senescence), with a maximumsucrose content found at 21 to 28 days of development with a subsequentincrease in glucose, fructose, and ascorbic acid as the fruit matured. How-ever, throughout development only small differences were observed in pHand titratable acidity despite an overall increase in malic, citric, and shikimicacids. Sturm et al.

42

found that individual sugars (sucrose, glucose, fructose,and xylose) and organic acids (citric, fumaric, and shikimic acids) in 13strawberry lines at two ripeness stages were highly variable among varieties,yet it was these parameters in relation to optimal harvest time that had thegreatest impact on consumer acceptability. The change in sugars from apreponderance of sucrose in early fruit development through the full ripestage to an overall predominance of glucose and fructose is a strong indica-tion of sucrose hydrolysis from the activity of invertase as fruit ripens andduring postharvest storage. The varying sensory perception of these sugars,along with relatively small changes in organic acids, serves to alter thesugar/acid balance, enhancing the perception of sweetness.



Postharvest and storage conditions can greatly impact the chemical com-position of berries, so storage conditions must be developed and controlledfor each berry type. Cordenunsi et al.

45

evaluated the chemical parametersof strawberries over 1 week of storage at 6

°

C. Although storage differencesamong cultivars were significant, compositional changes affecting pH andtitratable acidity were minimal, sucrose was lost after 2 days, and a loss ofup to 50% of ascorbic acid was observed. Strawberries held in high concen-trations of carbon dioxide (10% to 30%) and variable oxygen concentrationsshowed losses of ascorbic acid were enhanced by long-term storage com-pared to a greater retention in black currants and blackberries.

46

However,the postharvest quality of strawberries measured for sugars, acids, andaroma active compounds impacting flavor following 9 to 13 days of storagein air or 20 kPa carbon dioxide revealed better overall quality in the highcarbon dioxide atmosphere.

47

Postharvest practices and minimal processingof strawberries show a variable response depending on the severity of phys-ical wounding and the cultivar. Castro et al.

48

demonstrated that whole andcapped strawberries held for up to 3 days under refrigerated storage condi-tions maintained their chemical composition, while cut pieces (3 to 18 mm)experienced a 26% to 50% loss in ascorbic acid within 5 minutes. Likewise,Nunes et al.

49

evaluated strawberries 1 week after 0 and 6 hour delays inpostharvest cooling and found the delay caused enhanced water loss,reduced texture, and lowered titratable acidity with a subsequent loss ofascorbic acid, total soluble solids, and sugars. Overall, these results demon-strated that improper handling and storage can have adverse effects on thechemical composition, quality, and nutritional content of berries.

Changes in cell wall composition and physical characteristics as relatedto fruit texture and consumer acceptance are important quality factors forstrawberries. Beyond simple desiccation of the fruit during prolongedstorage, cell wall depolymerization during maturation occurs despite lowpolygalactouronase content in strawberries.

50

As fruit develops and matures,textural changes are influenced by the amount of water uptake,

51

expandingcell volume,

52

cell wall composition,

53,54

the presence of metals such ascalcium,

55

and the action of cell wall degrading enzymes. Strawberries ofoptimal quality have a soft texture due to ripening-induced softening, butexcessive depolymerization of high molecular weight pectins and the sub-sequent formation of smaller, water soluble subunits are associated withdecreased quality characteristics. Rosli et al.

12

compared the polysaccharidecontent of three strawberry cultivars during ripening and found that watersoluble polysaccharides formed continuously until the beginning of colorformation, while both cellulose and hemicellulose continuously decreasedwith ripening. Cell wall polysaccharides were evaluated during strawberryripening in two tissue types, with increased formation of water soluble pectinformed in cortical tissue compared to pith tissue, with a 94% decrease infirmness from the final stages of fruit development through complete ripeningand a 75% average decrease in alcohol insoluble polysaccharides.

56

Huber

53

suggests that pectin biosynthesis occurs during strawberry ripening, with



textural differences being due to loose binding to the cell wall that may resultin enhanced solubilization during storage. However, changes in polysaccha-ride solubility are also attributed to enzyme action that promotes fruit soften-ing. This role was demonstrated by Vicente et al.,

11

where strawberries wereheated to 45

°

C for 3 hours and stored at 20

°

C for 2 days, revealing that heatedfruit had a firmer texture than unheated fruit due to the inhibition of

β

-glucanase,

β

-xylosidase,

β

-glactosidase, and polygalactouronase, while activatedpectin methyl esterase (PME) enhanced metal ion cross-linkages in the pectin.

2.3.2 Blueberry

Blueberries, along with strawberries, are among the most popular berries inretail markets and are sold in numerous fresh, frozen, and processed formsfor a variety of food applications. Considerable research has been conductedon the phytochemical content and potential health benefits of blueberries,but the fruit is also distinguished for its sweet, aromatic flavor, high dietaryfiber, and low fat. The sugar content of ripe blueberries as evaluated byKader et al.57 and Ayaz et al.58 was an equal ratio of glucose and fructose,providing an indication of invertase activity as the fruit ripened. The con-centrations of organic acids were also found to increase during ripening,where quinic, citric, and malic acids predominate in ripe fruit.58 Blueberriesare also susceptible to quality deterioration due to the action of oxidaseenzymes, where polyphenol oxidase and peroxidase are reported to increaseas the fruit ripens.59,60 The cell wall composition and resulting texture ofblueberries is an important quality parameter,61 and their smooth skin sur-face and waxy cuticle experience less damage during harvest in relation toother berries. However, the increased popularity and market demand forblueberries, coupled with the limited availability of labor, has resulted inmore machine-harvested fruit.62 Mechanical harvesters are not selective forunripe or decayed fruit and can damage and bruise the fruit; thus the needfor a postharvest sorting step to ensure optimal fruit quality.

2.3.3 Blackberry

Numerous parallels exist among the different berry types with regard tofactors influencing composition and quality. The quality and organolepticcharacteristics of blackberries are also highly dependent on their content andcomposition of sugars and acids. Kafkas et al.63 evaluated five blackberrylines for sugar, acid, and ascorbic acid composition and found fructose asthe primary sugar and malic acid as the primary organic acid, but little orno ascorbic acid was present. Ethylene was found to be influential in black-berry detachment from the plant, but was not influential in fruit ripening,as soluble solids increase and titratable acidity decreases throughout theripening process.17 The sucrose present in unripe blackberries is also quicklyconverted to glucose and fructose as the fruit ripens, with often less than1% remaining in fully ripe fruit. In 11 blackberry lines harvested over dif-ferent growing seasons and two geographic locations, Reyes-Carmona et al.64



found that genotypic differences in fruit composition for total acidity, ascor-bic acid, soluble solids, and polyphenolics were greater than the effects ofseason or climate at the harvest sites. An increase in soluble solids contentand a decrease in titratable acidity in two varieties of blackberries wasobserved during ripening that changed the sugar:acid ratio by 10-fold withan overall increase in antioxidant phytochemical composition.65 Blackberriesexhibited a 60% decrease in acidity as they ripened from 50% color devel-opment to full ripeness, with a subsequent increase in soluble solids andpH, and did not exhibit major changes in solids, acidity, or texture after beingheld in storage for 7 days at 2°C.66

2.3.4 Raspberry

The optimum quality characteristics for raspberries are similar to those ofblackberries as related to an appropriate harvest time to obtain maximalcolor and flavor in relation to desired fruit texture. The ripening of raspber-ries was found to be enhanced by ethylene when exogenously applied, buta classical response exhibiting a rapid increase in respiration was notfound.67,68 As in other berries, the cell wall composition of raspberries appre-ciably changes with ripening, with a decrease in both cellulose and pectinobserved from enzyme-induced hydrolytic reactions.16 Anthocyanin devel-opment in raspberries is also critical for quality considerations, and fruitcolor is attributable in part to the content and concentration of organic acids,such as citric and malic acid, that affect the visible color characteristics.69 Infive raspberry cultivars held for 1 week under controlled atmosphere con-ditions (10% oxygen and 15% or 31% carbon dioxide), Haffner et al.70 showedthat the total soluble solids were unaffected and titratable acidity decreased,but the response of ascorbic acid varied greatly among the cultivars. How-ever, in processed raspberry pulps, ascorbic acid concentrations decreasedsteadily over time in a temperature-dependent manner that was consistentwith the loss of anthocyanins.71

2.4 ConclusionNumerous factors affect the chemical composition and quality characteristicsof berry fruits. Despite the numerous changes that occur in the fruit through-out ripening, consumers generally consume fully ripe fruit that are charac-terized by their high content of simple sugars, such as sucrose, glucose, andfructose, where the sweetness is most commonly counterbalanced by citricand malic acids. The color of the fruit is critical for initial consumer accept-ability, but is quickly replaced by sweetness and a firm texture upon con-sumption. Although there are obvious color, taste, and textural differencesamong the various berry types, they follow similar trends in developmentand ripening to produce high-quality fruits that are good sources of numer-ous vitamins and minerals important for human health. Among fruit culti-vars, it is apparent that there are numerous intrinsic factors affecting quality



and consumer acceptance that are not fully defined by the chemical contentof the fruit. However, without extensive organoleptic evaluations of berrycultivars over numerous growing locations and harvest seasons, chemicalanalysis of their color substances, sugars, acids, and textural properties willcontinue to be used to define the quality of berry fruits.

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4. Shaw, D.V., Genotypic variation and genotypic correlation for sugars andorganic acids of strawberries, J. Am. Soc. Hort. Sci., 113, 770, 1988.

5. Souleyre, E.J.F., Iannetta, P.P.M., Ross, H.A., Hancock, R.D., Shepherd, L.V.T.,Viola, R., Taylor, M.A., and Davies, H.V., Starch metabolism in developingstrawberry (Fragaria × ananassa) fruits, Physiol. Plant., 21, 369, 2004.

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28. Timberlake, C., Metallic components of fruit juices: III. Oxidation and stabilityof ascorbic acid in model systems resembling blackcurrant juice, J. Sci. FoodAgric., 11, 258, 1960.

29. Lee, S.K. and Kader, A.A., Preharvest and postharvest factors influencing vita-min C content of horticultural crops, Postharvest Biol. Technol., 20, 207, 2000.

30. Ford, A., Hansen, K., Herrington, M., Moisander, J., Nottingham, S., Prytz, S.,and Zorin, M., Subjective and objective determination of strawberry quality,Acta Hort. (ISHS), 439, 319, 1997.

31. Cordenunsi, B.R., Nascimento, J.R.O., Genovese, M.I., and Lajolo, F.M., Influ-ence of cultivar on quality parameters and chemical composition of straw-berry fruits grown in Brazil, J. Agric. Food Chem., 50, 2581, 2002.

32. Olsson, M.E., Ekvall, J., Gustavsson, K.-E., Nilsson, J., Pillai, D., Sjöholm, I.,Svensson, U., Akesson, B., and Nyman, M.G.L., Antioxidants, low molecularweight carbohydrates, and total antioxidant capacity in strawberries (Fragaria× ananassa): effects of cultivar, ripening, and storage, J. Agric. Food Chem., 52,2490, 2004.

33. Chandler, C.K., Herrington, M., and Slade, A., Effect of harvest date on solublesolids and titratable acidity in fruit of strawberry grown in a winter, annualhill production system, Acta Hort., 626, 353, 2003.

34. Shamaila, M., Baumann, T.E., Eaton, G.W., Powrie, W.D., and Skura, B.J.,Quality attributes of strawberry cultivars grown in British Columbia, J. Food.Sci., 3, 696, 720, 1992.



35. Hakala, M., Lapvetelainen, A., Huopalahti, R., Kallio, H., and Tahvonen, R.,Effects of varieties and cultivation conditions on the composition of straw-berries, J. Food Comp. Anal., 16, 67, 2003.

36. Wang, H., Cao, G., and Prior, R.L., Total antioxidant capacity of fruits, J. Agric.Food Chem., 44, 701, 1996.

37. Hellman, E.W. and Travis, J.D., Growth inhibition of strawberry at high tem-peratures, Adv. Strawberry Prod., 7, 36, 1998.

38. Wang, S.Y. and Camp, M.J., Temperatures after bloom affect plant growth andfruit quality of strawberry, Sci. Hort., 85, 183, 2000.

39. Wang, S.Y. and Zheng, W., Effect of plant growth temperature on antioxidantcapacity in strawberry, J. Agric. Food Chem., 49, 4977, 2001.

40. Kader, A.A., Fruit maturity, ripening, and quality relationships, Acta Hort.(ISHS), 485, 203, 1999.

41. Garcia, J.M., Herrera, S., and Morilla, A., Effects of postharvest dips in calciumchloride on strawberry, J. Agric. Food Chem., 44, 30, 1996.

42. Sturm, K., Koron, D., and Stampar, F., The composition of fruit of differentstrawberry varieties depending on maturity stage, Food Chem., 83, 417, 2003.

43. Perez, A.G., Olias, R., Espada, J., Olias, J.M., and Sanz, C., Rapid determina-tion of sugars, non-volatile acids and ascorbic acids in strawberry and otherfruits, J. Agric. Food Chem., 45, 3545, 1997.

44. Kafkas, E., et al., Quality characteristics of strawberry genotypes at differentmaturation stages, Food Chem., 100, 122, 2007.

45. Cordenunsi, B.R., Nascimento, J.R.O., and Lajolo, F.M., Physico-chemicalchanges related to quality of five strawberry fruit cultivars during cool-stor-age, Food Chem., 83, 167, 2003.

46. Agar, I.T., Streif, J., and Bangerth, F., Effect of high CO2 and controlled atmo-sphere (CA) on the ascorbic and dehydroascorbic acid content of some berryfruits, Postharvest Biol. Technol., 11, 47, 1997.

47. Pelayo, C., Ebeler, S.E., and Kader, A.A., Postharvest life and flavor qualityof three strawberry cultivars kept at 5°C in air or air + 20 kPa CO2, PostharvestBiol. Technol., 27, 171, 2003.

48. Castro, I., Gonçalves, O., Teixeira, J.A., and Vicente, A.A., Comparative studyof Salva and Camorosa strawberries for the commercial market, J. Food Sci., 67,2132, 2002.

49. Nunes, M.C.N., Brecht, J.K., Morais, A.M.M.B., and Sargent, S.A., Physicaland chemical quality characteristics of strawberries after storage are reducedby a short delay to cooling, Postharvest Biol. Technol., 6, 17, 1995.

50. Nogata, Y., Ohta, H., and Voragen, A.G.J., Polygalactouronase in strawberryfruit, Phytochemistry, 34, 867, 1993.

51. Knee, M., Sargent, J.A., and Osborne, D.J., Cell wall metabolism in developingstrawberry fruit, J. Exp. Bot., 28, 377, 1977.

52. Manning, K., Soft fruits, in Biochemistry of Fruit Ripening, Seymour, G.B.,Taylor, J.E., and Tucker, G.A., Eds., Chapman & Hall, London, 1993, p. 347.

53. Huber, D.J., Strawberry fruit softening: the potential roles of polyuronidesand hemicelluloses, J. Food Sci., 49, 1310, 1984.

54. Schieber, A., Fügel, R., Henke, M., and Carle, R., Determination of the fruitcontent of strawberry fruit preparations by gravimetric quantification ofhemicellulose, Food Chem., 91, 365, 2005.

55. Legentil, A., Guichard, I., Piffaut, B., and Haluk, J., Characterization of strawberrypectin extracted by chemical means, Lebensm. - Wiss. + Technol., 28, 569, 1995.



56. Koh, T.H. and Melton, L.D., Ripening-related changes in cell wall polysac-charides of strawberry cortical and pith tissues, Postharvest Biol. Technol., 26,23, 2002.

57. Kader, F., Rovel, B., and Metche, M., Role of invertase in sugar content inhighbush blueberries (Vaccinium corymbosum, L.), Lebensm. - Wiss. + Technol.,26, 593, 1993.

58. Ayaz, F.A., Kadioglu, A., Bertoft, E., Acar, C., and Turna, I., Effect of fruitmaturation on sugar and organic acid composition in two blueberries(Vaccinium arctostaphylos and V. myrtillus) native to Turkey, N. Z. J. Crop Hort.Sci., 29, 137, 2001.

59. Miesle, T.J., Proctor, A., and Lagrimini, L.M., Peroxidase activity, isoenzymes,and tissue localization in developing highbush blueberry, J. Am. Soc. Hort.Sci., 116, 827, 1991.

60. Kader, F., Rovel, B., Girardin, M., and Metche, M., Mechanism of browningin fresh highbush blueberry fruit (Vaccinium corymbosum L): partial purifica-tion and characterisation of blueberry polyphenol oxidase, J. Sci. Food Agric.,73, 513, 1997.

61. Silva, J.L., Marroquin, E., Matta, F.B., Garner, J.O., and Stojanovic, J., Physico-chemical, carbohydrate and sensory characteristics of highbush and rabbiteyeblueberry cultivars, J. Sci. Food Agric., 85, 1815, 2005.

62. Mainland, C.M., Kushman, L.J., and Ballinger, W.E., The effect of mechanicalharvesting on yield, quality of fruit, and bush damage of highbush blueberry,J. Am. Soc. Hort. Sci., 100, 129, 1975.

63. Kafkas, E., Kosar, M., Turemis, N., and Baser, K.H.C., Analysis of sugars,organic acids and vitamin C contents of blackberry genotypes from Turkey,Food Chem., 97, 732, 2006.

64. Reyes-Carmona, J., Yousef, G.G., Martinez-Peniche, R.A., and Lila, M.A., An-tioxidant capacity of fruit extracts of blackberry (Rubus sp.) produced indifferent climatic regions, J. Food Sci., 70, 497, 2005.

65. Siriwoharn, T., Wrolstad, R.E., Finn, C.E., and Pereira, C.B., Influence of cul-tivar, maturity, and sampling on blackberry (Rubus L. hybrids) anthocyanins,polyphenolics, and antioxidant properties, J. Agric. Food Chem., 52, 8021, 2004.

66. Perkins-Veazie, P., Collins, J.K., and Clark, J.R., Changes in blackberry fruitquality during storage, Acta Hort., 352, 87, 1993.

67. Perkins-Veazie, P. and Nonnecke, G., Physiological changes during ripeningof raspberry fruit, HortScience, 27, 331, 1992.

68. Iannetta, P.P.M., van den Berg, J., Wheatley, R.E., McNicol, R.J., and Davies,H.V., The role of ethylene and cell wall modifying enzymes in raspberry(Rubus idaeus) fruit ripening, Physiol. Plant., 105, 338, 1999.

69. Ancos, B., Gonzales, E., and Cano, M.P., Differentiation of raspberry varietiesaccording to anthocyanin composition, Z. Lebensm. Unters. Forsch. A, 208, 33, 1999.

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71. Ochoa, M.R., Kesseler, A.G., Vullioud, M.B., and Lozano, J.E., Physical andchemical characteristics of raspberry pulp: storage effect on composition and color,Lebensm. − Wiss. + Technol., 32, 149, 1999.

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73

chapter 3

Berry fruit phytochemicals

Luke R. Howard and Tiffany J. Hager

Contents

3.1 Introduction ................................................................................................. 743.2 Phenolic composition of berry fruit......................................................... 74

3.2.1 Phenolic acids and their derivatives........................................... 743.2.2 Ellagitannins and ellagic acid derivatives ................................. 763.2.3 Anthocyanins .................................................................................. 793.2.4 Flavonols.......................................................................................... 853.2.5 Proanthocyanidins.......................................................................... 87

3.3 Phenolic content of berry fruit ................................................................. 893.3.1 Raspberry......................................................................................... 893.3.2 Strawberry ....................................................................................... 913.3.3 Blackberry........................................................................................ 923.3.4 Blueberry ......................................................................................... 923.3.5 Antioxidant capacity of berry fruit ............................................. 933.3.6 Relationships between phenolic classes

and antioxidant capacity............................................................... 963.3.7 Contribution of individual flavonoids

to antioxidant capacity .................................................................. 963.4 Other phytochemicals in common berry fruit ....................................... 97

3.4.1 Lignans............................................................................................. 973.4.2 Sterols ............................................................................................... 983.4.3 Stilbenes ........................................................................................... 98

3.5 Conclusion.................................................................................................... 98References .............................................................................................................99



3.1 Introduction

Common berry fruits, including blackberries (

Rubus

sp.), strawberries(

Fragaria

×

ananassa

), and black raspberries (

Rubus occidentalis

), red raspber-ries (

Rubus idaeus

), and blueberries (

Vaccinium

spp.), have long been appre-ciated for their dessert-like quality. Berry fruits have appealing colorsimparted by anthocyanin pigments that range from red to purple to black,in addition to unique tastes and aromatic notes. They contain importantmicronutrients such as vitamin C and folic acid are considered excellentsources of dietary fiber. Recently much attention has focused on natural plantcompounds with bioactive properties called phytochemicals that may affordprotection against chronic diseases. Berry fruits are a rich source of phy-tochemicals, in particular phenolic compounds, which are reported to havea range of potential anti–cancer and antiheart disease that were reviewedby Beattie et al.

1

, and are the subject of Chapter 6.

3.2 Phenolic composition of berry fruit

Berry fruit are a rich source of polyphenols, especially flavonoids (anthocy-anins, flavonols, flavan-3-ols, and proanthocyanidins) and ellagitannins.Many hydroxybenzoic and hydroxycinnamic acid derivatives are alsopresent in the fruit. Due to genetic differences, which are most apparent invariations in fruit color, berry fruit vary significantly in both phenolic com-position and content.

3.2.1 Phenolic acids and their derivatives

The predominant phenolic acids in berry fruit are the hydroxybenzoic andhydroxycinnamic acids (Figure 3.1). Although ellagic acid is a hydroxyben-zoic acid, most of the ellagic acid in berries is present in forms known asellagitannins, which constitute a separate class of phenolics. The hydroxy-benzoic and hydroxycinnamic acids rarely occur as free acids, but are com-monly found in conjugated forms as esters and glycosides. They may befound in the vacuole in soluble form or be insoluble as a result of linkagewith cell wall polysaccharides. Phenolic acids are commonly analyzed byhigh performance liquid chromatography (HPLC) after an acid or alkalinehydrolysis step. Although this technique has allowed researchers to identifythe major phenolic acid—aglycones—in berries, limited information is avail-able on the native ester and glycoside forms present in the fruit.

In strawberries,

p

-coumaric,

2–5

t

-cinnamic,

4,6

p

-hydroxybenzoic,

4,5

caffeic,

4

vanillic,

4

protocatechuic,

4

and 5-caffeoylquinic (chlorogenic acid)

4

acids havebeen identified following acid or base hydrolysis. Specific hydroxybenzoicand hydroxycinnamic acids identified in the fruit include glucose esters ofcaffeic,

7

p

-coumaric,

7,8

ferulic,

7

and gallic acids,

7

and the

β

-

D

-glucosides of

p

-coumaric

7,8

and

p

-hydroxybenzoic acids.

7

The glucose ester of

p

-coumaricacid is one of the major phenolic acids present in the fruit,

7,9–11

and is uniformly


Chapter 3: Berry fruit phytochemicals 75

distributed throughout the skin and flesh.

10

Other predominant phenolicacids include 5-caffeoylquinic and

p


4

In blackberries, the hydroxybenzoic acids—

p

-hydroxybenzoic, protocat-echuic, gallic, gentisic, salicylic, and vanillic—are present in free, ester, andglycoside forms, with the ester and glycoside forms of salicylic acid predom-inating.

12

The hydroxycinnamic acids—caffeic,

m

-coumaric,

p

-coumaric, andferulic—are also present in free, ester, and glycoside forms, with the esterforms of

m

-coumaric, 3,4-dimethoxycinnamic, and hydroxycaffeic, and theglycoside forms of 3,4-dimethoxycinnamic and hydroxycaffeic predominat-ing.

12

Esters and glycosides account for 53.1% and 43.6%, respectively, oftotal phenolic acids, while free acids account for only 3.3%.

12

Specific hydrox-ybenzoic and hydroxycinnamic acid derivatives identified in blackberriesinclude chlorogenic acid (5-caffeoylquinic acid), neochlorogenic acid (3-caffeoylquinic acid), 3-

p

-coumaroylquinic acid, 3-feruolylquinic acid, glucoseesters of caffeic,

p

-coumaric, ferulic, and gallic acids, and the

β

-

D

-glucosidesof

p

-coumaric,

p

-hydroxybenzoic, and protocatechuic acids.

7

The phenolic acids identified in red raspberries following acid or basehydrolysis include

p

-coumaric,

3,4

caffeic,

3,4

ferulic,

3

gallic,

3

5-caffeoylquinic,

4

Figure 3.1

Structures of various (A) hydroxybenzoic and (B) hydroxycinnamic acids.

R3

R2

R1

OH

O

Hydroxybenzoic Acids Acids R1 R2 R3 p-Hydroxybenzoic Acid H OH H Protocatechuic Acid H OH OH Vanillic Acid CH3O OH H Syringic Acid CH3O OH CH3OGallic Acid OH OH OH

R3

R2

R1

R4

O

Hydroxycinnamic Acids Acid R1 R2 R3 R4 m-Coumaric OH H H OH p-Coumaric H OH H OH Caffeic H OH OH OH Ferulic CH3O OH H OH Sinapic CH3O OH CH3O OH Caffeoylquinic H OH OH Quinic acid Coumaroylquinic OH H H Quinic acid

B.

A.



p

-hydroxybenzoic,

4

vanillic

4

and protocatechuic

4

acids. Specific phenolic acidderivatives identified in red raspberries include 5-

p

-coumaroylquinic acid;glucose esters of caffeic,

p

-coumaric, and ferulic acids; and the

β

-

D

-glucosidesof caffeic,

p

-coumaric, ferulic, and

p


7

Raspberries areunique compared to other berries because they contain appreciable levels of

p

-hydroxybenzoic acid glucoside.

7

In blueberries, the hydroxybenzoic acids—gentisic, gallic, protocate-chuic, salicylic, syringic, and vanillic—are present in free, ester, and glycosideforms, with the ester and glycoside forms of salicylic acid predominating.

12

The hydroxycinnamic acids—caffeic,

m

-coumaric,

o

-coumaric,

p

-coumaric,and ferulic—are also present in free, ester, and glycoside forms, with sinapicand 3-4-dimethoxycinnamic acids present in the ester and glycoside forms,and dihydroxycinnamic acid present in the ester form.

12

According toZadernowski et al.,

12

p

-coumaric acid is the predominant hydroxycinnamicacid derivative in the ester form, excluding chlorogenic acid (5-

O

-caffeoylquinicacid), which was not identified in the study due to degradation during alkalinehydrolysis, while 3,4-dimethoxycinnamic and hydroxycaffeic acids are thepredominant glycosides. Glycosides and esters account for 56.7% and 40.7%,respectively, of total phenolic acids, while free acids account for only 2.6%.

12

Chlorogenic acid (5-

O

-caffeoylquinic acid) is the predominant hydroxycin-namic acid ester found in blueberries and is the single most abundant polyphe-nolic compound found in the fruit.

13,14

Besides chlorogenic acid, specifichydroxybenzoic and hydroxycinnamic acid derivatives identified in blueber-ries include neochlorogenic acid (3-caffeoylquinic acid), 5-

p

-coumaroylquinic,5-feruoylquinic acid, and the

β

-

D

-glucosides of caffeic,

p

-coumaric, ferulic,

p

-hydroxybenzoic, protocatechuic, and gallic acids.

7

3.2.2 Ellagitannins and ellagic acid derivatives

Berries are a rich source of hydrolysable tannins, specifically ellagitannins,which vary significantly in molecular weight (Figure 3.2). Berry ellagitanninsconsist of a glucose core esterified with hexahydroxydiphenic acid (HHDP).Upon acid or base hydrolysis of ellagitannins, HHDP spontaneously rear-ranges to a dilactone form known as ellagic acid. In addition to ellagitannins,berry fruit also contain ellagic acid in free, acylated, and glycosylated forms.Because of the diversity of ellagitannins and ellagic acid derivatives in ber-ries, many studies have reported the total ellagic content of berries followingacid hydrolysis, with results expressed as ellagic acid equivalents. Recentlyseveral ellagitannins and ellagic acid derivatives have been identified inberries using high performance liquid chromatography mass spectrometry(HPLC-MS).

In red raspberries, the ellagitannins lambertianin-C and sanguiin H-6have been identified in several studies,

15–17

along with sanguiin H-10.

15,17

Theellagic acid derivatives identified include the 4-arabinoside,

18

4-acetylxyloside,and 4-acetylarabinoside.

15,17,18

Based on peak intensity and mass counts,sanguiin H-6 appears to be the predominant ellagitannin, followed by



(a)

Figu

re 3

.2

Stru

ctur

es o

f ga

llic

acid

, ella

gic

acid

, and

var

ious

ella

gita

nnin

s.

OH

OH

OH

OO

H

O

O

OH

OH

OH

OH

O

O

OH

OH

OH

OH

OH

O

OH

O

OH

OH

OH

OH

OH

OH

O

O

O

O

O

O

R1

Ella

gita

nnin

R

1 M

olec

ular

Wei

ght

Cas

uari

ctin

-O

G

934.

69

Pote

ntil

lin

-OG

93

4.69

Pe

dunc

ulag

in

OH

78

2.58

Gal

licac

id (

MW

: 170

.12)

Ella

gic

acid

(M

W: 3

02.2

0)



lambertianin-C.

15–17

Ellagic acid arabinoside is the major ellagic acid deriv-ative in the fruit (2 mg/100 g fresh weight [FW]), with less than 1 mg/100 gFW of 4-acetylxyloside and 4-acetylarabinoside reported.

18

Ellagitanninsdecrease markedly as fruit ripen,

16

and different varieties have been shownto vary significantly in concentration.

16,19

The ellagitannins identified in strawberries include casuarictin,

20

sanguiinH-6, and HHDP.

8

Määtä-Riihinen et al.

19

tentatively identified three peaksas ellagitannins based upon HPLC-MS data and reported a total concentra-tion of 18 mg/100 g FW. They observed no ellagic acid derivatives in thefruit, but found ellagic acid in free form at a concentration of 4 mg/100 gFW. In contrast, Seeram et al.

8

identified two peaks as isomeric forms ofmethyl ellagic acid pentose conjugates and tentatively identified three addi-tional peaks as ellagic acid-based compounds. Besides sanguiin H-6 andcasuarictin, potentillin and pedunculagin have been identified in strawberryleaves,

21

suggesting they may be present in the fruit. Although achenescontain higher levels of ellagic acid than pulp,

11,22,23

the achenes only accountfor about 1% to 5% of the fruit mass. Accordingly, 95% of the ellagic acidresides in the pulp, while only 4% is contained in the seeds.

24

The ellagitannins identified in blackberry fruit include potentillin andphenolic ester T1, which appears to be sanguiin H-6 based upon its massspectral data.

25

Pedunculagin and casuaricitin have been identified in blackberry

Figure 3.2

(Continued).

OH

OO

OH

OH

OH

OH

OHO

O

O

O

O

OH

OH

OH

OH

OHOOO

O

OO

OH

OH

OH

OHOH

OH

O

OO

OHOH

OO

O

OH

OH

OH

OHOH

OH

O

O

O

O

OH

OH

OH

OH

Sanguiin H-6 (MW:1871.31)

Lambertianin C (MW: 2805.96)

OH

OH

OH

OH

OHO

O

O

O

OHOH

OH

OO

O

OH

OH

OH

OHOH

OH

O

O

O

O

OHOOH

OH

OO

OH

OH

OH

OH

OHO

O

O

O

O

OH

OH

OH

OH

OHOOO

O

OO

OH

OH

OH

OHOH

OH

O

OO

OHOH

OO

O

OH

OH

OH

OHOH

OH

O

O

O

O

OH

OH



leaves and shoots, suggesting they may be present in the fruit.

25

The ellagi-tannins and ellagic acid derivatives in blackberries are present predomi-nantly in the seeds

26

and the fruit contain much higher levels of ellagitannins(51.1 to 68.2 mg/100 g) than ellagic acid derivatives (1.2 to 3.0 mg/100 g).

27

The majority of ellagic acid is found in the seeds (88%), while only 12% isfound in the pulp.

24

Ellagitannins are reported to decrease in concentrationduring fruit ripening.

28

Ellagitannins and ellagic acid derivatives have not been identified inblueberries, which is not surprising considering the low concentrations oftotal ellagic acid found in the fruit following acid hydrolysis.

3

Apparently

Vaccinium

sp. lack the genetic capacity to synthesize ellagitannins and ellagicacid derivatives.

3.2.3 Anthocyanins

The major anthocyanidins that may be found in berry fruit differ in thenumber and position of their hydroxyl and methoxyl groups on the B ring(Figure 3.3). Anthocyanidins rarely occur in nature because of their instability.When glycosylated with one or more sugar moieties, they are called antho-cyanins, with single sugars attached at the C3 position of the flavan structure.

Figure 3.3

Structures of (A) the flavonoid skeleton and (B) various flavonols andanthocyanidins.

O

3'

2

345

7

6

84'

5'

2'

6'

O

OOH

OH

OH

OH

R1

R2O

OH

OH

OH

OH

R1

R2

+

Flavonol Anthocyanidin

Flavonol Anthocyanidin R1 R2 Kaempferol Pelargonidin H H Quercetin Cyanidin OH H Myricetin Delphinidin OH OH Isorhamnetin Peonidin OCH3 H Larycitrin Petunidin OCH3 OH Syringetin Malvidin OCH3 OCH3

A.

B.



Glucose, galactose, arabinose, xylose, and rhamnose are the most commonsugars attached to berry anthocyanins. Common diglycosides found in var-ious berry fruit that may be attached at the C3 position of the flavan ring orC5 position of the A ring include rutinose (glucose, rhamnose), sambubiose(glucose, xylose), and sophorose (glucose, glucose). The sugar moieties ofberry anthocyanins can be acylated with aliphatic (acetic, malonic, succinic,oxalic) acids. The variety of glycosidic and aliphatic substitutions leads to awide range of colors in the fruit and can be quite useful in taxonomicclassification and the detection of adulterations in fruit juices.

The anthocyanins in berry fruit have been well characterized byHPLC-MS (Table 3.1). Strawberry anthocyanins are present almost exclusivelyin nonacylated form (99%).

29

Most of the anthocyanins exist as monoglycosides(93%), with the balance (7%) present as diglycosides.

29

The anthocyaninsidentified in strawberries include the 3-glucosides and 3-rutinosides ofcyanidin and perlargonidin, and two acylated derivatives of pelargonidin,3-(malonyl) glucoside and 3-(6-acetyl)-glucoside,

30

as well as a minor peaktentatively identified as pelargonidin 3-diglucoside.

8

Previously Wang et al.

9

identified two additional acylated compounds, cyanidin 3-(succinoyl)glucoside and pelargonidin 3-(succinoyl)glucoside. Strawberries are alsoreported to contain small quantities of four flavonol-anthocyanin complexescomprised of pelargonidin 3-glucoside connected to catechin, epicatechin,afzelechin, and epiafzelechin via

α

4

→

8 linkages.

31

The novel aglycone5-carboxypyranopelargonidin has also been isolated in small amounts fromthe fruit.

32

Pelargonidin 3-glucoside is the predominant anthocyanin instrawberries, accounting for more than 70% of total anthocyanins,

9,11,33

andis largely responsible for the red color of the fruit. The strawberry fleshcontains higher levels of pelargonidin 3-glucoside and pelargonidin 3-rutinosidethan the achenes, while the achenes contain higher levels of cyanidin 3-glucosideand cyanidin 3-(malonyl) glucoside.11

Cyanidin derivatives predominate in blackberries with various sugar(glucose, arabinose, rutinose, and xylose) moieties attached at C3. The antho-cyanins are present predominately in nonacylated form (94%).29 The antho-cyanins exist mostly as monoglycosides (90%), with the balance (10%)present as diglycosides.29 Three acylated derivatives—cyanidin 3-(3-malonyl)glucoside, cyanidin 3-(6-malonyl) glucoside, and cyanidin 3-dioxaloylgluco-side—as well as the 3-glucoside of pelargonidin have also been identified inthe fruit.30 Cyanidin 3-dioxaloylglucoside, a novel zwitterion first identifiedin Evergreen blackberry (Rubus laciniatus), appears to be a unique anthocy-anin in blackberry fruit.34 Several studies have reported the anthocyanindistribution in blackberry genotypes.35,36 The distribution of anthocyanins in51 blackberry samples ranged from 44% to 95% for cyanidin 3-glucoside,trace to 53% for cyanidin 3-rutinoside, not detected to 11% for cyanidin3-xyloside, trace to 5% for cyanidin 3-(malonyl) glucoside, and not detectedto 15% for cyanidin 3-dioxaloylglucoside.35 In the study by Cho et al.,36 theanthocyanin distribution in six blackberry genotypes ranged from 75% to84% for cyanidin 3-glucoside, 1% to 12% for cyanidin 3-rutinoside, 4% to 8%


Chapter 3: Berry fruit phytochemicals 81Ta

ble

3.1

Com

posi

tion

and

Mas

s Sp

ectr

al D

ata

of A

ntho

cyan

in G

lyco

sid

es in

Com

mon

Ber

ry F

ruit

m/z

Ref

eren

ce

Bla

ck r

aspb

erry

[M+

]Fr

agm

ents

2930

Cya

nid

in 3

-sam

bubi

osid

e58

128

7√

√C

yani

din

3-g

luco

sid

e44

928

7√

√C

yani

din

3-x

ylos

ylru

tino

sid

e72

758

1/28

7√

Cya

nid

in 3

-sam

bubi

osid

e-5-

rham

nosi

de

727

581/

433/

287

√C

yani

din

3-r

utin

osid

e59

544

9/28

7√

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larg

onid

in 3

-glu

cosi

de

433

271

√Pe

larg

onid

in 3

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inos

ide

579

433/

271

√√

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idin

3-r

utin

osid

e60

946

3/30

1√

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ckbe

rry

2931

2632

33C

yani

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928

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alon

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gluc

osid

e53

528

7√

√√

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Peon

idin

3-g

luco

sid

e46

330

1√

Cya

nid

in 3

-xyl

osid

e41

928

7√

√√

√√

Cya

nid

in 3

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mal

onyl

) gl

ucos

ide

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449/

287

√C

yani

din

3-d

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loyl

gluc

osid

e59

328

7√

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Red

ras

pber

ry15

2916

19C

yani

din

3,5

-dig

luco

sid

e61

144

9/28

7√

√C

yani

din

3-s

opho

rosi

de

611

287

√√

√√

Cya

nid

in 3

-(2,

6-gl

ucos

ylru

tino

sid

e)75

761

1/28

7√

√√

Cya

nid

in 3

-glu

cosi

de

449

287

√√

√√

Cya

nid

in 3

-sam

bubi

osid

e58

144

9/28

7√

(con

tinu

ed)


82 Berry fruit: Value-added products for health promotionTa

ble

3.1

Com

posi

tion

and

Mas

s Sp

ectr

al D

ata

of A

ntho

cyan

in G

lyco

sid

es in

Com

mon

Ber

ry F

ruit

(C

onti

nued

)

m/z

Ref

eren

ce

Pela

rgon

idin

3-s

opho

rosi

de

595

324/

271

√√

Cya

nid

in 3

-xyl

osyl

ruti

nosi

de

727

581/

287

√√

Cya

nid

in 3

-rut

inos

ide

595

287

√√

√√

Pela

rgon

idin

3-(

2,6-

gluc

osyl

ruti

nosi

de)

741

595/

271

√Pe

larg

onid

in 3

-glu

cosi

de

433

271

√√

√√

Pela

rgon

idin

3-r

utin

osid

e57

927

1√

√√

Cya

nid

in 3

-sop

horo

sid

e-5-

rham

nosi

de

757

611/

433/

287

√C

yani

din

3-s

ambu

bios

ide-

5-rh

amno

sid

e72

758

1/43

3/28

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wbe

rry

911

2934

198

Cya

nid

in 3

-glu

cosi

de

449

287

√√

√√

√√

Cya

nid

in 3

-rut

inos

ide

595

449/

287

√Pe

larg

onid

in 3

-glu

cosi

de

433

271

√√

√√

√√

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rgon

idin

3-r

utin

osid

e57

943

3/27

1√

√√

√√

√Pe

larg

onid

in 3

-(m

alon

yl)g

luco

sid

e51

943

3/27

1√

√√

Pela

rgon

idin

3-(

6”-a

cety

l)gl

ucos

ide

475

271

√Pe

larg

onid

in 3

-(su

ccin

yl)g

luco

sid

e53

327

1√

√C

yani

din

3-(

succ

inyl

)glu

cosi

de

**

√√

Pela

rgon

idin

3-d

iglu

cosi

de

545

433/

271

√

Blu

eber

ry[M

+]

Frag

men

ts29

3536

3337

3839

13D

elph

inid

in 3

-gal

acto

sid

e46

530

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√D

elph

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in 3

-glu

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de

465

303

√√

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√√

Cya

nid

in 3

-gal

acto

sid

e44

928

7√

√√

√√

√√

√D

elph

inid

in 3

-ara

bino

sid

e43

530

3√

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√√

√√

√C

yani

din

3-g

luco

sid

e44

928

7√

√√

√√

√√

√Pe

tuni

din

3-g

alac

tosi

de

479

317

√√

√√

√√

√√


Chapter 3: Berry fruit phytochemicals 83C

yani

din

3-a

rabi

nosi

de

419

287

√√

√√

√√

Petu

nid

in 3

-glu

cosi

de

479

317

√√

√√

√√

√√

Peon

idin

3-g

alac

tosi

de

463

301

√√

√√

√√

√Pe

tuni

din

3-a

rabi

nosi

de

449

317

√√

√√

√√

√√

Peon

idin

3-g

luco

sid

e46

330

1√

√√

√M

alvi

din

3-g

alac

tosi

de

493

331

√√

√√

√√

√√

Mal

vid

in 3

-glu

cosi

de

493

331

√√

√√

√√

√√

Mal

vid

in 3

-ara

bino

sid

e46

333

1√

√√

√√

√√

√C

yani

din

3-(

mal

onyl

)glu

cosi

de

535

287

√C

yani

din

3-(

6”-a

cety

l)ga

lact

osid

e49

128

7√

√√

Mal

vid

in a

cety

l hex

osid

e53

533

1√

Petu

nid

in P

ento

sid

e44

931

7√

Del

phin

idin

3-(

mal

onyl

)glu

cosi

de

551

303

√M

alvi

din

3-(

mal

onyl

)glu

cosi

de

579

331

√D

elph

inid

in 3

-(6”

-ace

tyl)

gluc

osid

e50

730

3√

√√

√√

Peon

idin

3-(

6”-a

cety

l)ga

lact

osid

e50

530

1√

√√

Cya

nid

in 3

-(6”

-ace

tyl)

gluc

osid

e49

128

7√

√√

√M

alvi

din

3-(

6”-a

cety

l)ga

lact

osid

e53

533

1√

√√

√Pe

tuni

din

3-(

6”-a

cety

l)gl

ucos

ide

521

317

√√

√√

√Pe

onid

in 3

-(6”

-ace

tyl)

gluc

osid

e50

530

1√

√√

√M

alvi

din

3-(

6”-a

cety

l)gl

ucos

ide

535

331

√√

√√

√√

Cya

nid

in 3

-(ac

etyl

)ara

bino

sid

e*

*√

√Pe

tuni

din

3-(

acet

yl)g

alac

tosi

de

**

√√

Peon

idin

3-a

rabi

nosi

de

433

301

√√

Del

phin

idin

3-(

acet

yl)g

alac

tosi

de

**

√

* N

o m

ass

spec

tral

dat

a re

port

ed.



for cyanidin 3-xyloside, 2% to 3% for cyanidin 3-(malonyl) glucoside, and3% to 8% for cyanidin 3-dioxaloylglucoside. The effect of genetics on antho-cyanin composition was also observed in a study by Reyes-Carmona et al.37

They found that a wild cultivar contained a larger peak of cyanidin 3-rutinoside,but a lower peak of cyanidin 3-glucoside than the cultivar Comanche. Theyalso found that Marion and Evergreen berries had lower peaks of cyanidinglycosides, but contained a peak identified as malvidin 3-glucoside that wasnot present in the wild and Comanche cultivars.

Similar to blackberries, cyanidin derivatives also predominate in red andblack raspberries,15,19,38 but their profiles are quite distinct due to genetic dif-ferences. The anthocyanins in black and red raspberries are present exclusivelyin nonacylated form.29 In terms of the degree of glycosylation, the percentagesof mono-, di-, and triglycosides in black and red raspberries are reported as13%, 64%, and 23%, and 22%, 52%, and 26%, respectively.29 The seven antho-cyanins identified in red raspberries include cyanidin 3-sophoroside, cyanidin3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-glucoside, pelargonidin3-rutinoside, cyanidin 3-sophoroside-5-rhamnoside, and cyanidin 3-sambubi-oside-5-rhamnoside.30 Black raspberries contain all of the anthocyanins foundin red raspberries, with the exception that they lack cyanidin 3-sophoroside,but contain cyanidin 3-sambubioside and peonidin 3-rutinoside.30 Raspberriesare unique in that both red and black fruit contain the trisaccharide cyanidin3-sambubioside-5-rhamnoside, while cyanidin 3-sophoroside-5-rhamnoside ispresent only in red fruit.30 Cyanidin 3-sophoroside is the major anthocyaninfound in red raspberries, followed by cyanidin 3-sophoroside-5-rhamnosideand cyanidin 3-glucoside, while cyanidin 3-rutinoside is the predominantanthocyanin found in black raspberries, followed by cyanidin 3-sambubio-side-5-rhamnoside and cyanidin 3-glucoside.

Blueberries are a unique berry fruit in that they contain the monoglyco-sides (glucosides, galactosides, and arabinosides) of delphinidin, cyanidin,petunidin, peonidin, and malvidin. Due to the diversity in monoglycosidesand acylation with aliphatic acids such as acetic and malonic, more than 25anthocyanins have been identified in blueberries.30,39,40 The anthocyanin com-position and content of blueberries is influenced by genetics. According toCho et al.,36 the percentage distribution of monomeric anthocyanins in fiveblueberry genotypes was delphinidin (27% to 40%), malvidin (22% to 33%),petunidin (19% to 26%), cyanidin (6% to 14%), and peonidin (1% to 5%),while the distribution of acylated anthocyanins ranged from nondetectableto 9%. In terms of the percent distribution of anthocyanin glycosides, galac-tosides accounted for 60% to 67%, arabinosides 26% to 32%, and glucosides2% to 29%. Interestingly, four Southern highbush genotypes contained highlevels of galactosides and arabinosides, and low levels of glucosides, whileBluecrop, a northern highbush genotype, contained similar levels of the threeglycosides, indicating that synthesis of transferases involved in the attach-ment of specific sugar moieties is genetically coordinated. The effect ofgenetics on the composition of acylated anthocyanins was reported by Gaoand Mazza.39 They found that 7 of 10 lowbush blueberry genotypes did not



vary significantly in anthocyanin composition, but three genotypes had prac-tically no acylated anthocyanins, suggesting that the synthesis of transferasesinvolved in the attachment of acyl groups is also under genetic control. Thepercent distribution of anthocyanidins was shown to vary among commer-cially important blueberry species, with cyanidin, delphinidin, malvidin,peonidin, and petunidin accounting for 31%, 43%, 5%, 7%, and 14% of totalanthocyanins in bilberry, 14%, 38%, 24%, 7%, and 16% in lowbush blueberry,and 6%, 41%, 32%, 1%, and 19% in highbush blueberry, respectively.40 Theanthocyanins in blueberries are present predominantly in the skin, with theexception of bilberry, in which they reside in both the skin and flesh.

3.2.4 Flavonols

The flavonols have a double bond between C2 and C3, a hydroxyl group atC3, and a ketone group at the C4 position of the C ring of the flavan nucleus(Figure 3.3). The most common flavonols in berry fruit—quercetin, myricetin,and kaempferol—differ in the number and position (C3 and C5) of OH groupson the B ring. Flavonols in plants commonly occur as O-glycosides withsugars attached at the C3 position. Glucose and galactose are the most com-mon sugars attached, but rutinose, xylose, arabinose, and rhamnose may alsobe found. Similar to anthocyanins, sugar moieties of berry flavonols can beacylated with various acids (acetic, glutaric, glucuronic, oxalic, and caffeic).

Many flavonols present in common berry fruit have been identified byHPLC-MS (Table 3.2). The glucuronides and glucosides of quercetin andkaempferol, as well as dihydroflavonol, quercetin rutinoside, and kaempferolcoumaroylglucoside have been identified in strawberries. Quercetin 3-glucosideand quercetin 3-glucuronide are the major flavonols in the fruit, although onestudy indicates that quercetin 3-rutinoside is also a major compound.8 Theflavonols in strawberries are concentrated in the achenes, which containfour–fold higher levels than the flesh.11 Four quercetin derivatives (rutino-side, glucoside, glucuronide, methylquercetin-pentose) and kaempferol glu-curonide have been identified in red raspberries, and similar to strawberries,quercetin 3-glucoside and quercetin 3-glucuronide are the major flavonolsin the fruit.15,17,19 The flavonol composition of blackberries is more complex,with nine quercetin and three kaempferol derivatives identified, includingtwo acylated compounds—quercetin 3-[6-(3-hydroxy-3-methylglutaroyl)]-β-galactoside and quercetin 3-oxalylpentoside. In a study involving five gen-otypes, quercetin 3-galactoside and quercetin 3-glucoside were found to bethe major flavonols in the fruit, with two genotypes having appreciable levelsof quercetin 3-[6-(3-hydroxy-3-methylglutaroyl)]-β-galactoside.41 Kaempferolderivatives have been identified in several studies,26,42 but not in others,36,41

suggesting that the ability of fruit to synthesize kaempferol is influenced bygenetics. Flavonols are located exclusively in the fleshy part of the drupelet.26

Blueberries are unique compared to other berry fruit in that they contain alarge number of flavonols. Fourteen quercetin derivatives, including severalcompounds acylated with caffeic and acetic acids, three myricetin derivatives,



Table 3.2 Composition and Mass Spectral Data of Flavonol Glycosides in Common Berry Fruit

m/z Reference

Red raspberry [M−] Fragments 15 19 17Quercetin 3-rutinoside 609 301 √ √Quercetin 3-glucoside 463 301 √ √ √Quercetin 3-glucuronide 477 301 √ √ √Methylquercetin-pentose conjugate 447 301 √Kaempferol glucuronide 461 285 √Quercetin 3,4’-diglucoside 625 463/301 √Quercetin-galactosylrhamnoside 609 301 √

Strawberry 19 34 9 8Quercetin 3-glucuronide 477 301 √ √ √ √Kaempferol 3-glucuronide 461 285 √ √ √ √Quercetin 3-glucoside 463 301 √ √ √Kaempferol 3-glucoside * * √ √Dihydroflavonol ** ** √ √Kaempferol 3-rutinoside 609 301 √Quercetin 3-rutinoside 593 285 √

Blackberry 33 45 26 46 47Quercetin 3-galactoside 463 301 √ √ √ √Quercetin 3-glucoside 463 301 √ √ √ √Quercetin 3-rutinoside 609 463/301 √ √ √ √Quercetin 3-xylosylglucuronide 607 301 √ √Quercetin 3-glucosylpentoside 595 433/301 √ √Kaempferol 3-glucuronide * * √Kaempferol 3-glucoside * * √ √Kaempferol 3-galactoside * * √Kaempferol 3-xylosylglucuronide * * √Quercetin 3-glucuronide 477 301 √Quercetin 3-O-[6-(3-hydroxy-3- methyl-glutaroyl)-B-D-galactoside

607 463/301 √ √

Quercetin 3-methoxyhexoside 493 463/301 √Quercetin 3-oxalylpentoside 505 433/301 √

Blueberry 33 48 47 37Myricetin 3-arabinoside * * √Myricetin 3-hexoside 479 317 √ √Myricetin 3-rhamnoside 463 317 √ √Quercetin 3-galactoside 463 301 √ √ √ √Quercetin 3-glucoside 463 301 √ √ √ √Quercetin 3-rutinoside 609 463/301 √ √Quercetin 3-pentoside 433 301 √ √ √Quercetin 3-acetylrhamnoside 489 447/301 √

(continued)



and kaempferol 3-glucoside, have been identified in the fruit. Quercetin3-galactoside is the predominant flavonol in the fruit, but several genotypescontain appreciable levels of quercetin 3-rhamnoside.41 Blueberry flavonolsare located predominantly in the skin, with small amounts found in the seedsand none detected in the flesh.43

3.2.5 Proanthocyanidins

Proanthocyanidins, also known as condensed tannins, are comprised of oli-gomeric and polymeric flavan-3-ols (Figure 3.4). Linkage of the flavan-3-olunits occurs mainly through the C4→C8 bond, although a C4→C6 bond mayalso exist (B-type linkages). The proanthocyanidins are classified accordingto the type of flavan-3-ols present, which vary in their OH patterns at C3 onthe B ring. The two major classes of proanthocyanidins found in berry fruitinclude procyanidins, composed exclusively of epi(catechin) units, and pro-pelargonidins, composed exclusively of (epi)afzelechin units.

Berry fruits vary markedly in proanthocyanidin composition and con-tent. Blueberry and blackberry procyanidins consist exclusively of (epi)cat-echin units (procyanidins), whereas strawberry and raspberry procyanidinsare comprised of both (epi)catechin and (epi)afzelechin (propelargonidin)units.44 The total proanthocyanidin content of highbush blueberries, lowbushblueberries, blackberries, Marion berries, raspberries, and strawberries is180, 332, 27, 9, 30, and 145 mg/100 g FW.45 Polymeric flavan-3-ols (degreeof polymerization greater than 10) are the predominant proanthocyanidinsin blueberries and strawberries, while blackberries and raspberries containnondetectable to trace levels of polymers.45 The polymeric procyanidins fromlowbush blueberries were characterized by Gu et al.46 and are reported torange in degree of polymerization from 20 to 114, with epicatechin accounting

Table 3.2 (Continued) Composition and Mass Spectral Data of Flavonol Glycosides in Common Berry Fruit

m/z Reference

[M] Fragments 15 19 17Quercetin 3-rhamnoside 447 301 √ √ √Quercetin 3-methoxyhexoside 493 463/301 √Quercetin 3-glucuronide 477 301 √Quercetin 3-glucosylpentoside 595 433/301 √Quercetin 3-caffeoylgalactoside 623 463/301 √Quercetin 3-caffeoylglucoside 623 463/301 √Quercetin 3-oxalylpentoside 505 433/301 √Quercetin 3-acetylgalactoside 505 463/301 √Quercetin 3-acetylglucoside 505 463/301 √Kaempferol 3-glucoside * * √

* No mass spectral data reported.** Unknown compound.



for 100% of extension units, and catechin and epicatechin accounting for 67%and 33%, respectively, of terminal units. Catechin is the major flavan-3-ol instrawberries, ranging in concentration from 2 to 9 mg/100 g FW,11,19,47 and isuniformly distributed in the flesh and achenes.11 Epicatechin is the predominantflavan-3-ol in red raspberries, ranging in concentration from 2 to 5 mg/100 gFW,19,47 while yellow fruit contain low levels (less than 1 mg/100 g FW) ofboth catechin and epicatechin.19 Blackberries contain much higher levels ofepicatechin than catechin, with catechin less than 1 mg/100 g FW and epicat-echin 1 to 18 mg/100 g FW.26,47 The flavan-3-ols are located predominantlyin seeds, which contain four–fold higher levels of epicatechin than wholefruit.26 Epicatechin is the major flavan-3-ol in blueberries, present at a concen-tration of 1 mg/100 g FW.47

Figure 3.4 Structures of various monomeric and dimeric procyanidins.



3.3 Phenolic content of berry fruitThe wide range of values reported for various classes of phenolics in berries(Table 3.3 and Table 3.4) reflect differences in genetics, cultural practices,environmental growing conditions, and possibly maturation. In addition,the values are affected by differences in extraction conditions, analyticalprocedures, and standards used for quantification, making comparisonsamong studies difficult.

The common method for determining the amount of total phenolics inberries is based on the Folin Ciocalteu (FC) reagent,48 with the total amountof phenolics expressed as gallic acid equivalents. Although the method hasseveral limitations, such as differential responses of various groups ofphenolics to the FC reagent and interference from nonphenolic compoundswith reducing capacity, it is a simple assay to perform and has been widelyused.

3.3.1 Raspberry

The levels of total phenolics over all studies range from 428 to 1079 mg/100 gFW for black fruit, 192 to 512 mg/100 g FW for red fruit, 428 to 451 mg/100 gFW for pink/red fruit, and 241 to 359 mg/100 g FW for yellow fruit.Anthocyanins are the major phenolics present in black raspberries, withlevels ranging from 464 to 627 mg/100 g FW. Black raspberries also containappreciable levels of total ellagic acid,49 which most likely is due to highconcentrations of ellagitannins in the fruit (Howard, L.R. and Hager, T.J.,unpublished data). Red raspberries contain much lower levels of anthocya-nins than black raspberries, with values ranging from 19 to 89 mg/100 gFW. Ellagitannins appear to be the major phenolics in both red and yellowraspberries, with the total ellagic acid content ranging from 38 to 270 mg/100 g FW in red fruit and 58 to 194 FW mg/100 g in yellow fruit. Red andblack raspberry seeds are a rich source of ellagitannins, containing 870 and670 mg/100 g seeds of total ellagic acid, respectively.50 Red raspberries alsocontain appreciable levels of total procyanidins (30 mg/100 g FW).45 Fla-vonols are minor phenolic constituents in raspberries regardless of color,with values ranging from less than 1 to 19 mg/100 g FW. Consistent withthe data summarized in Table 3.3, Kahkonen et al.51 measured the amountsof different phenolic classes in red raspberries with data expressed on a dryweight (DW) basis and reported that ellagitannins (1717 mg/100 g DW) andanthocyanins (230 mg/100 g DW) were the predominant phenolics, withmuch lower levels of flavonols (23 mg/100 g DW), hydroxycinnamic acids(25 mg/100 g DW), and hydroxybenozoic acids (24 mg/100 g DW) presentin the fruit. Viljanen et al.52 also reported that ellagitannins and anthocyaninswere the major phenolics in red raspberries, accounting for 51% and 31%,respectively, of total phenolics determined by HPLC. Procyanidins and freeellagic acid accounted for 8% and 9%, respectively, of total phenolics, whileflavonols accounted for less than 1%.



Table 3.3 Total Contents (mg/100 g FW) of Phenolics, Anthocyanins, Flavonols, and Ellagic Acid in Common Berry Fruit

Total phenolicsa

Total anthocyanins

Total flavonols

Total ellagic acidb

Numberof

genotypes Color Reference

Raspberry241–265 ND <1c 58 3 Yellow 85NA ND <1d 194 1 Yellow 19359 <1e NA NA 1 Yellow 86428–451 3–5e NA NA 2 Pink/Red 86192–359 19–51f <1–2c 38–118 12 Red 85211 39f NA NA 1 Red 69513 58e NA NA 1 Red 86NA 73–89f <1d 186–270 3 Red 19517 65f 11d 47 1 Red 49237–512 NA NA NA 12 Red 87890–1079 464–627f NA NA 3 Black 54980 589f 19d 90 1 Black 49StrawberryNA 6–45g <1–4h <1–1 20 5NA 31–37f 2–3d 65–84 3 19NA NA <1–1h 40–59 9 2NA 48–102f 1–5i 2–5 14 9NA NA NA 2–5 5 2343–94 19–84f 1–5j 1–3 18 67202–273 22–47f NA NA 8 88Blackberry822–844 154–225f 12–18d 2–4 2 26248–633 NA NA NA 12 89NA 58–219e NA NA 12 90NA 70–201f NA NA 51 35682–1056 131–256f 4–9d 8–28 11 28193–352 67–127f NA NA 7 91114–178 31–118f NA 21–24 4 92418–555 111–123f ND–10h 30–34 2 55275–650 80–230f NA NA 27 56NA 114–242f 10–16d NA 6 36292–446 NA 10–15d NA 6 41495–583 91–155f 11–30d 59–90 2 49

NA, not available; ND, not detected.a Calculated as gallic acid equivalents.b Calculated as ellagic acid equivalents following acid hydrolysis.c Calculated as quercetin following acid hydrolysis.d Calculated as rutin equivalents.e Calculated as cyanidin 3-galactoside equivalents.f Calculated as cyanidin 3-glucoside equivalents.g Cyanidin and pelargonidin glycosides calculated as cyanidin 3-glucoside and pelargonidin

3-glucoside equivalents, respectively.h Calculated as kaempferol, quercetin, and myricetin following acid hydrolysis.i Calculated as quercetin 3-glucoside equivalents.j Calculated as quercetin 3-galactoside equivalents.



3.3.2 Strawberry

The levels of total phenolics over all studies range from 43 to 273 mg/100 gFW. The wide ranges in total anthocyanins (6 to 102 mg/100 g FW) and totalellagic acid (less than 1 to 84 mg/100 g FW) reported in the literature indicatethat anthocyanins and ellagitannins are major phenolics in the fruit, but itis unclear which class of phenolics predominates. The wide discrepancies intotal ellagic acid values may be explained by differences in acid hydrolysis

Table 3.4 Total Contents (mg/100 g FW) of Phenolics, Anthocyanins, Flavonols, and Chlorogenic Acid in Blueberries

TypeTotal

phenolicsa

Total anthocyanins

Total flavonols

Chlorogenic acidb

Number ofgenotypes Reference

Highbush 111–325 20–184c NA NA 62 62Highbush 227 NA 23d NA 1 41Highbush NA 144e 26d 42 1 36Highbush NA 111c NA 99 1 39Highbush 318 77c NA NA 1 63Highbush 181–391 93–235c NA NA 8 56Highbush NA 100c 40d 27 1 13Highbush 106–120 74–88c 9–10f 98–158 3 14Highbush 412 120c 34f 65 1 70Highbush 249–435 84–269c NA NA 5 54Lowbush NA 120–260c NA 59–110 10 39Lowbush 295–495 91–192c NA NA 6 56Rabbiteye 231–458 62–187c NA NA 6 56Rabbiteye 270–930 13–197c 3–17f NA 12 55Rabbiteye 717–961 242–515c NA NA 4 54Southern

highbushNA 144–823e 17–33f 36–108 4 36

Southern highbush

254–370 NA 19–32f NA 4 41

Southern highbush

116–225 47–160c NA NA 18 62

Southern highbush

202–586 50–249c NA NA 17 63

Southern highbush

227–473 62–157c NA NA 6 56

Southern highbush

262–585 35–130c 13–24f NA 5 55

Southern highbush

171–369 73–119c NA NA 3 54

a Calculated as gallic acid equivalents.b Calculated using authentic standard.c Calculated as cyanidin 3-glucoside equivalents.d Calculated as rutin equivalents.e Delphinidin, cyanidin, petunidin, peonidin, and malvidin glycosides calculated as del-

phinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, peonidin 3-glucoside,and malvidin 3-glucoside equivalents, respectively.

f Calculated as kaempferol, quercetin, and myricetin following acid hydrolysis.



conditions and analytical techniques used to measure and quantify thediverse ellagic acid derivatives in the fruit. The high values (65 to 84 mg/100 g FW) reported by Maata-Riihinen et al.19 reflect a comprehensive HPLCanalysis of free and conjugated forms of ellagic acid, as well as soluble andinsoluble ellagitannins. In addition to anthocyanins and ellagitannins, straw-berries are rich in total procyanidins (145 mg/100 g FW).45 Similar to rasp-berries, flavonols are minor phenolics in the fruit, with values ranging fromless than 1 to 5 mg/100 g FW. Kahkonen et al.51 measured the amounts ofdifferent phenolic classes in strawberries with data expressed on a dryweight basis and reported that anthocyanins (204 mg/100 g DW) and ella-gitannins (127 mg/100 g DW) were the predominant phenolics in the fruit,with much lower levels of hydroxycinnamic acids (56 mg/100 g DW),hydroxybenzoic acids (28 mg/100 g DW), and flavonols (12 mg/100 g DW)present in the fruit.

3.3.3 Blackberry

The levels of total phenolics over all studies range from 114 to 1056 mg/100 gFW. Anthocyanins are the major phenolics in the fruit, with concentrationsranging from 31 to 256 mg/100 g FW. Compared to anthocyanins, blackber-ries contain much lower levels of total procyanidins (9 to 27 mg/100 g FW),46

flavonols (4 to 30 mg/100 g FW), ellagic acid (2 to 34 mg/100 g FW), andphenolic acids (7 to 64 mg/100 g FW).12,53 Marion and Evergreen blackberryseeds appear to be exceptionally rich in ellagitannins, containing 3230 and2120 mg/100 g seed of total ellagic acid, respectively.50

3.3.4 Blueberry

The levels of total phenolics in highbush, lowbush, rabbiteye, and southernhighbush blueberries over all studies range from 106 to 435 mg/100 g FW,295 to 495 mg/100 g FW, 231 to 961 mg/100 g FW, and 116 to 586 mg/100 gFW, respectively. Blueberries are particularly rich in anthocyanins, procya-nidins, and the hydroxycinnamate chlorogenic acid. Total anthocyanin levelsin highbush, lowbush, rabbiteye, and southern highbush blueberries overall studies range from 20 to 269 mg/100 g FW, 91 to 260 mg/100 g FW, 13to 515 mg/100 g FW, and 35 to 823 mg/100 g FW, respectively. Highbushand lowbush blueberries contain 180 and 332 mg/100 g FW of total procy-anidins, respectively.46 The chlorogenic acid content of highbush, lowbush,and southern highbush berries over all studies ranges from 27 to 158 mg/100 g FW. Blueberries contain higher levels of flavonols than raspberries andstrawberries, but have similar levels as blackberries, with concentrationsranging from 9 to 33 mg/100 g FW. In contrast to raspberries, strawberries,and blackberries, blueberries do not contain ellagitannins, and hence containvery low levels of total ellagic acid (less than 5 mg/100 g FW).3

In comparing different blueberry types, several studies indicate thatrabbiteye berries have higher levels of total phenolics and anthocyanins than



southern highbush berries.54,55 In a study by Prior et al.,56 the mean totalphenolics values of lowbush (n = 7), rabbiteye (n = 6), southern highbush(n = 6), and highbush (n = 8) blueberries were 381, 340, 327, and 261 mg/100 gFW, respectively. In the same study, the mean total anthocyanin values oflowbush (n = 7), rabbiteye (n = 6), southern highbush (n = 6), and highbush(n = 8) blueberries were 139, 124, 119, and 129 mg/100 g FW, respectively.According to the study, lowbush blueberries have higher levels of totalphenolics and anthocyanins than rabbiteye, southern highbush, and high-bush blueberries.

3.3.5 Antioxidant capacity of berry fruit

Oxidative stress characterized by an imbalance between the generation ofreactive oxygen species and the activity of antioxidant defense systems inthe body is thought to play a role in the development of a number ofdegenerative diseases.57,58 Although oxidative stress does not appear to bethe primary cause of some of these diseases, excessive radicals formed as asecondary effect of tissue damage may exacerbate chronic diseases. Becauseof the deleterious effects of free radicals in human biology, much attentionhas focused on the role of antioxidant vitamins and phytochemicals in dis-ease prevention. A major thrust of this research has involved screening avariety of foods for antioxidant capacity, and berry fruit have received muchattention because of their high flavonoid content.

The oxygen radical absorbing capacity (ORAC) assay has been themethod of choice to measure the antioxidant capacity of berry extracts. Themethod measures antioxidant scavenging activity against peroxyl radical(ROO.) initiated by 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH).59

B-phycoerythrin (B-PE), a water soluble protein, was initially used as afluorescent probe. The loss of fluorescence measured over time reflects theextent of damage to B-PE by the peroxyl radical. The antioxidant activity isdetermined by measuring the area under the fluorescence decay curve ofthe antioxidant-containing sample compared to that of a blank, which con-tains no antioxidant. Trolox, a water soluble tocopherol analog, is used as astandard, with results typically expressed as micromoles of trolox equiva-lents per gram fresh weight. B-PE has largely been replaced by fluorescein(FL). Compared to B-PE, fluorescein shows greater lot-to-lot consistency, ismore photostable, and does not bind with polyphenols.60 Use of fluoresceinas the probe typically results in 1.5 to 3.5-fold higher ORAC values comparedto B-PE.60 To avoid confusion, the type of probe used should be specifiedwhen reporting ORAC data (e.g., ORACPE or ORACFL).

The hydrophilic ORACPE and ORACFL data for common berry fruit areshown in Table 3.5. The strawberry ORACPE values (n = 14) range from 11.1to 17.8 µmol TE/g FW.9 The ORACPE values for black raspberries range from28.2 to 146.0 µmol TE/g FW. The high values of 100.3 to 146.0 µmol TE/gFW reported by Moyer et al.54 and 77.2 µmol TE/g FW reported by Wadaand Ou49 indicate that black raspberries contain the highest antioxidant



Table 3.5 ORACPE and ORACFL Values of Common Berry Fruit

Fruit TypeNumber of genotypes

ORACPE (µmol TE/g FW) Reference

Strawberry 14 11–18 9Red Raspberry 1 24 49Red Raspberry 3 16–20 61Black Raspberry 3 100–146 54Black Raspberry 1 77 49Black Raspberry 1 28 61Blackberry 27 27–71 54Blackberry 2 34–36 26Blackberry 11 38–76 28Blackberry 2 28 49Blackberry 3 20–25 61Blueberry Highbush 62 6–31 62Blueberry Highbush 1 24 63Blueberry Highbush 8 17–37 56Blueberry Lowbush 6 26–46 56Blueberry Rabbiteye 1 14 62Blueberry Rabbiteye 6 14–38 56Blueberry Southern

highbush17 5–22 62

Blueberry Southern highbush

17 21–73 63


6 17–42 56

ORACFL (µmol TE/g FW)

Strawberry 8 29–42 65Red Raspberry 6 37–58 65Black Raspberry 1 128 66Blackberry 6 63–83 36Blackberry 6 49–76 41Blackberry 4 43–62 65Blueberry Cultivated 8 50–74 65Blueberry Highbush 1 52 36Blueberry Highbush 1 37 41Blueberry Lowbush 1 92 65Blueberry Southern

highbush4 62–139 36


4 44–78 41

ORACFL (µmol TE/g DW)

Blackberry 11 334–560 37



capacity among common berry fruit. The ORACPE values for red raspberriesover all studies range from 15.9 to 24.0 µmol TE/g FW. The ORACPE valuesfor blackberries over all studies range from 20.3 to 70.6 µmol TE/g FW. Ina comprehensive study involving 27 genotypes of blackberries, ORACPE

values ranged from 100.3 to 146.0 µmol TE/g FW, indicating that amplevariation exists for exploitation by plant breeders.54 The low ORACPE valuesreported by Wang and Lin61 for blackberries, black raspberries, and redraspberries may be attributed to the extraction technique. Their measure-ment included only the juice expressed from the fruit, whereas all otherstudies include whole berries, including seeds. The ORACPE values for southernhighbush (n = 40), highbush (n = 71), rabbiteye (n = 7), and lowbush (n = 6)blueberries over all studies range from 4.6 to 73.0 µmol TE/g FW, 5.5 to37.0 µmol TE/g FW, 13.6 to 37.8 µmol TE/g FW, and 25.9 to 45.9 µmol TE/g FW, respectively. Prior et al.56 reported mean ORACPE values for six gen-otypes of southern highbush (26.6 µmol TE/g FW), eight genotypes of high-bush (24.0 µmol TE/g FW), and six genotypes each of rabbiteye (25.0 µmolTE/g FW) and lowbush (34.6 µmol TE/g FW) blueberries. The ORAC valuesof blueberries are reported to be influenced by fruit size, with smaller fruittypically having higher ORAC values than larger fruit.54,56,62,63,64 This is due tolocalization of anthocyanins and flavonols in the epidermal tissue and smallfruit having more epidermal tissue per unit volume than large fruit.

Wu et al.65 reported lipophilic and hydrophilic ORACFL values of com-mon food in the United States, including strawberries, blackberries, redraspberries, and blueberries. In their study the hydrophilic ORACFL valuesof strawberries (n = 8) ranged from 29.2 to 41.7 µmol TE/g FW, with a meanvalue of 12.5 µmol TE/g FW; hydrophilic ORACFL values of red raspberries(n = 6) ranged from 37.4 to 57.9 µmol TE/g FW, with a mean value of 47.7 µmolTE/g FW; hydrophilic ORACFL values of blackberries (n = 4) ranged from42.7 to 62.2 µmol TE/g FW, with a mean value of 52.5 µmol TE/g FW; andhydrophilic ORACFL values of cultivated blueberries (n = 8) ranged from49.7 to 73.9 µmol TE/g FW, with a mean value of 61.8 µmol TE/g FW. Onesample of lowbush blueberries had a hydrophilic ORACFL value of 92.1 µmolTE/g FW. The lipophilic ORACFL values of common berry fruit were verylow, accounting for less than 3% of the total antioxidant capacity. Blackraspberries have a notably high ORACFL value of 128.4 µmol TE/g FW,66 butunfortunately different genotypes of the fruit have not been screened forORACFL. Cho et al.36,41 reported hydrophilic ORACFL values for six similargenotypes of blackberries and blueberries grown at the same location overtwo seasons. The ORACFL values of blackberry samples harvested in 2004ranged from 62.5 to 82.5 µmol TE/g FW, with a mean value of 74.0 µmolTE/g FW, while the ORACFL values of blackberry samples harvested in 2005ranged from 49.4 to 76.1 µmol TE/g FW, with a mean value of 60.7 µmolTE/g FW. The ORACFL values of southern highbush blueberry samplesharvested in 2004 ranged from 62.2 to 139.4 µmol TE/g FW, with a meanvalue of 95.7 µmol TE/g FW, while the ORACFL values of southern highbushblueberry samples harvested in 2005 ranged from 44.4 to 77.6 µmol TE/g



FW, with a mean value of 64.4 µmol TE/g FW. The ORACFL value of onehighbush sample was 51.8 µmol TE/g FW in 2004 and 36.7 µmol TE/g FWin 2005. The much greater values obtained for blackberries and blueberriesin 2004 compared to 2005 suggest that environmental growing conditionscan markedly influence the synthesis of phenolic compounds responsiblefor antioxidant capacity. In comparing mean values from the studies, itappears that lowbush blueberries have higher antioxidant capacity thanhighbush and southern highbush blueberries, with the exception of severalsmall-fruited, highly pigmented, advanced breeding lines of southern high-bush blueberry that have exceptionally high ORACFL values (77.6 to 139.4µmol TE/g FW).36,41

Seeds of common berry fruit are a rich source of phenolics and antiox-idant capacity, with ORACFL values of 540, 151, 146, and 200 µmol TE/g seedreported for red raspberry, black raspberry, Marion blackberry, and Ever-green blackberry seeds, respectively.50

3.3.6 Relationships between phenolic classes and antioxidant capacity

Linear relationships between total levels of phenolics and anthocyanins andantioxidant capacity measured by several methods (ORACPE and ORACFL,2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) [ABTS], ferric reduc-ing antioxidant power [FRAP], 2,2-diphenyl-1-picrylhydrazyl [DPPH]) haveconsistently been reported in studies involving strawberries,11,61,67,68 blackraspberries,54,61 red raspberries,61 blackberries,54,61 and blueberries54,61,62 dem-onstrating that phenolic compounds are the major hydrophilic antioxidantspresent in the fruit. Most studies involving a large number of genotypesreport a higher correlation between total phenolics and antioxidant capacitythan between total anthocyanins and antioxidant capacity,54,56,62,69 which isnot surprising considering the wide array of phenolics present in the fruit.

3.3.7 Contribution of individual flavonoids to antioxidant capacity

Several studies have reported on the antioxidant capacity of phenolic classesand individual phenolics in berry extracts.9,16,70 In a study involving 14 gen-otypes of strawberries grown under two cultural systems, Wang et al.9 col-lected HPLC fractions from each chromatographic peak and measured theORACPE of each compound. They found that the sum of antioxidant activitiesof the individual phenolics in juices separated by HPLC accounted for 48.2% to73.9% of the ORACPE of directly extracted juices. Phenolic acids (p-coumaroylglucose and ellagic acid) accounted for 12.2% to 12.7%, flavonols 20.0% to26.8%, and anthocyanins 50.4% to 67.9% of the total antioxidant capacity ofjuices obtained from fruit grown under the two cultural systems. Phenoliccompounds showing the greatest contributions to antioxidant capacityincluded pelargonidin 3-glucoside (27.1% to 27.3%), cyanidin 3-glucoside(10.6% to 13.3%), and p-coumaroylglucose (9.6% to 10.5%). Using the same



approach as Wang et al.,9 the contribution of phenolic classes and individualphenolics to ORACPE in blueberries was studied.70 The summed ORACPE

values of individual hydroxycinnamic acids, flavonols, and anthocyaninsaccounted for 79% of the whole-fruit extract ORACPE. Chlorogenic acidaccounted for 21%, flavonols 23%, and anthocyanins 56% of the totalORACPE. Other phenolics besides chlorogenic acid providing significant con-tributions to ORACPE included quercetin 3-galactoside (6.2%), myricetin3-arabinoside (5.4%), delphinidin 3-galactoside (9.2%) and glucoside (6.2%),petunidin 3-galactoside (5.8%), and malvidin 3-galactoside (6.3%). Beek-wilder et al.16 studied the antioxidant compounds in red raspberry fruit byHPLC coupled to an online postcolumn antioxidant detection systememploying the ABTS radical. They detected three distinct regions in thechromatograms where major ABTS radical scavenging activities wereobserved. The first region, consisting of highly polar compounds such asascorbic acid, glutathione, and cysteine, contributed about 20% of the totalantioxidant activity in the extract. The second region, consisting of nineanthocyanins, contributed about 25% to the total antioxidant capacity. Thethird region contained two major ellagitannins—sanguiin H-6 and lamber-tianin C—which contributed 40% and 12%, respectively, of the total anti-oxidant capacity. Several procyanidin and other phenolic compounds con-tributed about 5% of the total antioxidant capacity. Consistent with findingsby Beekwilder et al.,16 ellagitannins isolated from red raspberries were moreeffective than anthocyanins in the inhibition of lipid and protein oxidation.52

Results from these studies show that anthocyanins are the major contributorsto antioxidant capacity in blueberries and strawberries, while ellagitanninsare the major contributors to antioxidant capacity in red raspberries. Unfor-tunately the contribution of individual phenolic compounds to total anti-oxidant capacity in blackberries and black raspberries is unknown.

3.4 Other phytochemicals in common berry fruit3.4.1 Lignans

Lignans found in plant-based foods are thought to play an important rolein the prevention of hormone-associated cancers, osteoporosis, and coronaryheart disease because of their phytoestrogenic properties.71 Lignans arebiphenolic compounds, several of which can be converted by intestinalmicroflora into the mammalian lignans enterolactone and enterodiol.Secoisolariciresinol and matairesinol are the major plant lignans, and theyhave been characterized in many commonly consumed foods.72

Common berry fruit, especially blackberries, appear to be a good sourceof secoisolariciresinol. According to Mazur et al.,73 blackberries, strawberries,red raspberries, and blueberries contain 3.72, 1.50, 0.14, and 0.84 mg/100 gDW of secoisolariciresinol, respectively, while matairesinol is only presentin blackberries and strawberries at very low concentrations (less than0.01 mg/100 g DW).



3.4.2 Sterols

Plant sterols have been shown to be effective in decreasing serum total andlow-density lipoprotein (LDL) cholesterol,74 and may afford protectionagainst various types of cancer.75 Plant sterols are characterized by the num-ber and location of double bonds and methylation at the C4 position on thering system, as well as alkylation and double bonds on the side chain. Plantsterols can occur in many forms—free sterols, esterified steryls (free fattyacids and phenolic esters), and steryl glycosides—that can be esterified toacylated steryl glycosides.74 The most common sterols found in fruits are the4-desmethylsterols sitosterol, campersterol, stigmasterol, and avenasterols.74

Piironen et al.76 measured plant sterols in blueberry (Vaccinium myrtillusL.), red raspberry, and strawberry fruit. They found that sitosterol was thepredominant sterol in the fruit, with blueberries, red raspberries, and straw-berries containing 22.2, 23.3, and 7.3 mg/100 g FW, respectively. Stanols werepresent at low concentrations, with blueberries and red raspberries contain-ing 1.7 and 0.2 mg/100 g FW, while the compound was not detected instrawberries. The total plant sterol content of blueberries, red raspberries,and strawberries was 26.4, 27.4, and 10.0 mg/100 g FW, respectively.

3.4.3 Stilbenes

Stilbenes are a class of polyphenolics that are commonly found in grapes, wine,and peanuts. Resveratrol, the most abundant stilbene found in grapes andwine, has received much attention because of its potential cardioprotective77

and chemopreventive properties.78 The stilbene levels in different species ofVaccinium were reported by Rimando et al.79 Resveratrol was the major stilbenein the berries, ranging in concentration from 0.7 to 588.4 mg/100 g DW, andberries from Canada had much higher levels of resveratrol than berries grownat various locations throughout the United States. Pterostilbene and piceatan-nol were not detected in many of the Vaccinium sp., but rabbiteye berriescontained 9.9 to 52.0 mg/100 g DW of pterostilbene, and highbush berriescontained 18.6 to 42.2 mg/100 g DW of piceatannol.

3.5 ConclusionCommon berry fruit are a rich source of antioxidant phenolics with otherhealth-promoting properties. The major phenolics in berries have been iden-tified and quantified over the past decade with advancements in HPLC andHPLC-MS. Black raspberries are exceptionally rich in cyanidin derivativesand contain high levels of ellagitannins, which are the major phenolics foundin yellow and red raspberries, while strawberries contain high levels ofanthocyanins (predominantly pelargonidin derivatives), ellagitannins, andprocyanidins. Anthocyanins, specifically cyanidin derivatives, are the majorphenolics found in blackberries. Blueberries are rich in anthocyanins (pre-dominantly delphindin and malvidin glycosides) and procyanidins, and areunique in that they contain abundant levels of chlorogenic acid.



Although great progress has been made in characterizing berry pheno-lics, more work is needed to identify and quantify blackberry and blackraspberry ellagitannins, and identify native ester and glycoside forms ofphenolic acids. It would also seem prudent to measure the compounds intheir natural glycosidic state, since the size, solubility, degree, and positionof glycosylation, as well as conjugation with other compounds, can impacttheir bioavailability, absorption, and metabolism in humans. There is also areal need for HPLC-grade analytical standards of ellagitannins and phenolicderivatives to be prepared and available for identification and quantificationpurposes.

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79. Rimando, A.M., Kalt, W., Magee, J.B., Dewey, J., and Ballington, J.R., Resveratrol,pterostilbene, and piceatannol in Vaccinium berries, J. Agric. Food Chem., 52, 4713,2004.

80. Tian, Q., Giusti, M.M., Stoner, G.D., and Schwartz, S.J., Characterization of anew anthocyanin in black raspberries (Rubus occidentalis) by liquid chroma-tography electrospray ionization tandem mass spectrometry, Food Chem., 94,465, 2006.

81. Prior, R.L., Lazarus, S.A., Guohua, C., Muccitelli, H., and Hammerstone, J.F.,Identification of procyanidins and anthocyanins in blueberries and cranber-ries (Vaccinium spp.) using high-performance liquid chromatography/massspectrometry, J. Agric. Food Chem., 49, 1270, 2001.

82. Wang, J., Kalt, W., and Sporns, P., Comparison between HPLC and MAL-DI-TOF MS analysis of anthocyanins in highbush blueberries, J. Agric. FoodChem., 48, 3330, 2000.



83. Wald, B., Galensa, R., Herrmann, K., Grotjahn, L., and Wray, V., Quercetin3-O-[6-(3-hydroxy-3-methylglutaroyl)-beta-galactoside] from blackberries,Phytochemistry, 25, 2904, 1986.

84. Kader, K., Rovel, B., Girardin, M., and Metche, M., Fractionation and identi-fication of the phenolic compounds of highbush blueberries (Vaccinium corym-bosum L.), J. Sci. Food Agric., 55, 35, 1996.

85. Antonnen, M.J. and Karjalainen, R.O., Environmental and genetic variationof phenolic compounds in red raspberry, J. Food. Composit. Anal., 18, 759, 2005.

86. Liu, M., Li, X.Q., Weber, C., Lee, C.Y., Brown, J., and Liu, R.H., Antioxidantand antiproliferative activities of raspberries, J. Agric. Food Chem., 50, 2926,2002.

87. Connor, A.M., Stephens, M.J., Hall, H.K., and Alspach, P.A,, Variation andheritabilities of antioxidant capacity and total phenolic content estimatedfrom a red raspberry factorial experiment, J. Am. Soc. Hort. Sci., 130, 403, 2005.

88. Meyers, K.J., Watkins, C.B., Pritts, M.P., and Liu, R.H., Antioxidant and anti-proliferative activities of strawberries, J. Agric. Food Chem., 51, 6887, 2003.

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90. Connor, A.M., Finn, C.E., McGhie, T.K., and Alspach, P.A., Genetic and envi-ronmental variation in anthocyanins and their relationship to antioxidantactivity in blackberry and hybridberry cultivars, J. Am. Soc. Hort. Sci., 130,680, 2005.

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105

chapter 4

Natural pigments of berries: Functionality and application

M. Monica Giusti and Pu Jing

Contents

4.1 Introduction ................................................................................................1064.2 Anthocyanins and other pigments in berries .......................................106

4.2.1 Anthocyanins in berries ...............................................................1064.2.2 Other pigments in berries............................................................120

4.2.2.1 Chlorophylls ....................................................................1204.2.2.2 Flavonols and flavan-3-ols ............................................1204.2.2.3 Carotenoids......................................................................1224.2.2.4 Betalains ...........................................................................122

4.3 Changes in berry pigments during processing and storage..................................................................................................1224.3.1 Changes during fruit ripening, harvesting,

and storage of fresh fruit .............................................................1224.3.2 Processing and storage of berry products ................................123

4.3.2.1 Juice/Wine processing...................................................1244.3.2.2 Heat treatment ................................................................1244.3.2.3 Fruit preserves and jams/syrups.................................1254.3.2.4 Freezing ............................................................................126

4.4 Health benefits of anthocyanins..............................................................1264.4.1 Antioxidants...................................................................................1264.4.2 Cancer chemoprotective properties ...........................................1274.4.3 Cardiovascular diseases ...............................................................1304.4.4 Other health benefits of anthocyanins.......................................1314.4.5 Bioavailability ................................................................................131



4.5 Health benefits of other pigments in berries ........................................1324.6 Potential application of berry pigments ................................................133

4.6.1 Berry pigment profiles as fingerprints for authenticity ..............................................................................133

4.6.2 Berry pigments as natural colorants and value-added ingredients ......................................................133

References.............................................................................................................135

4.1 Introduction

Berries have numerous qualities that make them appealing to consumers.Among these attributes, color is of great importance because consumers useit to judge the quality of a fruit. Berries have many attractive colors that arevalued by consumers all over the world. This chapter will introduce readersto the different pigments responsible for berry color, their chemistry, theirconcentrations, and the many factors that can affect their presence and con-centration in berries and berry products. There are many factors that canaffect fruit composition, including fruit maturity, varietal differences, loca-tion, growing conditions, weather, and time and temperature of storage. Inthis chapter, we will focus on the effects that harvesting, storage, and pro-cessing conditions can have on pigment composition and concentration forvarious species of berries, in addition to the role that berry pigments mayplay in the health benefits attributed to berries and berry products.

4.2 Anthocyanins and other pigments in berries

4.2.1 Anthocyanins in berries

Most of the wonderful red, purple, blue, and deep—almost black—colors inberries are due to the presence of natural pigments called anthocyanins.Anthocyanins are widely distributed, water soluble plant pigments thatprovide color to a variety of fruits, vegetables, cereal grains, and flowers.These pigments have been the subject of investigation by botanists and plantphysiologists because of their roles as pollination attractants and phytopro-tective agents. Anthocyanins play an important role in plant taxonomy andbiochemical systematics as chemical markers in plants and plant products.

1

They are of increasing interest for geneticists and horticulturalists in the fieldof molecular biology.

2

Growing interest also lies in anthocyanin-producingcell cultures as vehicles of secondary metabolites. Food processors are inter-ested in anthocyanins as natural alternatives to the use of synthetic dyes.Interest in natural plant pigments such as anthocyanins has intensified overthe last decade because of their strong antioxidant capacity and possiblehealth benefits.

The concentrations of anthocyanins reported for berries vary greatlyamong different families and species (Table 4.1). Even within the same species,


Chapter 4: Natural pigments of berries: Functionality and application 107

Tabl

e 4.

1

Ant

hocy

anin

Con

cent

rati

ons

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

Cu

ltiv

arA

nth

ocya

nin

s (m

g/10

0 g

FW)

Ref

eren

ces

Cap

rifo

liace

ae

Sam

bucu

s ni

gra

L.

Eld

erbe

rry

n.s.

332

a,b

;

1374

a,c,

d

3,4

Ela

eoca

rpac

eae

Ari

stot

elia

chi

lens

is

(M

ol.)

Stun

tzM

aque

i/m

acqu

in.

s.13

8

a,e

158

Em

petr

acea

e

Em

petr

um n

igru

m

L.

Bla

ck c

row

berr

yn.

s.40

9

a,b

4

E. n

igru

m

ssp

.

Her

map

hrod

itum

n.s.

768

a,b

4

Eri

cace

ae

Vac

cini

um a

ngus

tifo

lium

A

iton

Low

bush

blu

eber

ry

Blo

mid

in

,

low

bu

sh

f

91

,

95–1

80

g,h

21B

runs

wei

ck20

8

g,h

67C

umbe

rlan

d

103

g,h

;

164

d,g,

h

21, 1

59Fu

ndy

192

g,h

;

234

g,h

21, 1

59

Mic

higa

n lo

wbu

sh

, N70

127,

GR

V.a

, N70

68,

N70

249,

N70

145

128

, 174

, 186

, 202

, 205

,

209

g,h

159

n.s.

170

g,h

;

230

a,i

19, 1

60

Vac

cini

um a

shei

Rea

de

Rab

bite

ye

blue

berr

y/sm

allfl

ower

bl

uebe

rry

Blu

egem

, CV

AC

200

.003

, CV

AC

116

1.00

1,

CV

AC

117

0.00

1

242

, 383

, 484

,

515

g,h

67

Tifb

lue

87–1

54

g,h

;

220

g,h

19, 2

1

Bri

ghtw

ell

, Clim

ax,

Lit

tle

Gia

nt

62–1

62

, 91,

187

g,h

21

Vac

cini

um c

onst

abla

ei

Gra

yM

ount

ain

high

bush

bl

uebe

rry

N84

26

, N84

28,

N87

014

168

, 211

,

290

g,h

159

(

cont

inue

d

)



Tabl

e 4.

1 (C

onti

nued

)

Ant

hocy

anin

Con

cent

rati

ons

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

Cu

ltiv

arA

nth

ocya

nin

s (m

g/10

0 g

FW)

Ref

eren

ces

Vac

cini

um c

orym

bosu

m

L.

Hig

hbus

h bl

uebe

rry

(nor

ther

n hi

gh)

Ain

o14

7

a,b

4B

luec

rop

84

g,h

; 93

g,h

; 120

g,h

;

141

g,i

21, 6

7, 1

59,

160

N70

218

, Bou

nty,

B6,

Nel

son,

B11

, B1-

1, B

10,

N86

161,

Frie

nd

ship

139

, 169

, 181

, 188

, 190

, 22

3, 2

40, 3

75,

383

g,h

159

Duk

e

127

g,h

; 173

g,h

;

274

g,h

21, 6

7, 1

59

G-2

24

,

Bri

gitt

a b

lue

91

,

103

g,h

67

Jers

ey

101–

116

g,h

;

197

g,h

21, 1

59

Cro

atan

, Ran

coca

s,

Ru

bel

118

, 141

,

235

g,h

21

Vac

cini

um c

orym

bosu

m

L.

Hig

hbus

h bl

uebe

rry

(sou

ther

n hi

gh)

Rev

eille

, O'N

eal,

Blu

e ri

dge

, Bla

den

,

Cap

e fe

ar, P

end

er

63

, 93,

110

, 131

,

157

,

157

g,h

21

Sum

mit

, G-3

44, S

umm

it I

I, C

VA

C 2

4.00

1,

CV

AC

105

7.00

1, C

VA

C 4

5.00

1, C

VA

C

25.0

01, C

VA

C 3

5.00

1; C

VA

C 2

3.00

1,

CV

AC

5.0

0

73

, 101

, 119

, 224

, 239

, 27

9, 3

03, 3

04, 3

22,

430

g,h

67

Vac

cini

um c

onst

abla

ei

×

Vac

cini

um a

shei

n.a.

MN

494

,

515

,

676

, Chi

ppew

a, P

atri

ot,

Nor

thsk

y, M

N49

6, N

orth

blue

, MN

455,

M

N61

, MN

497,

R2P

4, P

olar

is, S

t. C

loud

, M

N84

, Blu

etta

, MN

449,

Nor

thco

unty

, N

orth

land

, Blu

egol

d, N

8615

8, M

N45

2,

GR

2

1

,

1

,

1

, 114

, 156

, 158

, 16

2, 1

64, 1

65, 1

76, 1

94,

199,

202

, 202

, 210

, 211

, 21

4, 2

17, 2

40, 2

49, 2

80,

341,

428

g,h

159

Vac

cini

um m

acro

carp

on

Ait

on.

Am

eric

an c

ranb

erry

Ben

Lea

r

25

g,j

;

32

g,h

62, 1

61

Cro

pper

, Pilg

rim

, Ste

vens

, How

es, W

ilcox

, #3

5, F

rank

lin, E

arly

bla

ck,

Cro

wle

y

20

, 21,

23,

24,

24,

29,

54,

63

,

66

g,j

161

n.s.

360

g,h

19



Vac

cini

um m

embr

anac

eum

D

ougl

as e

x To

rr.

Thi

nlea

f hu

ckle

berr

yn.

s.

116–

153

g,h

;

167

g,h

63, 6

7

Vac

cini

um m

yrti

lloid

es

Mic

hx.

Can

adia

n bl

uebe

rry/

velv

et-l

eaf

blue

berr

y

CV

AC

19.

001

298

g,h

67

N69

180

,

N70

239

218

,

259

g,h

159

Vac

cini

um m

yrti

llus

L.

Bilb

erry

/w

hort

lebe

rry

n.s.

300

g,h

; 600

a,c

;

808

a,b

4, 7

, 21

Vac

cini

um o

valif

oliu

m

Sm

.B

lack

huc

kleb

erry

/ov

al-l

eaf

blue

berr

y n.

s.26

6

g,h

67

Vac

cini

um o

xyco

ccus

L.

Smal

l cra

nber

ryn.

s.

78

g,h

;

86

a,b

4, 1

62V

acci

nium

par

vifo

lium

Sm

ith

Red

huc

kleb

erry

n.s.

34g,

h67

Vac

cini

um u

ligin

osum

L.

Bog

blu

eber

ry/

bog

who

rtle

berr

yn.

s.25

6a,i ;

261–

432a,

b4,

163

Vac

cini

um v

itis

-ida

ea L

.L

ingo

nber

ry/

mou

ntai

n cr

anbe

rry/

cow

berr

y

Am

berl

and

45

g,h ;

96g,

h62

, 78

Sann

a an

d S

ussi

49–6

9g33

Sann

a , E

rnte

dan

k, S

carl

ett,

Ern

tese

gen,

K

oral

le, E

urop

ean

red

, Red

pea

rl,

Sple

ndor

, Id

a (8

726-

8), K

oral

le-G

erm

an,

Su

ssi

31, 3

8–57

, 41,

52–

57,

54–8

7, 5

5, 5

5–62

, 56

–60,

63,

64,

92g,

h

78

n.s.

68a,

c7

Gro

ssul

aria

ceae

Rib

es u

va-c

risp

a L

.G

oose

berr

yC

arel

ess,

Dan

’s m

ista

ke, L

anca

shin

e,

Wh

inh

am0,

2, 1

0, 1

0a,c

3

Hin

nonm

aki’s

yel

low

, Hin

non

mak

i’s r

ed0,

24a,

b4

Rib

es g

ross

ular

ia ×

Rib

es

oxya

cant

hoid

esG

oose

berr

y hy

brid

sC

apti

vato

r14

g,h

67

Rib

es n

idig

rola

ria

Bau

erJo

stab

erri

esn.

s.43

–89g,

h67

Rib

es n

igru

m L

.B

lack

cur

rant

Bal

dw

in15

3g,h ;

186g,

h67

, 164

Bel

orus

kaja

sla

dka

ja15

7g,h ;

165g

6, 6

7B

en A

lder

240g ;

562a,

c3,

6 (con

tinu

ed)



ble

4.1

(Con

tinu

ed)

Ant

hocy

anin

Con

cent

rati

ons

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

Cu

ltiv

arA

nth

ocya

nin

s (m

g/10

0 g

FW)

Ref

eren

ces

Ben

Lom

ond

206g,

h ; 26

1g,h ;

574a,

c3,

67,

164

Ben

Nev

is25

2g,h ;

587a,

c3,

67

Oje

byn

165g,

h ; 18

0g ; 23

6a,c ;

301a,

b ; 41

2a,b

4, 6

, 7, 8

, 67

Tsem

a18

0g,h ;

261g,

h67

, 164

Tita

nia

281g,

h ; 36

0a,c

3, 6

7Le

ntja

i, St

ella

II,

Sanj

uta,

Sel

eche

ns k

aja,

V

iuch

iai,

Pile

niai

, Ver

nisa

z, J

onin

iai,

Alm

iai,

Cho

rnij

kenr

avr,

Lai

mia

i

96, 1

65, 1

72, 1

73, 1

88,

205,

221

, 226

, 242

, 253

, 26

7g

6

Silv

ergi

eter

s, T

enah

, Noi

r D

e B

ourg

ogne

, B

urg

a20

2, 2

24, 2

29, 2

81g,

h16

4

Slit

sa, H

ysta

wne

znaj

a, M

inaj

sm

yrio

v, B

en

cona

n, A

laga

n, K

anta

ta, R

isag

er, W

assi

l, K

anta

ta 5

0, P

inot

deb

oir,

Pola

r, B

lack

dow

n, N

eosy

spuj

asta

ja,

Kos

mic

zesk

aja,

Cor

onet

Bos

koop

, N

ikka

la X

I, N

ikka

la X

I, D

osz

sibe

rjoc

zk,

Kir

ovch

anka

Tun

naja

, Will

ough

by,

Stra

ta, C

rusa

der

, Silv

ergi

eter

s, Z

war

te,

Con

sort

128,

156

, 158

, 162

, 169

, 18

0, 1

81, 1

99, 2

07, 2

08,

213,

216

, 220

, 220

, 221

, 23

1, 2

40, 2

57, 2

57, 2

59,

263,

275

, 275

, 298

, 319

, 34

6, 4

11g,

h

67

Ukr

aine

, Ben

Tir

ran

323,

452

a,c

3n.

s.35

0h16

5R

ibes

odo

ratu

m W

end

land

Buf

falo

cur

rant

Cra

ndal

l27

3g,h

67R

ibes

× P

allid

umR

ed c

urra

ntR

ed D

utch

18a,

b ; 21

a,b

4, 8

Whi

te D

utch

0a,b

4R

ibes

rub

rum

L.

Cul

tiva

ted

cur

rant

Ros

etta

, Red

lake

, Rot

et22

, 23,

34g,

h16

4M

yrta

ceae



Eug

enia

um

belli

flora

O. B

erg

Bag

uaçu

n.s.

342a,

k16

6R

osac

eae

Aro

nia

mel

anoc

arpa

(M

ichx

.) E

lliot

Bla

ck c

hoke

berr

yN

ero

461g,

h16

4V

ikin

g 84

2a,b

4A

lbig

owa,

Dab

row

ice,

Ege

rta,

Kut

no,

Ner

o, N

owa

Wie

s44

0–57

416

7

n.s.

307–

631;

428

g,h ;

481a,

j ; 75

0–95

0; 1

480a,

c3,

62,

16

8–17

0G

rata

egos

orbu

s m

itsc

huri

nii

Swee

t ro

wan

berr

y G

rana

tnaj

a88

a,b

4Fr

agar

ia ×

ana

nass

a D

.St

raw

berr

yA

llsta

r22

g,h ;

23g,

l66

, 171

Ear

liglo

w28

g,h ;

45g,

l66

, 171

Ken

t8g,

i16

0Po

lka

42g,

l17

2C

ampi

neir

o, T

oyon

oka,

Paj

aro,

Oso

Gra

nde,

D

over

, Maz

i13

, 19,

21,

42,

52,

55g,

l17

3

Late

star

, Del

mar

vel,

Red

Chi

ef ,

Moh

awk,

L

este

r, N

orth

east

er25

, 26,

29,

32,

36,

39g,

l66

Sabl

e, J

ewel

, Ann

apol

is, S

park

le, M

esab

i, E

van

geli

en37

, 38,

39,

41,

44,

47g,

h17

1

Pru

nus

spin

osa

L.

Bla

ckth

orn

n.s.

54a,

b4

Rub

us c

auca

sicu

s Fo

cke

n.a.

n.s.

33g,

h17

4R

ubus

cor

eanu

s M

iq.

n.a.

n.s.

11–3

4g,h

174

Rub

us c

yri J

uzn.

a.n.

s.14

3g,h

67R

ubus

frut

icos

us L

.Sh

rubb

y bl

ackb

erry

Dar

row

, Hul

l tho

rnle

ss, B

lack

sat

in,

Che

ster

, Sm

ooth

stem

, Bla

ck d

iam

ond

, T

hor

nle

ss B

oy S

emb

es

67, 6

9, 7

5, 7

6, 8

7, 1

19,

127g,

h16

4 (con

tinu

ed)



ble

4.1

(Con

tinu

ed)

Ant

hocy

anin

Con

cent

rati

ons

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

Cu

ltiv

arA

nth

ocya

nin

s (m

g/10

0 g

FW)

Ref

eren

ces

Rub

us id

aeus

L.

Red

ras

pber

ryG

len

Am

ple,

Vet

en37

, 57g,

h34

Gle

n Ly

on39

g,h

34, 1

74N

ova

44g,

i16

0A

nne,

Kiw

igol

d, G

old

ie, H

erit

age

<1,

3, 5

, 58g,

j17

5C

anby

, Sen

try,

Aut

umn

Blis

s, S

um

mit

45, 5

3, 7

5, 1

00g,

h66

Tula

mee

n, C

hilli

wac

k, C

omox

, Wil

lam

ette

28–4

4, 5

2–59

, 63,

72g,

j17

6Z

vjoz

dock

a, S

krom

nica

, Bul

gars

kij r

ubin

, R

ubin

brj

ansk

ij, N

orna

, Zu

ravl

ik21

, 26,

29,

35,

42,

66g

6

Sept

embe

r, Su

mne

r29

–41g,

h16

4n.

s.28

–75a,

j ; 65

g,h

177,

178

Rub

us la

cini

atus

Cut

leaf

or

Eve

rgre

en

blac

kber

ryn.

s.91

g,h

178

Rub

us o

ccid

enta

lis L

.B

lack

ras

pber

ryE

arly

swee

t46

4g,h

67Je

wel

197g,

h ; 60

7g,h

66, 6

7M

unge

r62

7g,h

67n.

s.14

5–53

6g,j ;

589g,

h17

7, 1

78R

ubus

sp.

Bla

ckbe

rry

Che

ster

tho

rnle

ss15

3g,h

66C

hoct

aw10

0–10

1g,i ;

114g,

h17

9, 1

80H

ull t

horn

less

172g,

h66

Nav

ado

111–

185g,

i ; 13

6g,h

179,

180

Shaw

nee

122–

128g,

i ; 13

9g,h

179,

180

Trip

le c

row

n10

8–17

6g,i ;

134g,

h66

, 179

AP

F-12

, APF

-8, A

-168

9, C

hick

asaw

, A

-181

7, A

-194

2, A

pach

e, A

-185

7, K

iow

a,

A-1

963,

A-2

049,

A-1

960,

A-1

859,

A-2

005,

A

-190

5

72, 8

5, 1

07, 1

13–1

24, 1

16,

121,

130

, 131

, 131

–363

, 13

2, 1

39, 1

43, 1

66, 1

75,

1208

–122

1g,i

179



Rub

us u

rsin

usM

ario

n bl

ackb

erry

n.s.

62–1

05g,

h ; 15

5g,h

174,

178

Paci

fic d

ewbe

rry

G4-

19, G

4 b

ulk

206,

211

g,h

67R

ubus

urs

inus

× id

aeus

Boy

senb

erry

n.s.

131g,

h ; 21

0h16

5, 1

78

n.a.

, non

e av

aila

ble;

n.s

., no

ne s

peci

fied

.a

HPL

C m

etho

d.

bQ

uant

ifica

tion

bas

ed o

n re

pres

enta

tive

ant

hocy

anid

ins

as s

tand

ard

.c

Qua

ntifi

cati

on b

ased

on

the

repr

esen

tati

ve a

s st

and

ard

s (D

p 3-

gluc

osid

e, C

y 3-

gluc

osid

e, P

t 3-

gluc

osid

e, P

g 3-

gluc

osid

e, P

n 3-

gluc

osid

e, a

nd M

v3-

gluc

osid

e).

dT

he s

ame

cult

ivar

has

dif

fere

nt v

alue

s of

ant

hocy

anin

con

cent

rati

on m

ainl

y d

ue t

o th

e an

alyt

ic t

echn

olog

y ap

plie

d in

dif

fere

nt li

tera

ture

. The

val

ueof

the

ant

hocy

anin

con

cent

rati

on in

bol

d f

ont

is h

ighe

st, w

here

as t

he lo

wes

t is

in it

alic

in t

his

cult

ivar

or

none

-spe

cifi

ed c

ulti

vars

.e

Qua

ntifi

cati

on o

nly

base

d o

n D

p 3-

gluc

osid

e as

sta

ndar

d.

fT

he v

alue

of t

he a

ntho

cyan

in c

once

ntra

tion

in b

old

font

is h

ighe

st, w

here

as th

e lo

wes

t is

in it

alic

am

ong

the

grou

p of

cul

tiva

rs fr

om th

e sa

me

liter

atur

ean

d t

he c

orre

spon

din

g cu

ltiv

ar s

how

s th

e sa

me

fron

t as

its

valu

e of

ant

hocy

anin

con

cent

rati

on.

gpH

dif

fere

ntia

l met

hod

.h

Qua

ntifi

cati

on o

nly

base

d o

n C

y 3-

gluc

osid

e as

sta

ndar

d.

iQ

uant

ifica

tion

onl

y ba

sed

on

Mv

3-gl

ucos

ide

as s

tand

ard

.j

Qua

ntifi

cati

on o

nly

base

d o

n C

y 3-

gala

ctos

ide

as s

tand

ard

.k

Qua

ntifi

cati

on b

ased

on

exti

ncti

on c

oeffi

cien

ts a

nd m

olec

ular

wei

ghts

of

ever

y re

pres

enta

tive

ant

hocy

anin

.lQ

uant

ifica

tion

onl

y ba

sed

on

Pg 3

-glu

cosi

de

as s

tand

ard

.



anthocyanin content may vary with the cultivar, as well as the growingseason and growth conditions. When a new variety of berry is developed,color is one of the most desirable traits that breeders monitor during theselection process. Strawberries with a deep red color are preferred in the freshfruit market. Similarly berries with a bright deep color appear to be moreflavorful to consumers. Sometimes very high concentrations of anthocyaninsin berries results on a very dark color, with berries appearing “black” despitethe fact that the pigments are indeed red to purple. This coloration has resultedin many berries being known as “black,” such as in the case of blackberries,black raspberries, and black chokeberries. These types of berries all havehigh anthocyanin concentrations (Table 4.1). In contrast, some anthocyanin-containing berries have only a rose coloration in the skin because of the lowconcentrations of these pigments. Anthocyanin concentrations in blackchokeberries (Aronia melanocarpa (Michx.) Elliot) reached up to 1458 mg/gfresh weight (FW),3 whereas anthocyanins are not detectable in berries suchas red currant (Ribes × Pallidum cv. White Dutch)4 and gooseberry (Ribesuva-crispa cv. Careless).3

The reported data on anthocyanin concentrations in berries also dependson the methodology used to quantify the pigments. The anthocyanin concen-trations of black currant (Ribes nigrum cv. Ojebyn) reported by differentresearchers ranges from 165 to 412 mg/g FW. These differences may be attrib-utable to inherent variability in the plant material due to factors such as growinglocation and conditions. However, other sources of variability in the data avail-able in the literature may be due to differences in the methodology used forquantitation. Different extraction methods, evaluation assays (spectrophoto-metric method versus high performance liquid chromatography [HPLC] anal-ysis), and the use of various anthocyanin standards in quantitation.5–8

Anthocyanins belong to the class of flavonoid compounds commonlyknown as plant polyphenols, which share the basic structure of a C6–C3–C6carbon skeleton. They are glycosides of polyhydroxy and polymethoxyderivatives of 2-phenylbenzopyrylium or flavylium salts. The anthocyaninpigments consist of two or three portions: the aglycone base (anthocyanidin),sugars, and often acylating groups (Figure 4.1). There are 19 different agly-cone groups known to naturally occur, although only 6 occur frequently.9–13

The aglycones that are more commonly found in berries and in nature arecyanidin, pelargonidin, peonidin, delphinidin, petunidin, and malvidin(Figure 4.1). In addition, a 4-substituted aglycone has recently been foundin strawberries (Fragaria × ananassa Duch.), a 5-carboxypryanopelargonidin3-O-β-glucopyranoside, although present only in small concentrations.14

Anthocyanidins are very unstable and are rarely found in their free formwithin plant tissues. Anthocyanidins occur mainly in the glycosylated forms,where sugar substitution enhances their stability and solubility.15–17 The mostcommon sugar moieties found attached to the aglycones in berries are glu-cose, galactose, arabinose, xylose, sophorose, rutinose, and sambubiose, asmono- and diglycosides (Figure 4.2), and the most widespread anthocyaninin nature is cyanidin 3-glucoside. The 3-hydroxyl position is the most common



place for glycosylation, and monoglycosylated anthocyanins will have thesugar in that position. If the anthocyanin is di- or triglycosylated then theadditional sugars may attach to the 3 or 5 position of the aglycone and areless frequently found in glycosylation in position 7. Although other antho-cyanin glycosylation patterns have been reported in nature, such as glyco-sylations on the B ring of the anthocyanidin (Figure 4.1), these glycosylationshave not been found in berries to date.

Although uncommon in berries, some anthocyanins may be acylated witharomatic acids, such as p-coumaric and caffeic acids or aliphatic acids, suchas malonic acids (Figure 4.3). Because each aglycone might be glycosylatedand acylated by different sugars, cinnamic acids, and aliphatic acids, close to600 structurally distinct anthocyanins have been identified in nature.18

The anthocyanin composition in berries (Table 4.2) is very differentamong species, but quite similar within the same species. For this reason,anthocyanin profiles have been regarded as fingerprints for a specific com-modity. New analytical techniques have allowed for characterization of theminor components previously reported as unknown. The coupling of

Figure 4.1 Structures of anthocyanidins commonly found in berries.

510 (bluish-red)

508 (red)

506 (orange-red)

508 (red)

506 (orange-red)

494 (orange)

max (nm) visiblespectra

OCH3

OH

H

OH

H

H

R2

331

317

301

303

287

271

Molecularweight

OCH3

OCH3

OCH3

OH

OH

H

R1

Substitutes

Peonidin

Pelargonidin

Malvidin

Petunidin

Cyanidin

Anthocyanidins

Delphinidin

B

C

O+

OH

OH

HO

R1

OH

A

3

3’

5’

4’

5

7R2



reverse-phase HPLC and mass spectrometery (MS) allows the molecules tobe characterized by retention time, ultraviolet (UV)-visible response, andmass spectral information for the individual components and fragments,even when the compounds are present in low concentrations. This powerfultechnique has gained popularity in recent years and may explain why com-positional anthocyanin data have dramatically increased over the lastdecade. Analysis methods and culture conditions may cause a slight differ-ence in anthocyanin profiles of the same berry species. One example is theAmerican cranberry (Vaccinium macrocarpon Aiton.), which contains cyanidinand peonidin 3-galactosides and 3-arabinosides as major anthocyanins.19,20

Figure 4.2 Typical glycosylations found in berry anthocyanins.

Figure 4.3 Acylations found in berry anthocyanins.

O

OHOHHO

HO

OH

β-D-Glucose

O

OH

HO

OHHO

H3C

β-D-Galactose

O

OHOHHO

HO

β-D-Xylose

OOH

HO

OHHO

β-D-Arabinose

Rutinose(6-O-L-rhamnosyl-D-glucoside)

O

OHHO

OHHO

O

OH3C

HOHO OH

O

HOHO

HO

O

OH

HOHO

HOO

OH

Sophorose(2-O-β-D-glucosyl-D-glucoside)

OHO

HO

HO

O

OH

HOHO O

OH

Sambubiose(2-O-β-D-xylosyl-D-glucoside)

p-courmaric acid Caffeic acid

Malonic acid

HO OH

O O

HO

HO

O

OH

HO

O

OH

OHH3C

O

Acetic acid

OH

OHO

O

Succinic acid


Chapter 4: Natural pigments of berries: Functionality and application 117Ta

ble

4.2

Ant

hocy

anin

Com

posi

tion

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

An

thoc

yan

in c

omp

osit

ion

Ref

eren

ces

Cap

rifo

liace

aeSa

mbu

cus

cana

dens

is L

.C

omm

on e

lder

berr

y/

Am

eric

an e

lder

berr

yC

y 3-

(6-p

-cou

mar

oyl-

2-xy

l)-(

1→2)

glc-

5-gl

c; C

y 3-

sam

-5-g

lc; C

y 3,

5-d

iglc

; Cy

3-sa

m; C

y 3-

glu;

Cy

3-(6

-p-c

oum

aroy

l-2-

xyl)

-glu

-5-g

lu; C

y 3-

(6- p

-cou

mar

oyl-

2-xy

l)-(

1→2)

glc

181

Sam

bucu

s ni

gra

L.

Eur

opea

n el

der

berr

yC

y 3-

sam

; Cy

3-gl

c; C

y 3-

sam

-5-g

lc; C

y 3,

5-d

iglc

;Cy

3-ru

t; Pg

3-g

lc;

Pg 3

-sam

3, 1

81

Ela

eoca

rpac

eae

Ari

stot

elia

chi

lens

is

(Mol

.) St

untz

Maq

uei/

mac

qui

Dp

3-sa

m-5

-glc

; Dp

3-gl

c; D

p 3,

5-d

iglc

; Dp

3-sa

m; C

y 3-

sam

-5-g

lc;

Cy

3-gl

c; C

y 3,

5-d

iglc

; Cy

3-sa

m15

8

Eri

cace

aeV

acci

nium

ang

usti

foliu

m

Ait

onL

owbu

sh b

lueb

erry

Dp

3-ga

l; D

p 3-

glc;

Cy

3-ga

l; D

p 3-

ara;

Cy

3-gl

c; P

t 3-g

al; C

y 3-

ara;

Pt

3-g

lc; P

n 3-

gal;

Pt 3

-ara

; Pn

3-gl

c; M

v 3-

gal

182

Vac

cini

um a

rcto

stap

hylo

s L

.C

auca

sian

w

hort

lebe

rry

Dp

3-gl

c; P

t 3-

glc;

Mv

3-gl

c18

3

Vac

cini

um a

shei

Rea

de

cv. T

ifbl

ueR

abbi

teye

blu

eber

ry/

smal

lflow

er

blue

berr

y

Dp-

3-ga

l; D

p-3-

glc;

Cy-

3-ga

l; D

p-3-

ara;

Cy-

3-gl

c; P

t-3-

gal;

Pt-3

-glc

; Pn

-3-g

al; P

t-3-

ara;

Mv-

3-ga

l; M

v-3-

glc;

Pn-

3-ar

a; M

v-3-

ara

19

Vac

cini

um c

orym

bosu

m

cv. B

luec

rop

Hig

hbus

h bl

uebe

rry

Dp

3-ga

l; D

p 3-

glc;

Cy

3-ga

l; D

p 3-

ara;

Cy

3-gl

c; P

t 3-g

al; C

y 3-

ara;

Pt

3-g

lc; P

n 3-

gal;

Pt 3

-ara

; Mv

3-ga

l; M

v 3-

glc;

Pn

3-ar

a; M

v 3-

ara;

Dp

3-(a

cety

l)-g

lc; P

t 3-

(ace

tyl)

-glc

; Mv

3-(a

cety

l)-g

lc

184

Vac

cini

um m

acro

carp

on

Ait

on.

Am

eric

an c

ranb

erry

Cy

3-ga

l; C

y 3-

ara;

Pn

3-g

al; P

n 3

-ara

; Cy

3-gl

c; P

t 3-

gal

19C

y 3-

gal;

Cy

3-ar

a; P

n 3

-gal

; Pn

3-a

ra; C

y 3-

glc;

Pn

3-gl

c; D

p 3-

gal;

Dp

3-gl

c20 (c

onti

nued

)



ble

4.2

(Con

tinu

ed)

Ant

hocy

anin

Com

posi

tion

in E

dib

le B

erri

es

Scie

nti

fic

nam

eC

omm

on n

ame

An

thoc

yan

in c

omp

osit

ion

Ref

eren

ces

Vac

cini

um

mem

bran

aceu

m

Dou

glas

ex

Torr

.

Thi

nlea

f hu

ckle

berr

yD

p 3-

gal;

Dp

3-gl

c ; D

p 3-

ara;

Cy

3-ga

l; C

y 3-

glc;

Pt 3

-gal

; Cy

3-ar

a;

Pt 3

-glc

; Pn

3-ga

l; Pt

3-a

ra; M

v 3-

gal;

Pn 3

-glc

; Pn

3-ar

a; M

v 3-

glc;

M

v 3-

ara

63

Vac

cini

um m

yrti

llus

L.

Bilb

erry

/w

hort

lebe

rry

Dp

3-g

lc; C

y 3-

gal;

Cy

3-ar

a;P

t 3-g

lc; M

v 3-

glc;

Dp

3-g

al; D

p 3

-ara

; P

t 3-

gal;

Pt

3-ar

a; M

v 3-

gal;

Mv

3-ar

a; P

n 3-

gal;

Pn 3

-ara

7

Cy

3-ar

a; C

y 3-

gal;

Cy

3-gl

c; D

p 3-

ara;

Dp

3-ga

l; D

p 3-

glc;

Pt 3

-ara

; Pt

3-g

al; P

t 3-g

lc; P

n 3-

gal;

Pn 3

-glc

; Mv

3-ar

a; M

v 3-

gal;

Mv

3-gl

c;

Pn 3

-ara

185

Vac

cini

um o

vatu

m P

ursh

Cal

ifor

nia

huck

lebe

rry

Dp

3-ga

l; D

p 3-

glc

; Dp

3-ar

a; C

y 3-

gal;

Cy

3-gl

c; P

t 3-g

al; C

y 3-

ara;

Pt

3-g

lc; P

n 3-

gal;

Pt 3

-ara

; Mv

3-ga

l; Pn

3-g

lc; P

n 3-

ara;

Mv

3-gl

c;

Mv

3-ar

a

63

Cy

3-gl

c; P

n 3

-glc

; Cy

3-ga

l; C

y 3-

ara;

Dp

3-gl

c; P

n 3-

glc;

Pn

3-ar

a;

Pt 3

-glc

; Mv

3-gl

c16

2

Vac

cini

um o

xyco

ccus

L.

Smal

l cra

nber

ryC

y 3-

gal;

Cy

3-gl

c; C

y 3-

ara;

Pn

3-ga

l; Pn

3-g

lc; P

n 3-

ara;

Dp

3-gl

c;

Dp

3-ga

l20

Vac

cini

um u

ligin

osum

L.

Bog

blu

eber

ry/

bog

who

rtle

berr

yM

v 3-

glc;

Mv

3-ar

a; M

v 3-

gal;

Dp

3-g

lc; D

p 3

-ara

; Dp

3-g

al; C

y 3-

glc;

Cy

3-ar

a; C

y 3-

gal;

Pt

3-gl

c; P

t 3-

ara;

Pt

3-ga

l: P

n 3

-glc

;Pn

3-ar

a; P

n 3-

gal

163

Vac

cini

um v

itis

-ida

ea L

.L

ingo

nber

ry/

mou

ntai

n cr

anbe

rry/

cow

berr

y

Cy

3-ga

l; C

y 3-

ara;

Cy

3-gl

c ; D

p 3-

glc

7, 1

86

Gro

ssul

aria

ceae

Rib

es u

va-c

risp

aG

oose

berr

yC

y 3-

glc,

Cy

3-ru

t, C

y 3-

(6- p

-cou

mar

oyl)

-glc

; Pn

3-gl

c; P

n 3-

rut;

Cy

3-xy

l; C

y 3-

(6-c

affe

oyl)

-glc

3

Rib

es n

igru

mB

lack

cur

rant

Dp

3-g

lc;D

p 3

-ru

t; C

y 3-

glc;

Cy

3-ru

t; Pt

3-g

lc; P

g 3-

glc;

Pt

3-ru

t; Pn

3-g

lc; D

p 3-

xyl;

Pg 3

-rut

; Pn

3-ru

t; C

y 3-

xyl;

Pt

3-(6

- p-c

oum

aroy

l)-g

lc; C

y 3-

(6- p

-cou

mar

oyl)

-glc

3, 7

, 187

Rib

es ×

Pal

lidum

Red

cur

rant

Cy

3-(2

-glc

)-ru

t; C

y 3-

sam

; Cy

3-gl

c; C

y 3-

(2-x

yl)-

rut;

Cy

3-ru

t8


Chapter 4: Natural pigments of berries: Functionality and application 119R

ibes

rub

rum

cv.

Red

la

keC

ulti

vate

d c

urra

ntC

y 3-

(xyl

)-ru

t; C

y 3-

rut;

Cy

3-sa

m; D

p 3-

sam

; Cy

3-so

ph; C

y 3-

(glc

)-ru

t; C

y 3-

glc

3, 1

88

Lau

race

aeLa

urus

nob

ilis

L.

Swee

t ba

yC

y 3-

glc;

Cy

3-ru

t; Pn

3-g

lc; P

n 3-

rut

189

Mor

acea

eM

orus

nig

ra L

.B

lack

mul

berr

yC

y 3-

soph

; Cy

3-gl

c; C

y 3-

rut;

Pg 3

-glc

; Pg

3-ru

t18

5M

yrta

ceae

Eug

enia

um

belli

flora

O.

Ber

gB

agua

çuD

p 3-

glc;

Cy

3-gl

c; P

t 3-

glc;

Pg

3-gl

c; P

n 3-

glc;

Mv

3-gl

c16

6

Rha

mna

ceae

Rha

mnu

s al

ater

nus

L.

Ital

ian

buck

thor

nD

p 3

-ru

t; P

t-3-

rut;

Cy

3-ru

t; Pn

3-r

ut; M

v 3-

rut;

Pg 3

-rut

190

Ros

acea

eA

roni

a m

elan

ocar

pa

(Mic

hx.)

Elli

otB

lack

cho

kebe

rry

Cy

3-ga

l; C

y 3-

glc;

Cy

3-ar

a; C

y 3-

xyl ;

Pg 3

-ara

; Pg

3-ga

l3,

191

Frag

aria

× a

nana

ssa

D.

cv. C

amar

osa

Stra

wbe

rry

Pg

3-gl

c; P

g 3-

rut;

Pg 3

-ara

; Pg

3-(m

alon

yl)-

glc;

Pg

3-ac

etyl

-glc

; Pg

3-(

succ

inyl

)-gl

c; C

y 3-

glc;

Cy

3-ru

t; C

y 3-

(mal

ony)

-glc

-5-g

lc;

5-ca

rbox

ypry

anop

elar

goni

din

3-g

lc

14, 1

92–1

94

Rub

us id

aeus

L. c

v. G

len

Am

ple

Red

ras

pber

ryC

y-3-

soph

; Cy-

3-(2

–glc

)-(1

→2)

rut;

Cy-

3-gl

c; P

g-3-

soph

; Cy-

3-ru

t; Pg

-3-(

2-gl

c)-(

1→2)

rut;

Pg-3

-glc

; Pg-

3-ru

t19

5

Rub

us la

cini

atus

Cut

leaf

bla

ckbe

rry/

ever

gree

n bl

ackb

erry

Cy

3-gl

c; C

y 3-

ara;

Cy

3-(6

-mal

onyl

)-gl

c17

8

Rub

us o

ccid

enta

lis L

.B

lack

ras

pber

ryC

y 3-

glc;

Cy

3-sa

m; C

y 3-

(xyl

)-ru

t; C

y 3-

rut;

Pg 3

-rut

196

Rub

us s

p.B

lack

berr

yC

y 3-

gal;

Cy

3-gl

c; C

y 3-

ara;

Cy

3-xy

l; M

v 3-

glc;

Pg

3-gl

c18

5R

ubus

urs

inus

Mar

ion

blac

kber

ryC

y 3-

(6- p

-cou

mar

oyl)

-glc

; Cy

3-(6

-mal

onyl

)-gl

c17

8R

ubus

urs

inus

× id

aeus

Boy

senb

erry

Cy

3-(6

-p-c

oum

aroy

l)-g

lc-5

-glc

; Cy

3-gl

c17

8C

y 3-

soph

; Cy

3-gl

c-ru

t; C

y 3-

glc;

Cy

3-ru

t17

7

Ind

ivid

ual a

ntho

cyan

ins

in b

old

fon

t ar

e m

ajor

com

pone

nts

in a

ntho

cyan

in p

rofil

e.A

rabi

nosi

de

(ara

); cy

anid

in (

Cy)

; del

phin

idin

(D

p); d

iglu

cosi

de

(dig

lc);

gala

ctos

ide

(gal

); gl

ucos

ide

(glc

); m

alvi

din

(M

v); p

elar

goni

din

(Pg

); pe

onid

in(P

n); p

etun

idin

(Pt

); ru

tino

sid

e (r

ut);

sam

bubi

osid

e (s

am);

soph

oros

ide

(sop

h); x

ylos

ide

(xyl

).



However, the presence of different minor anthocyanins, including cyanidin3-glucoside and petunidin 3-galactosides,19 cyanidin and peonidin 3-gluco-sides, and delphinidin 3-galactoside and 3-glucoside, has been reported.20

4.2.2 Other pigments in berries

Anthocyanins are responsible for the color of most berries and are the mostprevalent flavonoids in berries.4,21 However, depending on the specific spe-cies of berry, other classes of pigments may also play an important role inberry color. Flavonoids, chlorophylls, carotenoids, and even betalains havebeen found in various berry species as contributors to the characteristicvisual appearance. Chlorophyll, carotenoids, and many flavonoids areknown to coexist with anthocyanins, but anthocyanins and betalains havenever been found to coexist in the same plant material. Therefore anthocyanin-containing berries will not have betalains, and vice versa.

4.2.2.1 ChlorophyllsBefore maturation and ripening, berries usually exhibit a green colorationbecause of the presence of chlorophylls. Chlorophylls are by far the mostabundant pigments in plants. However, as the berry fruit matures, chloro-phyll disappears and the plant synthesizes other pigments that provide aripe appearance on the skin of the berry.

4.2.2.2 Flavonols and flavan-3-olsFlavonols and flavan-3-ols, are cream to yellow flavonoids that are abundantin berries. These compounds are known to be major contributors to the colorof some yellow and white berry species, many times in combination withcarotenoids (Table 4.3). Berries that contain anthocyanins usually haveconsiderable amounts of other flavonoids as well. Although the flavonoidcontribution to color is minor and usually masked by the more colorfulanthocyanins, they do play a role in differences in hue among berries. Amonganthocyanin-containing berries, high concentrations of quercetin (210 to 680mg/kg FW) have been reported in bog whortleberries (also known as bogblueberry [Vaccinium uliginosum L.]), black chokeberries (350 mg/kg FW),elderberries (Sambucus nigra L.) (330 mg/kg FW), small cranberries (Vaccin-ium oxycoccos L.) (210 mg/kg FW), and blackthorns (Prunus spinosa L.) (210mg/kg FW).4 Another flavonol, myricetin, is abundant in bog whortleberry(200 to 340 mg/kg FW).4 Total flavonols in black currants has been found tobe about 100 mg/kg FW.22 Flavan-3-ols that are present as monomers, oli-gomers, or condensed forms (proanthocyanidins) can contribute to color.While the content proanthocyanidins of berries generally is around 100 mg/100 g (FW), some others such as chokeberries have much higher levels ofproanthocyanidins, with about 664 mg/100 g FW.3

Berries that lack anthocyanins owe their color to other pigments (Table 4.3).In these berries, other flavonoids may play a major role in the visual appear-ance of the berry. Along these lines, flavonols presented in green currant(Ribes nigrum L.) were about 80 mg/kg FW.22



Tabl

e 4.

3O

ther

Pig

men

ts in

Non

anth

ocya

nin-

Con

tain

ing

Ber

ries

Scie

nti

fic

nam

eC

omm

on

nam

eP

igm

ents

Com

pos

itio

nC

once

ntr

atio

n

(mg/

kg F

W)

Ref

eren

ces

Ara

ceae

Aru

m it

alic

um P

. Mill

.It

alia

n lo

rds

and

lad

ies

Car

oten

oid

s50

a19

7C

hlor

ophy

ll10

a

Ela

eagn

acea

eE

laea

gnus

um

bella

te T

hunb

.A

utum

n ol

ive

Car

oten

oid

sly

cope

ne, a

nd c

rypt

oxan

thin

, an

d c

arot

ene,

lute

in, p

hyto

ene,

an

d p

hyto

flue

ne

469

24

Hip

poph

ae r

ham

noid

es L

.Se

a buck

thor

n be

rrie

s

Car

oten

oid

sZ

eaxa

nthi

n (d

ipal

mit

ate)

20–3

023

Flav

onol

sM

yri;

quer

; iso

rham

neti

n84

; 172

; 167

4M

yri;

quer

; kae

mn.

d.;

62; n

.d.

198

Gro

ssul

aria

ceae

Rib

es n

igru

m L

.G

reen

cu

rran

tFl

avon

ols

Myr

i; qu

er; k

aem

8; 3

3; 1

24

7; 6

3; 7

8n.

d.;

32; n

.d.

198

Rib

es ×

pal

lidum

cv.

Whi

te

Dut

chW

hite

cu

rran

tFl

avon

ols

Myr

i; qu

er; k

aem

1; 1

2; t

race

4n.

d; 7

; n.d

.19

80.

4; 5

; n.d

.8

Rib

es u

va-c

risp

a L

.Ye

llow

go

oseb

erry

Flav

onol

sM

yri;

quer

; kae

mTr

ace;

13;

14

n.d

.; 18

; 16

198

Sola

nace

aeLy

cium

bar

baru

mW

olfb

erry

Car

oten

oid

sZ

eaxa

nthi

n (d

ipal

mit

ate)

820b

23

anm

ol/

g FW

.bm

g/g

DW

.M

yri,

myr

icet

in; q

uer,

quer

ceti

n; k

aem

, kae

mpf

erol

.



4.2.2.3 CarotenoidsCarotenoids are a class of natural fat-soluble pigments responsible for the red,orange, and yellow pigment hues in plants. Sea buckthorn berries (Hippophaerhamnoides L.) contain not only flavonols such as myricetin, quercetin, isorham-netin (about 84, 172, and 167 mg/kg FW, respectively),4 but also zeaxanthin(about 20 to 30 mg/kg FW).23 Lycopene accounts for 384 mg/kg of freshautumn olive berries (Elaeagnus umbellate Thunb.) and up to 82% of the caro-tenoid concentration (about 469 mg/kg FW), producing a pleasant red color.24

4.2.2.4 BetalainsPhytolaccanin (or betanin) provides a red-violet color to pokeberries (Phy-tolacca americana), which is rather unusual because most red-/purple-coloredberries owe their color to anthocyanins. However, these berries contain atoxic saponin, phytolaccatoxin, that must be removed prior to use of thepigment as a food colorant.25

4.3 Changes in berry pigments during processing and storage

Many changes take place during maturation and postharvest handling of fruits,including changes in the pigment concentration and composition. In general,the chlorophyll concentration decreases, while other pigments become moreprominent. The concentrations of carotenoids and anthocyanins increases orbecomes more evident (because of the decrease in chlorophyll), resulting inwonderful berry colors ranging from yellow to red, purple, blue, and almostblack. The types of pigments produced and their concentrations depend largelyon the genetic material, but they are also affected by many other factors, includ-ing light, temperature, and soil nutrients. Carotenoids are stable and remain inthe tissues until senescence, while anthocyanins are present in the cell’s sapand are susceptible to degradation by different enzymes.

Color is one of the main attributes used by consumers to judge thequality of a fruit. Also, berry pigments may provide health benefits, so it islikely that pigment content will become increasingly important to consumersand producers in the future. Therefore harvesting and processing conditionsshould be optimized to ensure color quality. This is only achieved if thepigments are allowed to develop in the tissues under conditions that mini-mize pigment degradation. The effects of harvesting, processing, and storageon pigment and color stability in berries and berry products are discussedhere, with a special focus on anthocyanin pigments and red color.

4.3.1 Changes during fruit ripening, harvesting, and storage of fresh fruit

Fruit maturity at harvest has an impact on the final berry’s color quality andpigment composition. During ripening, anthocyanins accumulate in the fruit,which may take 3 to 6 days under warm weather conditions or noticeably



longer with cold temperatures. The synthesis of anthocyanins depends onmany ecological and physiological factors, but also on the berry species andcultivar. In some raspberry cultivars, anthocyanin biosynthesis proceedsuniformly with ripening, however, other cultivars show peaks of maximumconcentration.26 The accumulation of anthocyanins in blackberries linearly cor-relates to the soluble solids:acid ratio. Therefore color changes in the fruit maybe attributable to both pigment synthesis and changes in the acidity of the fruit.

Fruit that has been harvested before ripening may synthesize pigmentsduring storage under favorable conditions. Strawberries picked at half colorare smaller and less flavorful than strawberries picked fully colored. Aftera period of ripening at 21°C, differences in the color of both were not appre-ciable.27 Strawberries harvested underripe can develop full red color, and theprocess is temperature dependent,28,29 favored by light at room temperature.30

Cleaning and packing of berry fruits needs to be done with special careto avoid bruising, since bruises can result in a loss of color and pigmentaround the affected areas.31

4.3.2 Processing and storage of berry products

Storage temperature and conditions affect pigment degradation. Cranberriesstored at 20°C showed an anthocyanin loss in 62% of the fruit, but theyexhibit a loss of only 20% when stored at 7°C. Storage of cranberries at 0°Cdid not cause a loss of anthocyanin content, suggesting that the loss of colorobserved at higher temperatures might be related to enzymatic activity.Treatment with ethylene can enhance anthocyanin production and colordevelopment, especially if the berries are exposed to light.32 Fresh, well-coloredlingonberries stored for several weeks at 1°C to 2°C with little detrimentaleffects to pigments and fruit quality.33 However, an increase in temperatureto 5°C shortens the shelf life of the berries almost half, making storagetemperature a key factor in the quality of these berries.

Storage in controlled atmosphere protects the integrity of the fruit bysuppressing rooting and keeping the pigment content relatively unchangedduring storage. Red raspberries stored under regular and controlled atmo-spheres showed a variety of berry colors. Berries stored under normal atmo-spheres showed darker colors, with pigment levels increasing after 7 days.In contrast, storage at the same temperature and time, but under controlledatmosphere (10% oxygen, 15% to 31% carbon dioxide), prevents colorchanges during storage.34

Berries can be very successful in the fresh market because their organo-leptic characteristics are usually favored by consumers. Their shelf life istypically short and much effort has been invested on extending shelf life. Inaddition, some berries, such as cranberries, are not consumed raw, but ratherin a variety of forms as processed products such as juices and sauces. Theprocessing techniques used for berry processing vary and the effects of pro-cessing and storage on the pigment quality of berries have been extensivelystudied. Factors that favor anthocyanin stability are the absence of oxygen,low pH, and low processing/storage temperatures.



4.3.2.1 Juice/Wine processingBerry juices are very popular in the American market. Some berries arealso suitable for wine production. Deeper colored wines are obtained bythermovinification of fermenting berries “on the skin.” With cold pressing,only about one-quarter of the extractable color is obtained. The use of enzymesduring the processing of juices is a common practice in the food industry.Crushed berries are exposed to enzymes to increase juice yield and colorintensity. When a berry is crushed, the soluble pectins present in the berrycan cause gelling of the mash before the juice can run off the press.35 Addingpectolytic enzymes to the mash prevents the formation of pectin gel and helpsproduce a good quality berry juice. Another practice is the use of enzymaticliquefaction of the fruit, where a combination of pectinases, pectic lyases, andcellulases can liquefy the fruit, resulting in increased yields and sweetness.However, these enzymes usually have other side effects and should be care-fully selected to avoid pigment destruction. Deglycosylation of anthocyaninsis due to a side effect of enzyme preparations that results in anthocyanindegradation and color loss. This has been reported for raspberry, strawberry,and cranberry juices, as well as for raspberry and blackberry wine.36 Thereforeit is recommended that processors do a glucosidase activity screening ofenzyme preparations prior to berry juice and wine production.37

Cranberry juice of superior quality can be obtained from fruit harvestedat full ripeness.38 Blanching of the whole fruit inactivates oxidizing enzymes,leading to a higher anthocyanin concentration in the juice.

Freezing and thawing berries increases juice yields up to 50% and antho-cyanin content up to 15-fold.39 Anthocyanin degradation during juice storagegreatly depends on the storage temperature. For example, 40% of the totalanthocyanins in black currant juice (pH 2) disappeared after 9 weeks ofstorage at 4°C, while all anthocyanins were depleted after 9 weeks at 37°C.40

Unfortunately the color of berry juices is susceptible to degradation,resulting in a dull, brownish color. Various attempts have been made tostabilize the color of berry juices. Addition of sulfur dioxide can slow downthe degradation of anthocyanins in strawberry juice and puree, while ascorbicacid has the opposite effect.41 The use of phenolic acids has been recom-mended to enhance the color and stability of berry juices. Sinapic acidimproves strawberry and raspberry juice color, while rosmarinic acidimproves the color of lingonberry and cranberry juices.42 The interactionsbetween anthocyanins and other phenolics are defined as copigmentation,and the mechanism of action is due to the spatial arrangement of the mol-ecules. However, complexation of anthocyanins with some of these phenolicsthrough condensation reactions has been reported.42

4.3.2.2 Heat treatmentThe color, flavor, and texture of fruit are all affected by thermal processing.Heat is one of the most destructive variables in fruit processing and theprocessing conditions should be designed to minimize quality losses whileensuring safety.



Pigments in general can be detrimentally affected by heat. Chlorophylls canbe degraded into the brown pheophytins, carotenoids converted to epoxides, andanthocyanins can be degraded into a number of colorless and orange to brownderivatives. However, heat can also help inactivate oxidizing enzymes that couldpotentially destroy pigments present in the fruit. Therefore careful control oftemperature conditions may actually benefit the color of the final product.

During canning, anthocyanins can rapidly react with the metal walls ofunlacquered cans, thus it is necessary to use an acid-resistant lacquer in thecans to avoid interaction, protect product quality, and protect can integrity.

Heat can favor two types of discolorations associated with anthocyanins:the first one is when leucoanthocyanidins are converted into anthocyanins.This may cause pink discoloration in fruit that originally appeared cream oryellow in color. The second type involves enzymatic browning, which canbe prevented by blanching and the addition of organic acids, such as ascorbic,malic, and citric acid.

The chemical structure of anthocyanins has an effect on their resistanceto degradation. In general, acylated pigments are more stable than theirnonacylated counterparts. Also, anthocyanins with more glycosidic substi-tutions have been found to possess increased stability. In addition, higherpigment concentration and copigmentation with other phenolics present inthe matrix can contribute to an increased stability of anthocyanins.

4.3.2.3 Fruit preserves and jams/syrupsProcessing conditions for the production of berry jams can have drasticconsequences on anthocyanins and yield a high percentage loss (20% to 50%)of anthocyanin pigments.43 The variety of fruit, method of preparing the jam,and freezing of the fruit for long periods prior to processing are factors thataffect the final anthocyanin concentration in jam. Degradation of black cur-rant anthocyanins in syrup follows first-order kinetics, as well as degradationof the red color as measured by the Hunter “a*” value.44 Light exposureaccelerated degradation of pigments, while degassing of the syrup did nothave an impact on pigment degradation. Anthocyanin degradation in syrupcontaining high concentrations of pigment is lower than in syrups with loweranthocyanin concentrations, suggesting that higher anthocyanin concentra-tions may exert a protective effect over pigment degradation. The use ofadditives to extend the shelf life of jam can have an impact on anthocyaninstability. Ascorbic acid can accelerate anthocyanin degradation, and the pHof the product will have an impact on the color and stability characteristics.However, the addition of benzoate, a commonly used antimicrobial agent,does not influence anthocyanin or color degradation.43

Storage temperatures of jams can also have an impact on color andpigment stability. Jams stored at 37°C show 98% pigment degradation after3 months of storage. The same product stored at 20°C showed similar deg-radation after 6 months. Fortunately color degradation is not as drastic aspigment degradation, suggesting that polymerized pigments and copigmen-tation reactions are important for the color of the product during storage.



4.3.2.4 FreezingPreservation of fruits by freezing is less destructive to the natural pigments thanother processes. De Ancos et al.45 found that the effects of freezing on the antho-cyanin content in raspberries depended on the pH of the fruit, the initial antho-cyanin content, and the concentration of sugars and organic acids. Freezingunripe blackberries results in color changes from blue to red. These changeswere attributed to the lowering of the blackberry’s pH caused by disruption ofthe cellular structure (plasmolysis), which leads to the mixing of cellular fluidspreviously compartmentalized.46 However, other researchers have not reportedcolor changes due to freezing of blackberries,47 suggesting that the effects offreezing might depend on the temperature and conditions used during thefreezing and storage processes. In general, rapid freezing and low storage tem-peratures better preserve the structure of the tissues and help minimize tissuedamage. These conditions should also favor pigment integrity in the tissues.

4.4 Health benefits of anthocyaninsNumerous epidemiologic studies have shown that high consumption of fruitsand vegetables is associated with a lower risk of chronic diseases, such ascancers, cardiovascular diseases, cataracts, and hypertension. A report com-missioned by the World Cancer Research Fund and the American Institute forCancer Research stated that about 20% or more of all cancer cases are prevent-able with a diet high in various vegetables and fruits (about 400 to 800 g/day).48

Many studies are now focused on trying to determine what compoundsin fruits and vegetables are responsible for these protective effects. Researchover the last decade has increasingly shown that plant pigments providemuch more than just color. Natural pigments are potent antioxidants andseem to possess a number of potential health benefits.

Anthocyanins are the most abundant flavonoids in the diet, and dailyconsumption of about 200 mg/person was estimated in the 1970s,49 whichis much higher than the average intake of other flavonoids (23 mg/person).50

Therefore anthocyanins are receiving positive attention as major dietaryphytonutrients in berries. Many in vitro and in vivo studies related to thebiological activities of anthocyanins or anthocyanin-rich berries have beendone or are under way around the world.

4.4.1 Antioxidants

Living organisms have a reduction-oxidation (redox) system that tries tokeep life in a healthy balance. Free radicals are necessary for the living stateof cells and organisms.51,52 If more radicals than needed are generated, thisleads to stress situations. The formation of large amounts of free radicalsmay lead to aging and many degenerative diseases.53–58

In numerous studies, berry extracts and juices have been shown to possesshigh antioxidant capacity.59–61 Different genera, species, and even varieties ofberries, as well as the maturity status, have been shown to result in different



antioxidant capacities.21,62–65 A study comparing the antioxidant activity of dif-ferent berries found that strawberries had the highest oxygen radical absorbancecapacity (ORAC) followed by black raspberry (Rubus occidentalis L.), blackberries(Rubus sp.), and red raspberries (Rubus idaeus L.).66 Maturity at harvest also hadan impact on ORAC, anthocyanin, and total phenolic content.21 Blackberries andstrawberries exhibited the highest ORAC values during the green stages,whereas red raspberries had the highest ORAC activity in the ripe stage.66

Berry fruits contain a wide range of flavonoids and phenolic acids thatshow antioxidant activity, and among those, anthocyanins are the majorconstituents in most berries. Different studies have shown a linear relation-ship between ORAC and anthocyanin content21,66 or total phenolic contentin berries.67 The antioxidant activity of berry phenolics also depends on theoxidation model system applied, as well as the oxidation products moni-tored.61,65,68 This makes it difficult to interpret and compare antioxidant data,since results may seem contradictory. For instance, using the inhibition ofhexanal formation in low-density lipoprotein (LDL), berry extracts are effec-tive in the order: blackberries > red raspberries > blueberries > strawberries.However, when compared in terms of inhibition of hexanal formation inlecithin liposomes, the extracts were effective in the order: blueberries > redraspberries > blackberries > strawberries.61

The relationship between anthocyanin structure and antioxidant capacityhas been explored. Depending on the anthocyanidin, different glycosylationpatterns either enhanced or reduced the antioxidant power.68 Anthocyaninshave been shown to chelate metal ions at moderate pH levels with theirionized hydroxyl groups of the B ring.69 Cyanidin, with 3,4-dihydroxy sub-stituents in the B ring, have very effective radical scavenging structures.60,62

Glycosylation and acylation of the anthocyanidins may also affect the totalantioxidant capacity.60,70,71 Different sugars may have various effects on theanthocyanin’s antioxidant activity.60 Acylation with cinnamic acids mayincrease the antioxidant capacity of anthocyanins because many of thesephenolics may be antioxidants as well.

4.4.2 Cancer chemoprotective properties

Carcinogenesis is a multistage process that involves three steps: initiation,promotion, and progression. Numerous anticarcinogenesis studies haveshown that phytochemicals from fruits and vegetables play an importantrole in chemoprevention48 suppressing different steps of the carcinogenesisprocess.72 Berry fruits have a wide range of phytochemicals, primarily antho-cyanins, which are the major components in most berries.64 The potential ofberries to reduce the risk of many cancers has been shown from recent cellculture experiments as well as animal and human intervention studies. Thepossible mechanisms related to the anticarcinogenesis of berries involveantioxidant activity, detoxification activity, antiproliferation, induction ofapoptosis, and antiangiogenic activity.72–88 The effects of berry fruits in inhibit-ing the growth of neoplastic cells are summarized in Table 4.4.



ble

4.4

Rep

orte

d A

ntip

rolif

erat

ive

Eff

ects

of

Ber

ries

Scie

nti

fic

nam

eC

omm

on n

ame

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Anthocyanin-rich extracts or foods have been found to induce phase IIenzymes (glutathione-S-transferases [GST], uridine diphosphate-glucurono-syltransferase [UGT], quinone reductase [QR], and others), which can inac-tivate carcinogens activated by phase I enzymes, thus inhibiting the damageof carcinogens to DNA. Isolated anthocyanin fractions of four Vacciniumspecies (lowbush blueberry, bilberry, cranberry, and lingonberry) were foundto be active QR inducers in vitro.76 Concord grape juice, rich in anthocyanins,significantly inhibits in vivo mammary 7,12-dimethylbenz[a]anthracene(DMBA)-DNA adduct formation, which can be partially explained byincreased liver activity of the phase II metabolizing enzyme (GST).77

Anthocyanin-rich extracts from grape (Vitis vinifera), bilberry (Vaccinium myr-tillus L.), and chokeberry have been shown to inhibit by 50% proliferation ofhuman colon tumor cell lines (HT-29) at 25 to 75 µg/ml (equivalents as cyanidin3-glucoside), with little effect on normal colon cells (NCM460). However, not allanthocyanin-rich sources exerted the same inhibitory effect, with chokeberryextract being the most potent inhibitor. These results suggest that the chemopro-tective effects of anthocyanins depend on their chemical structure.79

Different species and varieties of berries show various potent biologicalactivities. Bilberry extract was found to be more effective in inhibiting thegrowth of human promyelocytic leukemia cell line (HL60) and human col-orectal carcinoma cell line (HCT116), while inducing apoptosis.80 Anthocy-anin fractions obtained from blueberry cultivars showed inhibitory effectson human colorectal carcinoma cell lines (HT-29 and Caco-2)81 higher thanany other fraction obtained from the same berry.80,81

Anthocyanidins have been found to have greater antiproliferation orapoptosis effects than their corresponding glycosylated anthocyanins. How-ever, this may be different with the exploration of various cell lines andmechanisms of action.83–86

The chemoprotective effects of anthocyanin-rich sources have beenmostly associated with tissues of the gastrointestinal tract rather than othersites in in vivo studies.89–95 It has been suggested that the low bioavailabilityand higher anthocyanin concentrations in the gastrointestinal tract may havecaused these differences.96 Freeze-dried black raspberries have been foundto significantly reduce tumor formation in the oral cavities of male Syriangolden hamsters.89 Freeze-dried strawberries and black raspberries havebeen found to significantly decrease O6-methylguanine adducts and inhibitchemically induced esophageal tumors in F-344 rats in pre- or postinitiationstudies,90–92 it has been suggested that they may potentially inhibit bothinitiation and promotion/progression during N-nitrosomethylbenzylamine(NMBA)-induced esophageal tumorigenesis.

4.4.3 Cardiovascular diseases

Current research shows that phenolics and related polyphenolic compoundsinhibit the in vitro and in vivo oxidation of LDL by donation of hydrogen tofree radicals with the formation of stable intermediates.97 Elevation of LDL



levels in plasma has been associated with atherosclerosis.98–100 Anthocyanin-rich berry extracts have been found to exert protection of LDL againstoxidation in vitro. The extracts also protect LDL from hydrogen peroxide-induced oxidative stress in human endothelial cell cultures.61,101,102

4.4.4 Other health benefits of anthocyanins

Many other health benefits have been associated with the consumption ofberries. In most cases, anthocyanin-rich products and extracts seem to havean added benefit. For example, blackberries, elderberries, and strawberries(Fragaria × ananassa Duch. cv. Honeoye) have been shown to selectivelyinhibit cyclooxygenase-2 (COX-2), thus they have potential as pain relieversfor arthritis and gout-related pain.103 Anthocyanins inhibit 2-glucosidaseactivity, thus reducing blood glucose levels, which is a clinical therapy targetfor controlling type II diabetes and obesity.104 Consumption of bilberries hasalso been associated with eye health by improving night vision105 and in thetreatment of glaucoma and retinopathy,106,107 while freeze-dried blueberriesand bilberries have been shown to improve short-term memory in rats.108

4.4.5 Bioavailability

Systemic bioavailability of anthocyanins is generally poor, between 0.02%and 1.80% of the ingested amounts.109–111 Anthocyanins have been found inplasma and urine as both intact glycosylated pigments as well as anthocy-anin metabolites, including glucuronides, methylated derivatives, and sul-foconjugated derivatives. This is significant because most other glycosylatedphenolics are not found in their intact glycosylated forms in plasma. Incontrast, comparatively large concentrations of anthocyanins can be foundin feces after dietary intake of an anthocyanin-rich diet.96,112 Furthermore,the chemoprotective effects of anthocyanins on colon cancer using a ratmodel system have been correlated with the anthocyanin content of the fecesrather than with the anthocyanin content of the urine, suggesting that directinteraction of these compounds with tissues lining the gastrointestinal tractis significant.96

Absorption and excretion of anthocyanins from berry extracts are influ-enced by the conjugated sugar’s structure, especially for a single glucosemoiety.109 Anthocyanins with either a di- or trisaccharide moiety wereexcreted in the urine primarily as their intact form in higher percentage ofingested doses, rather than intact forms of monoglycoside,112 which can bepartially explained by a larger proportion of the anthocyanins with rutino-sides as opposed to the glucosides absorbed in the blood stream.113

Anthocyanins can be metabolized via methylation, glucuronidation, andsulfoconjugation after absorption. Anthocyanins with different aglyconeswere found to be metabolized differently in humans.110–112,114,115

Metabolism by intestinal microflora and transformation of pure antho-cyanin extracts from radish, along with the assumed degradation of the prod-ucts, were evaluated in models to mimic in vivo conditions.116 Glycosylated and



acylated anthocyanins are rapidly degraded by intestinal microflora afteranaerobic incubation with a human fecal suspension.96 The hydroxycinnamates,and conjugated and free ferulic, isoferulic, p-coumaric, sinapic, and vanillicacids were identified in the plasma and urine after consumption of blackcurrant juice.117

The reasons for low bioavailability of anthocyanins are not yet under-stood. One possible explanation is the fact that anthocyanins are not effi-ciently hydrolyzed by β-glucosidase in the gastrointestinal tract, thus causinglow absorption in the bloodstream.118 Another explanation hints at the deg-radation of anthocyanins due to neutral and mild alkaline conditions in theintestines. Food ingredients such as protein and fat have proved to enhanceanthocyanin stability in milk’s matrices, suggesting that these food compo-nents may protect anthocyanins from degradation in vivo.119

4.5 Health benefits of other pigments in berriesBerries such as the sea buckthorn and green currant are rich in flavonols(Table 4.3), especially quercetin, which are good antioxidants.120 Quercetin alsoinhibits cell proliferation in human carcinoma cell lines (HT29 and Caco-2),121

induces apoptosis and differentiation programs in human leukemia cells(K562),122 inhibits angiogenesis and immune-endothelial cell adhesion,123 andsuppresses both DMBA- and N-nitrosomethylurea-induced mammary tum-origenesis in female rats124 and N-nitrosodiethylamine-induced lung tumori-genesis in mice.125 Increased intake resulted in a decrease in cardiovasculardisease mortality.126

Frequent intake of berry juice or cranberry-lingonberry juice is associatedwith the low risk of urinary tract infections in women.127,128 Cranberry juiceor concentrates show protective effects in urinary tract health.129–131 Althoughclinical trials suggest that cranberry juice or cranberry tablets do have someprotective effect,132,133 negative results have been obtained in other studies.134

The proanthocyanidins in cranberries appear to be responsible for the pro-tective effects in the urinary tract by preventing adherence of p-fimbriatedEscherichia coli to the uroepithelial cells.130,131 The proanthocyanidin fractionfrom the pomace extract of sea buckthorn is responsible for the total antiox-idant activity.135 The hydrolyzable tannins fractioned from red raspberriesare major contributors to their antioxidant capacity and also exert a cardio-protective vasodilatory effect in rabbit aorta rings.136 The hydrolysablefractions from raspberries and cloudberries (Rubus chamaemorus) exert anti-microbial activities on the human pathogens staphylococcus and salmonellabacteria.137

Zeaxanthin and lutein are the dietary carotenoids that accumulate in themacular region of the retina and lens, which may in turn reduce age-relatedmacular degeneration (AMD).138,139 Wolfberry (Lycium barbarum) is rich in zeax-anthin (Table 4.3), which is traditionally used as a medicine for vision healthin Asia. Autumn olive berries contain the greatest amount of lycopene, whichreduced the risk of cardiovascular diseases140,141 and prostate cancer.141,142



4.6 Potential application of berry pigments4.6.1 Berry pigment profiles as fingerprints for authenticity

Given the unique and characteristic anthocyanin composition of many ber-ries, the HPLC profile of anthocyanin pigments has been used to monitorthe authenticity of berry juices and other berry products. The use of materialto enhance color represents adulteration unless properly labeled (coloradded). The presence of these pigments may be detected as additional peakson a chromatogram, therefore monitoring the anthocyanin composition ofjuices and other berry products may not only reveal the addition of adulter-ants, but in some cases can indicate the type of adulterant. For example,cranberry juice may be adulterated with a less expensive grape anthocyaninextract. This can be detected by the presence of delphinidin, petunidin, ormalvidin glucosides.143,144 Similarly adulteration of blackberry juice with redraspberries has been reported and is detected by monitoring individualanthocyanins using HPLC.145 Detection of cyanidin 3-sophoroside and cya-nidin 3-xylosyl-rutinoside in blackberry juice might be indicative of adulter-ation with a different plant material. Clearly a limitation of the analysis ofanthocyanins to monitor authenticity is that this analysis applies only toanthocyanin-containing juices, which is the case for most berries. Adultera-tion of a premium juice with a lower cost sweetener or juice is likely toinclude an anthocyanin-containing colorant or juice in order to meet thecolor expectations of consumers.

4.6.2 Berry pigments as natural colorants and value-added ingredients

With consumers more interested in healthier lifestyles, the food industry issearching for natural alternatives to the use of synthetic dyes. Europeaccounts for nearly 50% of global natural colorant sales, the Americanmarket accounts for about 30%, and Japan accounts for about 20%.146 In theUnited States, FD&C Red No. 40, a certified dye, has the highest per capitaconsumption. Although grape is the only berry source listed among the foodcolors exempt from certification (regulated by the U.S. Food and DrugAdministration [FDA] in 21 CFR 73.170 and 21 CFR 73.169), many berriessuch as cranberry, elderberry, chokeberry, bilberry, blueberry, and red rasp-berry can be used to provide color in the form of a juice concentrate andcontribute to a pleasant flavor. The raw materials most suitable for pigmentproduction are the residues of pomace that remain after juice extraction.Different countries have various restrictions in the regulatory aspects ofcolorants in foods. The European Union allows anthocyanins as colorantsand lists them by their E-number (E163). Berry concentrates are consideredto be ingredients and are not listed as colorants. In the United States, fruitand vegetable juice concentrates are among the approved colorants exemptfrom certification (regulated by the FDA in 21 CFR 73.250 and 21 CFR 73.260).However, only physical means of extraction and concentration of the



pigments are allowed, using water as the extracting solvent, in order to fitinto the juice concentrate category. Therefore a berry concentrate used as acolorant would be listed on the label as a colorant.

The optimum conditions for anthocyanin color and stability in foodapplications require low pH. With increases in pH and a consequent decreasein acidity, the protonation of the anthocyanin molecule is lost and chemicaltransformations occur, resulting in a loss of color and stability. In additionto pH sensitivity, anthocyanins are susceptible to degradation by light, heat,oxygen, hydrogen peroxide, iron, copper, and ascorbic acid.147

Anthocyanin colorants have been suggested for beverages, which rep-resents the largest market for commercial applications in the United States.Berry powders and concentrates are recommended for jellies, jams, pre-serves, ice cream, yogurt, gelatin desserts, fruit sauces, candy and confec-tions, chews, bakery fillings, toppings, and pastries.148–150

There is also a large market for functional foods or nutraceuticals, asconsumers are interested in foods that may help prevent or reduce theincidence of illness. The market value of anthocyanin-containing commod-ities is presently valued at several billion dollars. The market value of straw-berries alone for the year 2000 was $1,013,537,000, while the market valueof blueberries was $220,883,000.151 Optimizing health and performancethrough the diet is one of the largest and most lucrative markets in the UnitedStates. A number of studies point out a relationship between consumptionof anthocyanin-rich berries and improved health. Berries have been provento have high antioxidant power21,67,63,66 and may prevent or delay the onsetof major degenerative diseases of aging, including cancer,79,89–91,152 cardiovas-cular diseases,61,102,153 obesity and diabetes,104 cognitive dysfunction,108,154

immune system dysfunction,155 and night blindness.105 Thus anthocyanin-rich berry extracts and concentrates are suggested for value-added functionalfoods in a variety of food applications, such as chews and beverages.149,150

Berry extracts and concentrates are value-added ingredients that are usefulfor functional beverages, bars, candies, and other foods that claim to havehigh ORAC values, enhance the immune system, and reduce the physicaleffects of stress derived from exercise or extreme work conditions.150

Anthocyanin-rich berry extracts and concentrates are also being com-mercialized as dietary supplements. Bilberry dietary supplements areintended to provide nutritive support for normal, healthy eyes and circula-tion.156 Blueberry dietary supplements maintain a healthy urinary tract andenhance brain function.157 Cranberry supplements contain concentratedcranberry juice in a capsulated form, which is commonly recommended toprevent urinary tract infections.156,157 Elderberry capsules are suggested topromote immune system function,156 which helps the body fight and recoverfrom common colds and the flu.

A 100% organic cranberry powder made from whole cranberries withoutcarriers that is certified by the U.S. Department of Agriculture (USDA) andNational Organic Program (NOP) was introduced in 2005. The applicationsof cranberry powder include nutritional supplements, cranberry-enriched



sports drinks, fortified nutrition bars, dental hygiene products, healthysnacks, weight management products, and cosmetics.149

Thus berry extracts and concentrates rich in anthocyanins can bevalue-added ingredients for a variety of functional foods and nutraceuticalsto meet the increasing demand of consumers for a healthy lifestyle.

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175. Liu, M., Li, X.Q., Weber, C., Lee, C.Y., Brown, J., and Liu, R.H, Antioxidantand antiproliferative activities of raspberries, J. Agric. Food Chem., 50, 2926,2002.

176. Burrows, C. and Moore, P.P., Genotype × environment effects on raspberryfruit quality, Acta Hort. (ISHS), 585, 467, 2002.

177. McGhie, T.K., Hall, H.K., Ainge, G.D., and Mowat, A.D., Breeding Rubuscultivars for high anthocyanin content and high antioxidant capacity, ActaHort. (ISHS), 585, 495, 2002.


179. Clark, J.R., Howard, L., and Talcott, S., Antioxidant activity of blackberrygenotypes, Acta Hort. (ISHS), 585, 475, 2002.



180. Perkins-Veazie, P. and Kalt, W., Postharvest storage of blackberry fruit doesnot increase antioxidant levels, Acta Hort. (ISHS), 585, 521, 2002.

181. Inami, O., Tamura, I., Kikuzaki, H., and Nakatani, N, Stability of anthocyaninsof Sambucus canadensis and Sambucus nigra, J. Agric. Food Chem., 44, 3090, 1996.

182. Wu, X. and Prior, R.L., Systematic identification and characterization ofanthocyanins by HPLC-ESI-MS/MS in common foods in the United States:fruits and berries, J. Agric. Food Chem., 53, 2589, 2005.

183. Nickavar, B. and Amin, G., Anthocyanins from Vaccinium arctostaphylos ber-ries, Pharm. Biol., 42, 289, 2004.

184. Cho, M.J., Howard, L., Prior, R., and Clark, J., Flavonoid glycosides andantioxidant capacity of various blackberry, blueberry and red grape geno-types determined by high-performance liquid chromatography/mass spec-trometry, J. Sci. Food Agric., 84, 1771, 2004.

185. Dugo, P., Mondello, L., Errante, G., Zappia, G., and Dugo, G., Identificationof anthocyanins in berries by narrow-bore high-performance liquid chroma-tography with electrospray ionization detection, J. Agric. Food Chem., 49, 3987,2001.

186. Andersen, O.M., Chromatographic separation of anthocyanins in cowberry(lingonberry) Vaccinium vites-idaea L, J. Food Sci., 50, 1230, 1985.

187. Slimestad, R. and Solheim, H., Anthocyanins from black currants (Ribesnigrum L.), J. Agric. Food Chem., 50, 3228, 2002.

188. Goiffon, J.P., Brun, M., and Bourrier, M.J., High-performance liquid chroma-tography of red fruit anthocyanins, J. Chromatogr., 537, 101, 1991.

189. Longo, L. and Vasapollo, G., Anthocyanins from bay (Laurus nobilis L.) berries,J. Agric. Food Chem., 53, 8063, 2005.

190. Longo, L., Vasapollo, G., and Rescio, L., Identification of anthocyanins inRhamnus alaternus L. berries, J. Agric. Food Chem., 53, 1723, 2005.

191. Oszmianski, J. and Sapis, J.C., Anthocyanins in fruits of Aronia melanocarpa(chokeberry), J. Food Sci., 53, 1241, 1988.

192. Lopes-da-Silva, F., de Pascual-Teresa, S., Rivas-Gonzalo, J., and Santos-Buelga,C., Identification of anthocyanin pigments in strawberry (cv. Camarosa) byLC using DAD and ESI-MS detection, Eur. Food Res. Technol., 214, 248, 2002.

193. Maatta-Riihinen, K.R., Kamal-Eldin, A., and Torronen, A.R., Identification andquantification of phenolic compounds in berries of Fragaria and Rubus species(family Rosaceae), J. Agric. Food Chem., 52, 6178, 2004.

194. Fiorini, M., Preparative high-performance liquid chromatography for the pu-rification of natural anthocyanins, J. Chromatogr. A, 692, 213, 1995.

195. Mullen, W., Lean, M.E., and Crozier, A., Rapid characterization of anthocy-anins in red raspberry fruit by high-performance liquid chromatographycoupled to single quadrupole mass spectrometry, J. Chromatogr. A, 966, 63,2002.

196. Tian, Q., Giusti, M.M., Stoner, G.D., and Schwartz, S.J., Characterization of anew anthocyanin in black raspberries (Rubus occidentalis) by liquid chroma-tography electrospray ionization tandem mass spectrometry, Food Chem.,94, 465, 2006.

197. Bonora, A., Pancaldi, S., Gualandri, R., and Fasulo, M.P., Carotenoid andultrastructure variations in plastids of Arum italicum Miller fruit duringmaturation and ripening, J. Exp. Bot., 51, 873, 2000.

198. Hakkinen, S.H., Karenlampi, S.O., Heinonen, I.M., Mykkanen, H.M., andTorronen, A.R., Content of the flavonols quercetin, myricetin, and kaempferolin 25 edible berries, J. Agric. Food Chem., 47, 2274, 1999.



199. Goldmann, W.H., Sharma, A.L., Currier, S.J., Johnston, P.D., Rana, A., andSharma, C.P., Saw palmetto berry extract inhibits cell growth and Cox-2expression in prostatic cancer cells, Cell Biol. Int., 25, 1117, 2001.

200. Olsson, M.E., Gustavsson, K.E., Andersson, S., Nilsson, A., and Duan, R.D.,Inhibition of cancer cell proliferation in vitro by fruit and berry extracts andcorrelations with antioxidant levels, J. Agric. Food Chem., 52, 7264, 2004.

201. Sun, J., Chu, Y.F., Wu, X., and Liu, R.H., Antioxidant and antiproliferativeactivities of common fruits, J. Agric. Food Chem., 50, 7449, 2002.

202. Seeram, N.P., Adams, L.S., Hardy, M.L., and Heber, D., Total cranberry extractversus its phytochemical constituents: antiproliferative and synergistic effectsagainst human tumor cell lines, J. Agric. Food Chem., 52, 2512, 2004.


147

chapter 5

Antioxidant capacity and phenolic content of berry fruits as affected by genotype, preharvest conditions, maturity, and postharvest handling

Shiow Y. Wang

Contents

5.1 Introduction ................................................................................................1485.2 Effect of variety and genotype ................................................................152

5.2.1 Phenolic content as affected by variety and genotype ...........1525.2.1.1 Strawberries (

Fragaria

) ...................................................1525.2.1.2

Vaccinium

..........................................................................1545.2.1.3

Rubus, Ribes, Aronia, Sambucus

, and

Sorbus

........................................................................1565.2.2 Antioxidant capacity affected by varieties

and genotypes................................................................................1595.2.2.1 Strawberries (

Fragaria

) ...................................................1605.2.2.2

Vaccinium

..........................................................................1615.2.2.3

Rubus

.................................................................................1625.2.2.4

Ribes

...................................................................................1635.2.2.5

Aronia, Sambucus

, and

Sorbus

........................................163



5.3 Production environment and growing season......................................1645.3.1 Growing region..............................................................................1645.3.2 Growing season .............................................................................1655.3.3 Cultivation techniques .................................................................165

5.4 Maturity.......................................................................................................1675.5 Postharvest handling.................................................................................169

5.5.1 Storage conditions.........................................................................1705.5.2 Controlled atmospheres ...............................................................1715.5.3 Other postharvest treatments......................................................173

5.5 Conclusion...................................................................................................175References.............................................................................................................178

5.1 Introduction

Epidemiological studies have consistently shown that eating more fruits andvegetables can aid in preventing stomach, lung, mouth, esophagus, colon,and rectal cancers and other age-related diseases.

1

The incidence of otherchronic diseases, such as coronary heart disease, atherosclerosis, and stroke,may also be reduced through increased fruit and vegetable consumption.

2,3

This can be attributed to the high content of phytonutrients, such as fla-vonoids, carotenoids, vitamins, phenols, dietary glutathionine, and endog-enous metabolites, in fruits and vegetables.

Berry fruits constitute one of the important sources of potential health-promoting phytochemicals. These fruits are rich sources of phenolic com-pounds. The most important group of phenolics in berry fruits is theflavonoids, which consist mainly of flavonols, anthocyanidins, proanthocya-nidins, catechins, flavons, and their glycosides. Flavonoids, or bioflavonoids,are a ubiquitous group of naturally occurring benzo-pyrone derivatives. Theyrepresent a large family of low molecular weight polyphenolic secondarymetabolites that are widespread throughout the plant kingdom, and they forman integral part of the human diet.

4

More than 6000 different flavonoids havebeen described and the number is still increasing.

5

They all share the samebasic skeleton, the flavan nucleus, consisting of two aromatic rings (ring Aand B) with six carbon atoms interconnected by a hetero cycle including threecarbon atoms (ring C). According to modifications of the central C ring, theycan be divided into different structural classes such as flavanones, isoflavones,flavones, flavonols, flavanols, and anthocyanins. The huge diversity in fla-vonoid structures is due to modifications of the basic skeleton by enzymessuch as glycosyl transferases, methyl transferases, and acyl transferases.

5,6

Ina single plant species, dozens of different flavonoids may be present and mostof these are conjugated to various sugar moieties.

6

Many studies have suggested that flavonoids exhibit biological activities,including antiallergenic, antiviral, anti-inflammatory, and vasodilatingactions. Flavonoids have been shown to modify eicosanoid biosynthesis,

7

prevent platelet aggregation,

8,9

and promote relaxation of cardiovascularsmooth muscle.

10,11

In addition, flavonoids and related polyphenolics have


Chapter 5: Antioxidant capacity and phenolic content of berry fruits 149

a great potential to delay low-density lipoprotein (LDL) oxidation

12,13

andprotect against atherosclerosis by inhibiting the accumulation of oxidizedLDL in atherosclerotic lesions.

14

This observation implies that flavonoidsconfer protection against early events in atherogenic lesion formation. Fla-vonoids may work alone as well as in conjunction with vitamins and othernutrients to stimulate protective enzymes or to block various hormonalactions and metabolic pathways that are associated with the developmentof cancer and heart disease.

3,15,16

Acidic compounds incorporating phenolic groups have been repeatedlyimplicated as active antioxidants. Phenolic acids such as caffeic acid, chlo-rogenic acid,

p

-coumaric acid, and vanillic acid are widely distributed inberry crops as natural antioxidants. Their antioxidant activities are associatedto some extent with the number of hydroxyl groups in their molecularstructure.

17

It is likely that dihydroxylation in the 3,4 position may enhanceantioxidant potency by making more available hydrogen donors. Chloro-genic acid, a phenolic derivative, has been found to be the most abundantphenolic acid in berry fruit extracts and also the most active antioxidant.Chlorogenic acid (1.2

×

10

5

M) inhibited more than 80% of peroxide formationin a linoleic acid test system.

18

Other phenolic derivatives such as benzoicacid, caffeic acid, catechol,

p

-cresol, gallic acid, rutin, and vanillic acid occurwidely in berry fruits and a significant quantity is consumed in our dailydiet. They are high in antioxidant activity and act as natural antimicrobialagents.

19

Flavonols such as

p

-coumaroyl glucose, dihydroflavonol, quercetin 3-glu-coside, quercetin 3-glucuronide, kaempferol 3-glucoside, and kaempferol3-glucuronide have been detected in berry fruits. These flavonols serve aseffective antioxidants by reacting with free radicals and thus interrupting thepropagation of new free radicals, or by chelating metal ions which catalyzelipid oxidation to alter their reduction-oxidation (redox) potentials.

20–24

Fla-vonols have structures that allow them to have more effective antioxidantactivity than anthocyanins. The 2,3 double bond in conjunction with a 4-oxofunction in the C ring of quercetin allows electron delocalization from theB ring, shows extensive resonance, and results in significant effectiveness forradical scavenging.

17

Quercetin has a structure similar to that of cyanidin inthe A and B rings (3,4-dihydroxy substituents in the B ring and conjugationbetween the A and B rings) and the same number and arrangement of fivehydroxyl groups. This suggests that quercetin may contribute significantly toantioxidant potential because its structure effectively satisfies the stabilizationof the aryloxyl radical after hydrogen donation. An additional OH group atthe B ring 5

′

position of quercetin, as in myricetin, increases the oxygen radicalabsorbance capacity (ORAC). Wang et al.

25

also reported that the antioxidantactivity of myricetin was higher than that of quercetin in terms of the ORACvalue. Kaempferol, with a structure related to that of quercetin, but with onlya single 4

′

-OH group in the B ring, has just 27% of quercetin’s antioxidantactivity. Quercetin and kaempferol are potent quenchers of ROO, O

2

, and

1

O

2

.

18

Quercetin and other polyphenols have been shown to play a protective role



in carcinogenesis by reducing the bioavailability of carcinogens. They havealso demonstrated significant anti-inflammatory activity due to direct inhibi-tion of several initial processes of inflammation.

26

Anthocyanins are potent flavonoid antioxidants widely distributed inberry fruits. They have received attention as important dietary constituentsthat may provide health benefits and contribute antioxidant capacity beyondthose provided by essential micronutrients such as ascorbate and toco-pherols. The anthocyanins are glycosides and acylglycosides of anthocyani-dins. They not only have a very low first oxidation potential, but they alsoshow more than one oxidation wave. This low oxidation potential rendersthem into prooxidants by redox cycling.

27

Some common anthocyanidinshave varying hydroxyl or methyl substitutions in their basic structure, fla-vylium. More than 250 naturally occurring anthocyanins exist and are dif-ferentiated further by their

o

-

glycosylation with different sugar substitutes.

28

Glucose, rhamnose, xylose, galactose, arabinose, and fructose are the mostcommon sugars substituted on the aglycon (anthocyanidin). The commonanthocyanins are either 3- or 3,5-glycosylated. Free radical scavenging prop-erties of the phenolic hydroxy groups attached to ring structures are respon-sible for the strong antioxidant properties of the anthocyanins.

17,25

Berry fruits in particular have a high anthocyanins content. Anthocya-nins have been used for several therapeutic purposes, including the treat-ment of diabetic retinopathy, fibrocystic disease, and vision disorders.

29,30

Anthocyanins also have the potential to serve as radiation-protective agents,vasotonic agents, and chemoprotective agents, and can act against carbontetrachloride-induced lipoperoxidation.

25

Anthocyanins also decrease thefragility of capillaries, inhibit blood platelet aggregation and LDL oxidation,facilitate endothelium-dependent vasodilation of arteries, and strengthen thecollagen matrix, which is the protein component of connective tissues.

31

Proanthocyanidins are polyflavonoid in nature, consisting of chains of fla-van-3-ol units. They are widely distributed in berry fruits.

20

Proanthocyanidinshave relatively high molecular weights and have the ability to bind strongly withcarbohydrates and proteins. Proanthocyanidins are strong free radical scavengersand are believed to be at least 15 to 25 times stronger than the powerful antioxidantvitamin E and have demonstrated a wide range of pharmacological activity.

32,33

Catechin is a powerful, water-soluble polyphenol antioxidant that iseasily oxidized; several thousand types are available in the plant world andare believed to have some value in fighting tumors as well as enhancingimmune system function.

33

These phytochemicals have exhibited additiveand synergistic effects on antioxidant activity when they are included in themixture conditions. Recent research also indicates better health functionalityof whole foods compared to single active compounds, suggesting a syner-gistic interaction of phenolic phytochemicals in the diet.

34,35

Therefore thefunctionality of whole foods can be further improved by enriching themwith functional phenolic phytochemicals to promote synergistic activity.

Berry fruits have a high phenolic content and antioxidant properties.The structures of the major phenolics in berry fruits are listed in Figure 5.1.



Figu

re 5

.1

The

str

uctu

res

of t

he m

ajor

phe

nolic

s in

ber

ry f

ruit

s.

R2

R1

OH

OH

OO

H

OH

+

A

B

C2

34

5

6

78

2'

3'

4' 5'

6'

O O

R1

R2

OH

OH

OH

OH

CO

OH

R1

OH

CH

3O

HO

CO

OH

CO

OH

O

HO

HO

HO

OH

CO OH

R1=

OH

R2=

H:C

yani

din

R1=

OH

R2=

OH

:Del

phin

idin

R1=

OC

H3

R2=

OH

:Pet

unid

inR

1=O

CH

3R

2=O

CH

3: M

alvi

din

R1=

OC

H3

R2=

H:P

eoni

din

R1=

HR

2=

OH

:Que

rcet

inR

1=

HR

2=

H:K

aem

pfer

olR

1=

OH

R2=

OH

:Myr

ice t

in

R1=

OH

:Caf

feic

acid

Van

illic

acid

Chl

orog

enic

acid

R1=

H:p

-Cou

mar

icac

idR

1=O

CH

3:F

erul

icac

idElla

gic

acid

Cat

echi

n

Proc

yani

din

Oli

gom

ers

n=0-

13



The phenolic content and antioxidant capacity in berries are affected bygenetic differences (genotypes), the degree of maturity at harvest, preharvestenvironmental conditions, and postharvest treatment and storage condi-tions. This chapter discusses the effects of all of these factors on antioxidantcapacity and phenolic content of berry fruits.

5.2 Effect of variety and genotype

Genetic factors such as variety and genotype play an important role in berryfruit composition. It is well known that the phenolic content and antioxidantcapacity of berry fruit are influenced by variations among cultivars. Thereare wide differences in the antioxidant content and activity among variousvarieties of the genus

Fragaria

,

Vaccinium

,

Ribes

,

Rubus

,

Aronia

,

Sambucus

, and

Sorbus

. Since each genotype has a distinct composition, breeding forimproved quality, including high phenolic content and antioxidant capacity,has been an important part of cultivar improvement programs.

5.2.1 Phenolic content as affected by variety and genotype

5.2.1.1 Strawberries (

Fragaria

species)

Strawberries have a highly desirable taste and flavor and are one of the mostpopular edible fruits. The cultivated strawberry (

Fragaria

ananassa

) is a hybridof two wild species. One was from Chile (

Fragaria

chiloensis

) and the otherfrom Virginia (

Fragaria

virginiana

). The Chilean strawberry grows vigorouslyand was selected as the female plant for breeding. The

virginiana

strawberryis popular for its sweet flavorful scarlet fruit and is a successful pollinator of

F

.

chiloensis

. The hybrid is called

F

.

ananassa

, which we grow today.

5.2.1.1.1 Phenolic acids in strawberries. p

-Coumaric acid and ellagicacid are the two predominant phenolic acids in strawberries. The

p

-coumaricacid content varies greatly among cultivars, from 0.9 (Korona) to 4.1 (Honeoye)mg/100 g fresh weight (FW).

36

Ellagic acid occurs in particularly high concentrations in strawberries,with concentrations approximately three times that of other fruits and nuts.

37

However, published authors have differed on whether ellagic acid is the mainphenolic compound in strawberries.

38-40

The amount of ellagic acid found inthe ripe fruit of strawberry genotypes ranges from 0.22 to 46.5 mg/100 gFW.

36,41–43

Maas et al.

44

reported the total ellagic acid content of red pulp for35 cultivars, ranging from 43 to 464 mg/100 g dry weight (DW). Cordenunsiet al.

40

found that in six cultivars of strawberries, free ellagic acid ranged from0.9 to 1.9 mg/100 g FW, which was similar to the values reported by Gil et al.

22

and Amakura et al.

45

Most of the ellagic acid in strawberries is present as anellagitannin esterified with glucose, requiring an acid hydrolysis step toliberate it.

46

Kähkönen et al.

32

found that ellagitannin content varied amongdifferent cultivars, ranging from 81 to 184 mg/100 g DW. The differences inellagic acid content tend to be heritable characteristics of each cultivar.



5.2.1.1.2 Flavonols and flavan-3-ols in strawberries.

In fresh, ripe straw-berry cultivars, various authors have reported the concentration of quercetinas ranging from 0.3 to 5.3 mg/100 g FW, kaempferol content ranging fromundetectable to 0.9 mg/100 g FW, and myricetin at approximately 100 mg/100 g FW.

32,47–49

Total phenolic content in strawberries has been reported to range from42 to 289 mg/100 g FW.

36,40

The presence of quercetin and kaempferol glu-cosides and glucoronides in strawberries has also been reported.

22

Wang andLewers (unpublished data) found total phenolic levels ranging from 123.24to 275.29 mg/100 g FW among 19 genotypes in two growing seasons. Thecontent of

p

-coumaroylglucose, quercetin 3-glucoside, and quercetin 3-glu-curonide also varied substantially among the genotypes. In general, thecontent of quercetin 3-glucoside and quercetin 3-glucuronide was signifi-cantly higher than other flavonols, such as kaempferol 3-glucoside andkaempferol 3-glucuronide.

F. virginiana

had a higher content of quercetin3-glucoside and quercetin 3-glucuronide than

F. ananassa

and

F. chiloensis

(Wang, S.Y. and Lewers, K., unpublished data).

5.2.1.1.3 Anthocyanins in strawberries.

Strawberry fruit contains fourmajor anthocyanins (cyanidin 3-glucoside, pelargonidin 3-glucoside, cyani-din 3-glucoside-succinate, and pelargonidin 3-glucoside-succinate) that varysignificantly in content among genotypes.

42,50

Sondheimer and Karash

51

showed that the major pigments of wild strawberries (

Fragaria vesca

) arepelargonidin 3-glucoside and cyanidin 3-glucoside. The amount of pelar-gonidin-3-glucoside was about 20 times more than cyanidin-3-glucoside instrawberry genotypes.

41,42

Garcia-Viguera et al.

52

reported the amount ofpelargonidin-3-glucoside and cyanidin-3-glucoside as 65.20 to 72.61 mg/100 gFW and 6.64 to 7.39 mg/100 g FW, respectively.

Wang and Lewers (unpublished data) found that cyanidin 3-gluco-side levels ranged from 16.29 to 220.75

µ

g/g FW among 19 genotypes intwo growing seasons, with the lowest in Allstar and the highest in NC95-19-1. Pelargonidin 3-glucoside levels ranged from a low of 161.82

µ

g/g FW in 2 TAP 4B to a high of 813.44

µ

g/g FW in NC96-53. The ratiosof pelargonidin 3-glucoside to cyanidin 3-glucoside ranged from 1.53 to22.19 for various strawberry cultivars, selections, and wild strawberries.Allstar had the highest ratio of pelargonidin 3-glucoside to cyanidin3-glucoside, whereas CFRA 0368 had the lowest ratio. The species of

F

.

ananassa

had higher ratios of pelargonidin 3-glucoside to cyanidin 3-glucoside compared to

F. chiloensis

and

F. virginiana

. Although the anti-oxidant activity of cyanidin 3-glucoside was much higher than that ofpelargonidin 3-glucoside, the antioxidant activities did not show anycorrelation to cyanidin content (

R

2

=

0.2362) or the ratios of pelargonidin3-glucoside to cyanidin 3-glucoside in strawberries (

R

2

=

0.1812).

53

Thisis probably because the total antioxidant activity is derived from thecomplex mixture of phytochemicals in the strawberry fruit, which act inan additive and synergistic manner.



Anthocyanin levels varied significantly among different strawberry cul-tivars. Cordenunsi et al.

40

found that the amount of anthocyanin in sixstrawberry cultivars (Toyonoka, Pajaro, Mazi, Dover, Campineiro, and OsoGrande) ranged from 13 to 55 mg/100 g FW. These values are comparablewith other cultivars described in the literature, such as Chandler (80 mg/100 g FW)

54

and Red Gauntlet (30 mg/100 g FW).

55

The cultivars of Mazi,Oso Grande, and Dover contained twice as much anthocyanin compared toPajaro, Toyonoka, and Campineiro at the full-ripe stage.

40

5.2.1.2

Vaccinium

species

Blueberries, bilberries, cranberries, deerberries, lingonberries, huckber-ries, and bog whortleberries belong to the genus

Vaccinium

.

Vaccinium

berries have high antioxidant and anticarcinogenic properties that arepartly due to high levels of flavonoids, including anthocyanins, catechins,and proanthocyanins or flavan-3-ols. Therefore fruit from the

Vaccinium

species may provide beneficial effects in human health and can be animportant part of a healthy diet. Significant variations in antioxidantactivity, total anthocyanins, and total phenolic were observed among thedifferent

Vaccinium

species.

5.2.1.2.1 Phenolic acids in Vaccinium species. Vaccinium species varyin their content of phenolic acids, including caffeic acid, chlorogenic acid,p-coumaric acid, gallic acid, ferulic acid, and p-hydroxybenzoic acid. Sell-appan et al.56 found significant differences among rabbiteye blueberryvarieties (Tifblue and Climax) and southern highbush blueberries withrespect to gallic acid, p-hydroxybenzoic acid, caffeic acid, p-coumaric acid,and ferulic acid.

Chlorogenic acid was found at high levels in lowbush, half-highbush,and highbush blueberry species and Evergreen huckleberry, ranging from50 to 142 mg/100 g FW.57,58 Differing amounts of ferulic acid have beenreported by several authors, from small amounts in Vaccinium species tobeing the major phenolic acid in Northblue and Northcountry blueberriesand in cranberries.38 p-Coumaric acid (8 to 11 mg/kg FW), caffeic acid,and ferulic acid (3 to 6 mg/kg FW) have also been found in bog whortle-berries.59

There is wide genetic variability in lingonberry genotypes with respectto flavonoid and antioxidant content. Amberland contained the highestamounts of caffeic acid (63.4 µg/g FW) and p-coumaric acid (61.6 µg/gFW).60,61 Wang et al. (unpublished data) evaluated fruit from three genotypesof deerberries (B-59, B-76, and SHF3A-3:127) and found caffeic acid rangingfrom 40.6 to 61.2 µg/g FW and p-coumaric acid ranging from 27.7 to 33.1 µg/gFW. The highest amounts of phenolic acids were found in B-76.

5.2.1.2.2 Flavonols and flavan-3-ols in Vaccinium species. Catechin, epi-catechin, myricetin, and quercetin have been detected in Vaccinium species.



Different genotypes contain different amounts of flavonols. In Amberlandlingonberries, Zheng and Wang60 found that quercetin was the mainflavonol (74 to 146 mg/kg FW), kaempferol was present in small amounts,and myricetin was not detected. Among cranberry varieties, quercetinranged from 83 to 250 mg/kg FW, myricetin ranged from 11 to 24 mg/kgFW, and kaempferol ranged from 0 to 3 mg/kg FW.60,62 Bog whortleberries(Vaccinium uliginosum) contained large amounts of quercetin and myricetinand moderate amounts of catechin.36,59

In Georgia-grown blueberries, Sellappan et al.56 reported that catechin wasthe major flavonoid, with concentrations of up to 387.48 mg/100 g FW (rab-biteye blueberries, Austin). Epicatechin was found only in rabbiteye blueber-ries and concentrations ranged from 34 to 129.51 mg/100 g FW, with thehighest concentrations found in Briteblue. The myricetin content in blueberrieshas been reported to range from 2.3 to 10.0 mg/100 g FW.38,56 The highestlevels of quercetin were found in southern highbush blueberry FL 86-19, at14.60 mg/100 g FW, followed by rabbiteye blueberry Climax, at 9.97 mg/100g FW.56 Bilyk and Sapers62 reported that the fruit of four highbush blueberrycultivars (Earliblue, Weymouth, Coville, and Bluetta) contains quercetin (2.4to 2.9 mg/100 g FW). The kaempferol content of rabbiteye blueberries andsouthern highbush blueberries was 3.72 and 3.17 mg/100 g FW, respectively.56

Taruscio et al.58 reported that black huckleberries had the highest levelsof catechins (240 µg/g FW), followed by wild cranberries (176 µg/g FW)and red huckleberries (154 µg/g FW). Wild cranberries and alpine bilberrieshad high quercetin levels (225.9 µg/g FW), and the myricetin content inalpine bilberry species was found to be 5 to 10 times the amounts detectedin other Vaccinium species.58

Lyons et al.63 measured resveratrol, a strong antioxidant with cancerchemopreventive activity, in the fruit of bilberry (Vaccinium myrtillus L.),lowbush “wild” blueberry (Vaccinium angustifolium Aiton), rabbiteye blue-berry (Vaccinium ashei Reade), and highbush blueberry (Vaccinium corymbo-sum L.) and found that the levels of trans-resveratrol in these specimensranged from 140.0 ± 29.9 to 71.0 ± 15.0 pmol/g FW. Rimando et al.64 alsofound resveratrol in lowbush blueberry, sparkleberry, rabbiteye blueberry,highbush blueberry, Elliott’s blueberry, cranberry, bilberry, deerberry,lingonberry, and partridgeberry at levels between 7 and 5884 ng/g DW.Lingonberries were found to have the highest content, at 5884 ng/g DW,which is comparable to that found in grapes, at 6471 ng/g DW. Pterostilbenewas found in two cultivars of V. ashei and in Vaccinium stamineum at levels of99 to 520 ng/g DW. Piceatannol was found in V. corymbosum and V. stamineumat levels of 138 to 422 ng/g DW.

5.1.1.2.3 Anthocyanins in Vaccinium species. Blueberries have beenfound to contain nonacylated glucosides and galactosides of delphinidin,cyanidin, petunidin, peonidin, and malvidin. Total anthocyanins in 11cultivars of blueberries ranged from 110 to 260 mg/100 g FW.57 Sellappan



et al.56 reported the average total anthocyanin content among rabbiteyeblueberries and southern highbush blueberries was 113.55 and 84.12 mg/100 g FW, respectively. Taruscio et al.58 found that oval-leaf blueberriesand Evergreen huckleberries exhibited high levels of total anthocyani-dins, whereas cranberries and red huckleberries exhibited the leastamount.

In general, cyanidin and delphinidin are the primary anthocyanidins inVaccinium species. Malvidin, peonidin, and petunidin also exist in Vacciniumspecies, but to a lesser extent. These observations have been seen inhalf-high and highbush blueberries, alpine bilberries, wild cranberries, andred huckleberries.

In cranberries, Zheng and Wang60 found that peonidin 3-galactosidewas the main anthocyanidin in Ben Lear cranberries, followed by peoni-din 3-arabinoside, cyanidin 3-glucoside, cyanidin 3-galactoside, andpeonidin 3-glucoside. In deerberries, cyanidin 3-galactoside and cyanidin3-arabinoside were the two predominant anthocyanins, followed by cya-nidin 3-galactoside, cyanidin 3-glucoside, cyanidin 3-arabinoside, andpeonidin 3-glucoside (amounts ranging from 32.2 to 987.5 µg/g FW). In12 cultivars of ripe lingonberries, the total anthocyanin content rangedfrom 30.8 to 95.5 mg/100 g FW, with Ammerland having the highest andSanna the lowest content. Cyanidin 3-galactoside was the predominantanthocyanin, contributing the most antioxidant activity in lingonberries.Cyanidin 3-arabinoside and peonidin 3-glucoside were also present inlingonberries.60,61 Määttä-Riihinen et al.59 found bog whortleberries con-tained large amounts of delphinidin (730 to 1661 mg/kg FW) and mal-vidin (863 to 1572 mg/kg FW) and lesser amounts of cyanidin (130 to451 mg/kg FW), petunidin (373 to 879 mg/kg FW), and peonidin (0 to52 mg/kg FW).

5.2.1.3 Rubus, Ribes, Aronia, Sambucus, and Sorbus speciesPhenolic acids, flavonols, anthocyanins, and proanthocyanins are impor-tant polyphenolic components in Rubus, Ribes, Aronia, Sambucus, and Sorbusspecies. There are large variations in the anthocyanin content, phenoliccontent, and antioxidant capacity among these species. Rubus representsone of the most diverse genera of plants and is widely distributed globallyas wild and cultivated species and genotypes. Of the cultivated Rubusspecies, the most popular are blackberry and raspberry. Marion blackber-ries (marionberries), boysenberries, and cloudberries all belong to theRubus genera. Gooseberry and currant are important berries in the generaof Ribes. Chokeberry and elderberry belong to Aronia and Sambucus generaand are used to make juices, jams, pies, wine, and soft drink flavoring.Berries of rowan (Sorbus aucuparia L.) have traditionally been used for jelliesand jams, but their use as a food ingredient has been less popular becauseof their bitter taste.



5.2.1.3.1 Phenolic acids in Rubus, Ribes, Aronia, Aambucus, and Sorbusspecies. Siriwoharn et al.65 reported the total phenolic content of 11 black-berry cultivars, ranging from 6.82 to 10.56 mg/g FW. Among them, ORUSand marionberry had relatively larger amounts. Wada and Ou66 found thatthe phenolic content of Evergreen blackberries, red raspberries, boysenber-ries, and marionberries was similar (4.95 to 5.99 mg/g FW), whereas blackraspberries (9.8 mg/g FW) had higher levels than the other berries. Wadaand Ou66 also found that gallic acid was present in Evergreen blackberries,marionberries, and boysenberries at 0.02, 0.03, and 0.09 mg/g FW, respectively.Rutin was present in all berries except boysenberries, at levels of 0.11 mg/gFW in red raspberries and marionberries, 0.19 mg/g FW in black raspberries,and 0.24 mg/g FW in Evergreen blackberries. Isoquercitrin was found onlyin Evergreen blackberries, at 0.06 mg/g FW. The level of total ellagic acidranged from 47 mg/g FW in red raspberries to 90 mg/g FW in black rasp-berries and the free ellagic acid level was approximately 40% to 50% of thetotal ellagic acid. Raspberries, thornless blackberries (Rubus eubatus), mari-onberries, Evergreen blackberries, and boysenberries have all been found tobe good sources of ellagic acid.67,68

In raspberries, Rommel and Wrolstad67,69 showed that the Willametteand Meeker varieties contain the most ellagic acid and ellagic forms, whereasVeten and Norna contain medium amounts. Cloudberries, red raspberries,and arctic bramble contain larger amounts of ellagic acid than strawberries.38

Chokeberries contain a large amount of ferulic acid, followed by caffeic acidand ellagic acid. p-Coumaric acid (18 mg/kg FW) and caffeic acid (179 mg/kg FW) were detected in elderberries.59 Hydroxycinnamic acids of sweetrowanberries consist mainly of chlorogenic acid (29 to 160 mg/100 g FW)and neochlorogenic acid (34 to 104 mg/g FW). Chlorogenic acid dominatesin certain rowanberry cultivars, whereas neochlorogenic acid dominates inother rowanberry hybrids.70

5.2.1.3.2 Flavonols and flavan-3-ols in Rubus, Ribes, Aronia, Sambucus,and Sorbus species. The levels of total flavonol content in blackberry geno-types were low compared with total anthocyanins, ranging from a low of102.0 mg/kg FW for Chickasaw to a high of 160.2 mg/kg FW for Apache.71

Fruit of 12 thornless blackberry varieties and selections contained variousamounts of quercetin (5 to 35 mg/kg FW) and kaempferol (1 to 3 mg/kgFW), but myricetin was not detected in any of the blackberry genotypes.62

Rommel and Wrolstad67,69 found that there were great differences in theconcentrations of the total quercetin and kaempferol forms among variet-ies, with Heritage, Willamette, and Norna containing the most totalkaempferol forms. The Heritage, Golden, Malling Promise, and Nornacultivars had the highest concentration of quercetin 3-glucuronide. Rasp-berries, cloudberries, and arctic bramble also contained quercetin (6 to 31mg/kg FW), but kaempferol and myricetin were not detectable.38,48 Quercetin



was the main phenolic compound, followed by myricetin and kaempferolin bilberries, gooseberries, red currant, black currant, chokeberries, andcrowberries.38,48

Siriwoharn et al.65 found that there were considerable differences inpolyphenolics among 11 blackberry cultivars. The procyanidin concentrationranged from 3.29 to 27.2 mg/100 g FW, ellagitannins ranged from 7.77 to27.2 mg/100 g FW, flavonols ranged from 4.06 to 11.9 mg/100 g FW, andellagic acid derivatives ranged from 0.46 to 1.63 mg/100 g FW. Evergreenand Waldo had the highest flavonol and procyanidin concentrations, whereasORUS was highest in both ellagitannins and ellagic acid derivatives. GlenAmple raspberries contained significant quantities of the ellagitannin san-guiin H-6, along with lower levels of a second ellagitannin, lambertianin C.Raspberries also contain a wide variety of quercetin- and kaempferol-basedflavonol conjugates, with the major components being quercetin-3-glucuronideand quercetin-3-glucoside.67,69,72 In addition, raspberry juice was reported tocontain catechins.73 In chokeberries, quercetin was also the main phenoliccompound. Quercetin 3-galactoside and quercetin 3-glucoside were the twomajor flavonols in chokeberries, while the main flavonols in lingonberrieswere quercetin 3-galactoside, quercetin 3-arabinoside, and quercetin3-rhamnoside,60 and in elderberries only quercetin was detected (331 mg/kgFW).59 Flavonol content in the sweet rowanberries varied from 16 to 36 mg/100 g FW; quercetin and two kaempferol glycosides were the major flavonols.Määttä-Riihinen et al.59 detected quercetin derivatives (11.9 mg/100 g FW) butonly traces of kaempferol in sweet rowanberry cv. Granatnaja.70

5.2.1.3.3 Anthocyanins in Rubus, Ribes, Aronia, Sambucus, and Sorbusspecies. Wada and Ou66 found that black raspberries have high levels ofanthocyanins, at 5.89 mg/g FW. The anthocyanin content of the other Rubusspecies ranged from 0.65 mg/g FW in red raspberries to 1.55 mg/g FW inmarionberries. Cho et al.71 reported the total anthocyanin content of black-berry genotypes ranged from a low of 1143.9 mg/kg FW for Chickasaw toa high of 2415.4 mg/kg for Apache, reflecting a 2.1-fold difference in totalanthocyanin content among genotypes. In most cultivars, cyanidin 3-glu-coside was the predominant anthocyanin (75% to 84% of total anthocya-nins). The minor anthocyanins identified included cyanidin 3-rutinoside(0.7% to 12.1%), cyanidin 3-xyloside (4.0% to 8.1%), cyanidin 3-malonyl-glucoside (1.8% to 3.1%), and cyanidin 3-dioxalyglucoside (2.7% to 8.0%).Siriwoharn et al.65 evaluated the proportions of individual anthocyaninsamong 11 blackberry cultivars and found that cyanidin 3-glucoside rangedfrom 69.8% to 93.9%, cyanidin 3-glucoside acylated with malonic acidranged from 0.15% to 3.92%, and cyanidin 3-rutinoside, cyanidin-xyloside,and cyanidin 3-dioxalylglucoside ranged from none detected to 29.9%,6.59%, and 5.91%, respectively. The primary anthocyanins in marionberrywere cyanidin 3-glucoside (57% to 73%) and cyanidin 3-rutinoside (24% to37%). The anthocyanin in Evergreen blackberries was predominantly cya-nidin 3-glucoside (70% to 85%).



Wada and Ou66 showed that anthocyanins in Evergreen blackberries andmarionberries were predominantly cyanidin 3-glucoside and cyanidin3-(6′-p-coumaryl) glucoside. For red raspberries, cyanidin 3,5-diglucosidewas the major anthocyanin. The primary anthocyanins in boysenberries werecyanidin 3-(6′-p-coumaryl) glucoside-5-glucoside and cyanidin 3-glucoside,whereas cyanidin 3-(6′-p-coumaryl) sambubioside and cyanidin 3-(6′-p-coumaryl) glucoside were the primary anthocyanin forms present in blackraspberries. Others have identified cyanidin 3-sophoroside as a major antho-cyanin in red raspberries and boysenberries, and cyanidin 3-rutinoside as amajor anthocyanin in black raspberries.74

The major anthocyanins in six black currant cultivars were delphinidin3-glucoside, delphinidin 3-rutinoside, cyanidin 3-glucoside, and cyanidin3-rutinoside. Delphinidin 3-rutinoside was the predominant anthocyanin.Ben Alder and Ben Nevis had the highest content of delphinidin 3-gluco-side and Ben Nevis had the highest content of delphinidin 3-rutinoside.Large amounts of cyanidin 3-glucoside and cyanidin 3-rutinoside werefound in Ben Alder, Ben Nevis, Ben Lomond, and Ben Tirran.75 Cyanidin3-glucoside and cyanidin 3-sambubioside were found to be the majoranthocyanins in elderberries, while cyanidin 3-glucoside and cyanidin3-rutinoside were the major anthocyanins in gooseberries. Whinham andLancashine gooseberries contained higher amounts of anthocyanins com-pared to two other cultivars.75 Chokeberries contained higher amounts ofanthocyanins than blackberries, blueberries, cranberries, currants, goose-berries, and elderberries. Cyanidin 3-galactose and cyanidin 3-arabinosidewere the two main anthocyanins found in chokeberries.60,75 The anthocy-anin in nine cultivars of sweet rowanberries (6 to 80 mg/g FW) consistedmainly of three compounds: cyanidin 3-galactoside (major), cyanidin3-glucoside, and cyanidin 3-arabinoside.70

5.2.2 Antioxidant capacity affected by varieties and genotypes

Berry fruits have received much attention since being reported to containhigh levels of oxygen radical-absorbing capacity. The high antioxidantactivities in berry fruits are largely attributed to phenolic compounds, suchas anthocyanins, and to other flavonoid compounds. The activity is gen-erally considered to be dependent on their structure and content in berries.However, synergistic interactions between phenolics and other compo-nents of berry fruits have also been observed to influence the antioxidantactivity of berry fruits. These compounds may act independently or incombination as anticancer or cardioprotective agents by a variety of mech-anisms. The antioxidant activities of phenolic compounds are mainly dueto their redox properties, which can play an important role in absorbingand neutralizing free radicals, quenching singlet and triplet oxygen, ordecomposing peroxide.18

It is well established that a strong and positive relationship exists betweentotal phenolic and anthocyanin contents and antioxidant activity.56,76–78



This suggests that breeders can select for higher phenolic content and greatercolor intensity in order to increase antioxidant capacity. Wild berries havesignificantly higher antioxidant activities than domestic berries and also ahigher phenolic content.32,76,79

5.2.2.1 FragariaDifferent strawberry cultivars vary in their antioxidant activity (ORAC)values, anthocyanin content, and total phenolic content.77 ORAC valuesfor the different strawberry cultivars ranged from 12.2 to 17.4 µmol ofTrolox equivalents (TE)/g FW. Earliglow had the highest ORAC value(17.4 µmol TE/g FW), anthocyanin content (45.3 mg/100 g FW), and totalphenolic content (152 mg/100 g FW). Meyers et al.80 measured the totalfree and bound phenolics, total flavonoids, and total anthocyanin contentof eight strawberry cultivars and found free phenolic content differed by65% between the highest (Earliglow) and the lowest (Allstar) ranked cul-tivars. The water-soluble bound and ethyl acetate soluble-bound phenoliccontents averaged 5% of the total phenolic content of the cultivars. Thetotal flavonoid content of Annapolis was twofold higher than that ofAllstar. The anthocyanin content of the highest ranked cultivar, Evange-line, was more than double that of the lowest ranked cultivar, Allstar.Earliglow (134.1 ± 3.0 µmol vitamin C/g FW) had the highest total anti-oxidant activity. The lowest total antioxidant activity occurred in Allstar,while activity in the other cultivars ranged from 59.9 µmol vitamin C/gFW for Mesabi to 36.7 µmol vitamin C/g FW for Jewel. Scalzo et al.81

evaluated six different strawberry cultivars and found the antioxidantcapacity of strawberries was strongly influenced by species and cultivar.The wild species F. vesca had the highest antioxidant activity values, whichwere 2.5-fold higher than the average of the most common cultivatedItalian strawberry varieties. Patty (16.03 µmol TE/g FW) and Sveva (14.73µmol TE/g FW) had the highest total antioxidant activity, followed byOnda (13.81 µmol TE/g FW) and Camarosa (12.52 µmol TE/g FW). Ideaand Don had the lowest total antioxidant activity values (11.90 and 10.58µmol TE/g FW, respectively).

Wang and Jiao82 showed that strawberry cultivars differed in theirscavenging capacity against different reactive oxygen species. The antiox-idant capacity value against O2

•− for strawberries ranged from 40.4 to 51.4µmol a-tocopherol/10 g FW. Earliglow inhibited 73.6% of O2

•−, which wasthe highest level among all of the strawberry cultivars. Allstar had thelowest O2

•− scavenging efficiency, with only 57.9% inhibition of O2•− produc-

tion. The antioxidant capacity values against hydrogen peroxide (H2O2) instrawberry ranged from 15.9 to 20.7 µmol ascorbate/10 g FW. Earliglowalso had the highest scavenging efficiency against H2O2 and OH•, whileAllstar had the lowest. Red Chief showed the highest antioxidant capacityvalues against 1O2 and also the highest efficiency for inhibiting 1O2, whileAllstar had the lowest.82



5.2.2.2 VacciniumBlueberries have a high antioxidant capacity compared to other fruits.76,83

Among the blueberry cultivars, antioxidant activity ranged from 8.1 to38.3 µmol TE/g FW.56 The average antioxidant activity values for rabbiteyeblueberries and southern highbush were 27.60 and 14.83 µmol TE/g FW,respectively. Prior et al.76 reported an overall range in antioxidant activityfrom 13.9 to 45.9 µmol TE/g FW in their study of northern and southernhighbush, rabbiteye, and lowbush blueberry genotypes harvested in a singleyear, with considerable overlap in antioxidant activity values among thegenotypes of different species. The Premier cultivar of rabbiteye blueberriesgave the highest antioxidant capacity value of 38.29 µmol TE/g FW. Climaxgave the lowest antioxidant capacity of 19.73 µmol TE/g FW among therabbiteye blueberries. The average content of total anthocyanins, totalpolyphenols, and total antioxidant capacity of rabbiteye blueberries werehigher than those of southern highbush.56 Kalt et al.84 found lowbush blue-berries were consistently higher in anthocyanins, total phenolics, and anti-oxidant capacity compared with highbush blueberries.

Howard et al.85 reported that ORAC values of 18 blueberry cultivarsranged from a low of 20.5 mmol TE/kg FW in Magnolia to a high of 60.3 mmolTE/kg FW in US-497, reflecting a 2.9-fold difference. Other studies reportthat ORAC values among blueberry genotypes vary 1.8-fold,86 2.5-fold,76

3.3-fold,56 4.7-fold,87 5.2-fold,78 and 6.8-fold.88 These indicate that amplegenetic variation exists for exploitation by plant breeders. Moyer et al.78

evaluated 30 genotypes of nine species of Vaccinium and found V. ashei hadthe highest antioxidant capacity, with ORAC values of 110.8 to 130.7 µmolTE/g FW and ferric-reducing antioxidant power (FRAP) values of 127.1 to157.3 µmol TE/g FW, followed by V. angustifolium, V. ovatum Pursh, and V.parvifolium Smith.

Wang and Stretch89 showed significant differences in antioxidant activity,anthocyanin, and total phenolic content among various cultivars of cranber-ries. Early Black had the highest ORAC value (14.1 µmol TE/g FW), followedby Franklin, Crowley, Wilcox, Ben Lear, Howes, Stevens, Cropper, andPilgrim. Crowley and Early Black had the highest anthocyanin content(65.6 and 63.4 mg/100 g FW, respectively). Significant differences in totalphenolic content among the cultivars were also evident. Early Black had thehighest total phenolic content (176.5 mg/100 g FW). Among the differentcranberry cultivars, Early Black stood out as having the highest antioxidantcapacity values against O2

•−, H2O2, OH•, and 1O2 and scavenging capacity toinhibit reactive oxygen species. Howes had the lowest scavenging capacityamong all of the tested cranberry cultivars for O2

•−, OH•, and 1O2. Ben Learhad the lowest inhibition of H2O2.

82

Lingonberries contain potent free radical scavenging activities for DPPH•,ROO•, OH•, and O2

•− radicals. The ORAC values of 12 cultivars of lingonberriesranged from 58.5 to 223.6 µmol TE/g FW, with the cultivar Ammerland yield-ing the highest ORAC value, total phenolic content, and total anthocyanin



content, and Sanna having the lowest.61 Deerberries not only possessed anti-oxidant activities against DPPH radicals and ABTS•+ radicals, but also had thecapacity to scavenge ROO•, O2

•−, H2O2, OH•, and 1O2. Among the genotypestested, B-76 had the highest scavenging capacity of active oxygen species. Thevalues for DPPH radicals and ABTS•+ for B-76 extracts were 4.47 mg FW and2.92 µmol Trolox/g FW, respectively. The antioxidant capacity against ROO•

was 68.5 µmol Trolox/g FW. The scavenging capacity for O2•−, H2O2, OH•, and

1O2 in B-76 fruit juice were 50.4, 2.0, 15.9, and 7.6 µmol ascorbate/g FW,respectively (Wang, S.Y., et al., unpublished data).

5.2.2.3 RubusBlackberries and raspberries are also excellent sources of natural antioxi-dants. Antioxidant activities differ among cultivars. The ORAC values forblackberries ranged from 13.7 to 28.8 µmol TE/g FW, with Hull Thornlessyielding the highest ORAC value compared to the Chester Thornless andTriple Crown cultivars.77 Hull Thornless also had the highest antioxidantcapacities against O2

•− (72.0% inhibition), H2O2 (73.9% inhibition), OH• (76.7%inhibition), and 1O2 (15.8% inhibition), while Blacksatin was consistently theleast able to cause inhibition of all these reactive oxygen species.82

Thomas et al.90 studied six cultivars of blackberries and showed LochNess had the highest and Arapaho had the lowest total antioxidant activity.Siriwoharn et al.65 evaluated 11 blackberry cultivars and found ORAC valuesranged from 37.6 to 75.5 µmol TE/g FW and FRAP values ranged from 63.5to 91.5 µmol TE/g FW. ORUS 1489-1, Marion, and Evergreen were varietiescontaining the highest FRAP values. Deighton et al.91 analyzed the antioxi-dant properties of 18 domesticated and wild Rubus species and found theantioxidant capacity ranged from 0 to 25.3 µmol TE/g FW and FRAP valuesranged from 190 to 66,000 µmol/l. Prior et al.76 reported Rubus caucasicushad the highest phenolic content and antioxidant capacity, close to thatreported for blueberries.

For raspberry, ORAC values ranged from 7.8 to 33.7 µmol TE/g FW.Jewel, a black raspberry, had the highest ORAC value and also yielded thehighest anthocyanin and total phenolic content compared to the other redraspberry cultivars.77 In raspberry, the antioxidant capacity values againstO2

•− ranged from 28.5 to 46.7 µmol α-tocopherol/10 g FW, whereas the anti-oxidant capacity values against H2O2 ranged from 12.6 to 20.8 µmol ascor-bate/10 g FW. Jewel consistently had the best scavenging capacity for thereactive oxygen species O2

•−, H2O2, OH•, and 1O2, with 66.9%, 71.5%, 77.3%,and 10.2%, respectively. Canby had the lowest ability for inhibiting freeradical activity for O2

•−, H2O2, OH•, and 1O2, with 40.8%, 43.5%, 52.4%, and7.2%, respectively.82

Wada and Ou66 evaluated five types of caneberries (Evergreen blackber-ries, marionberries, boysenberries, red raspberries, and black raspberries)and found that all had high ORAC activity ranging from 24 to 77.2 µmolTE/g FW. The ORAC values of marionberries, Evergreen blackberries (28 µmolTE/g FW), and red raspberries (24 µmol TE/g FW) were similar to those



reported by Wang and Lin.77 The ORAC values for boysenberry (42 µmolTE/g FW) was higher than those seen in either red raspberry or blackberry,but the ORAC value in the Munger black raspberry (77 µmol TE/g FW) wasmuch higher than the levels in the other caneberries. Moyer et al.78 analyzed37 Rubus species and cultivars and reported that Rubus occidentalis L. andhybrid black raspberries (Earlysweet, Jewel, and Munger) had the highestantioxidant activities, with ORAC values ranging from 100.3 to 146.0 µmolTE/g FW and FRAP values ranging from 169.1 to 205.6 µmol TE/g FW. InRubus species and Rubus hybrid blackberries, ORAC values ranged from 26.7to 78.8 µmol TE/g FW and FRAP values ranged from 43.4 to 106.1 µmol TE/g FW. In Rubus species, the ORAC values of raspberries ranged from 13.1µmol TE/g FW (R. innominatus S. Moore) to 45.2 µmol TE/g FW (R. niveusThunb.) and FRAP values ranged from 19.9 µmol TE/g FW (R. innominatusS. Moore) to 69.4 µmol TE/g FW (R. niveus Thunb.).

5.2.2.4 RibesBlack currant had more than twice the phenolics and antioxidant capacityvalues of red currant and gooseberry. In black currant, total antioxidantcapacity values ranged from 50.1 to 101.4 µmol TE/g FW, with Ben Aldercontaining the greatest amount. In gooseberry, total antioxidant capacityvalues ranged from 20.8 to 41.4 µmol TE/g FW, with Lancashine having thegreatest, while Careless had the lowest.75 Moyer et al.78 evaluated 40 Ribesgenotypes, including R. uva-crispa L. gooseberries, R. nidigrolaria Bauer jos-taberries, R. nigrum L. and hybrids, R. odoratum Wendl, and R. valdivianumPhil, and found the highest antioxidant capacity was in R. valdivianum, withan ORAC value of 115.9 µmol TE/g FW and a FRAP of 219.3 µmol TE/gFW. Meanwhile, R. uva-crispa L. had the lowest ORAC (17.0 µmol TE/g FW)and FRAP (25.2 µmol TE/g FW) values.

5.2.2.5 Aronia, Sambucus, and SorbusChokeberries (Aronia) and elderberries (Sambucus) had higher antioxidantcapacities and total phenolics than other species of berry fruits.60,75 Benvenutiet al.92 also found that black chokeberries (Aronia melanocarpa Elliott) hadhigh total polyphenols (690.2 mg/100 g FW), total anthocyanins (460.5 mg/100 g FW), and antioxidant activity compared to black currants, blackberries,red currants, and raspberries. Hukkanen et al.70 studied nine sweet rowan-berries (Sorbus aucuparia L.) (Burka, Dessertnaja, Eliit, Granatnaja, Kubovaja,Rosina, Rubinovaja, Titan, and Zholtaja) and reported that they all had highantioxidant capacities, as indicated by the FRAP and DPPH methods. FRAPvalues ranged from 61 to 105 µmol Fe2+/g FW and DPPH radical scavengingactivity ranged from 21.3 to 9.7 g berry FW/g DPPH radical with Rosinahaving the lowest and Rubinovaja having the highest antioxidant capacity.These cultivars also had the lowest and highest total phenolic contents,respectively. Chokeberries, elderberries, and sweet rowanberries wereamong the berries with the highest antioxidant capacities. There was a highcorrelation between antioxidant capacity and phenolic content.70



The variation in antioxidant capacity detected among the differentgenotypes of berry fruits highlight the existence of unexploited variabilityin cultivated and wild germplasm. On this basis, well-focused breedingprograms can create new varieties specifically selected for improved fruitquality and antioxidant potential.

5.3 Production environment and growing seasonVariations in antioxidant activity, anthocyanin, and phenolic content inberry fruits can be affected by a variety of environmental factors, includ-ing growing season, growing region, and cultivation technique. Differentgrowing regions and growing seasons have different climatic conditionsand can influence the nutritional composition and antioxidant activity ofberry fruits. Biotic and abiotic conditions can vary markedly from yearto year and location to location, affecting the content of phenolic compo-nents.94 Growing temperature and light intensity have been shown toinfluence the nutrient content of fruits. Increased light intensity resultsin higher ascorbic acid content in strawberry fruit compared to fruitproduced under lower light intensities.94 Strawberries grown under hightemperature conditions showed significantly higher flavonoids contentand antioxidant capacity. Plants grown in cool day and night tempera-tures generally had the lowest antioxidant capacity.95 The composition offlavonols in red raspberry juice was also influenced by environmentalfactors.67,69 Therefore environmental conditions (temperature, moisture,irradiation, soil fertility) have a strong influence on the phytochemicalcontent in berry fruits.

5.3.1 Growing region

Häkkinen and Törrönen36 showed the importance of growing region on theamount of p-coumaric acid in strawberry fruit. The Senga Sengana varietycontained 1.8 mg/100 g FW p-coumaric acid when grown in Finland, butonly 0.7 mg/100 g FW when grown in Poland. Differences in caffeic acidand quercetin content among blueberry cultivars grown in two differentparts of Finland were also found. The total phenolic content was higher inNorthcountry and Northblue cultivars grown in Piikkiö, in southwesternFinland (5.0 and 6.3 mg/100 g FW, respectively) compared to the samecultivars in Kuopio, in eastern Finland (4.4 and 4.7 mg/100 g FW). The wildVaccinium species collected from two different parts of Finland had markeddifferences in quercetin levels of lingonberries and cranberries than thoseobserved in cultivated blueberries.36 The effect of the cultivation site wasinvestigated in the cultivar Senga Sengana, grown both in southern Swedenand in Poland. There were differences in the fruit between the two cultivationsites in the content of ascorbic acid, chlorogenic acid, kaempferol, quercetin,and ellagic acid.96



Connor et al.97,98 found that the antioxidant content in blueberries har-vested in Minnesota, Michigan, and Oregon varied significantly across loca-tions and years. The antioxidant activities of Bluegold and Northland weresubstantially lower in Michigan than in Minnesota and Oregon. Prior et al.76

found no substantial difference in antioxidant activity in Jersey harvested atsites in Oregon, Michigan, and New Jersey in a single year, but Connoret al.97,98 showed differences between these locations and also showed variabilitybetween years. This may reflect differences in climate and cultural practicesamong locations, including differences in ultraviolet radiation, temperature,water stress, and mineral nutrient availability.

5.3.2 Growing season

Howard et al.85 compared the ORAC values for 18 blueberry genotypes intwo growing seasons and found that 7 genotypes had higher ORAC valuesin 2000, 4 had higher values in 2001, and 7 had similar values over the twogrowing seasons. The differences in ORAC values between the two growingseasons was more than 60% within some genotypes. Connor et al.97,98 alsofound that in several highbush and interspecific hybrid blueberry cultivarsgrown at three locations, the antioxidant capacity (ORAC), total phenolics,and total anthocyanins varied considerably over two growing seasons. Kaltand McDonald99 found that seasonal variations in anthocyanin contentamong lowbush blueberry cultivars over seven seasons was quite remark-able in fruit harvested from the same site. Anthocyanin content varied byup to 2.4-fold for Blomidon, 1.8-fold for Cumberland, and 2.0-fold for Fundy.Olsson et al.96 showed some variation in antioxidant activity, ascorbic acidcontent, and ellagic acid content between 1999 and 2000 within each straw-berry cultivar. The total folate content in 13 strawberry cultivars harvestedin 1999 and 2001 was higher than in those harvested in 2000.

Increased light intensity resulted in higher ascorbic acid content instrawberry fruit compared to the same varieties produced under lower lightintensity.94 Strawberries grown under high temperature conditions showedsignificantly higher flavonoids content and antioxidant capacity than thosegrown under low temperature conditions. Plants grown in cool day andnight temperatures generally had the lowest antioxidant capacity.95 Oneexplanation for this difference could be related to different flavonoid con-centrations.95 The composition of flavonols in red raspberry juice was alsoinfluenced by cultivar, processing, and environmental factors.69 These datasuggest a significant influence of climatic conditions on flavonoid contentand antioxidant activity. Therefore berry genotypes should be screened overmultiple seasons in order to determine their antioxidant capacity, anthocy-anin, and phenolic-rich germplasm for breeding.

5.3.3 Cultivation techniques

Cultural practices such as conventional or organic cultivation, the use ofcompost as a soil supplement, enhancing carbon dioxide (CO2) in the



atmosphere, or applying naturally occurring compounds can all affect thephytochemical and antioxidant capacities of berry fruits. Woese et al.100

reported that the optimal conditions for plant growth generally result in thehighest levels of antioxidants.

Asami et al.101 showed that higher levels of total phenolics were con-sistently found in organically and sustainably grown cultivations of mari-onberry and strawberry as compared to those produced by conventionalagricultural practices. However, Häkkinen and Törrönen36 found that levelsof flavonols and phenolic acid were similar in the cultivars of Polka andHoneoye cultivated both by conventional and organic techniques. In onlyone cultivar, Jonsok, did the organically cultivated berries have a 12% higherconcentration of total phenolics (61.1 mg/100 g FW) compared to thosecultivated conventionally (54.4 mg/100 g FW). This difference was due tothe higher content of ellagic acid and kaempferol in strawberries cultivatedby organic culture than in those cultivated by conventional techniques.36 Thehigh content of kaempferol could be a response to pathogenic attack inorganically grown strawberries, since kaempferol can act as an antimicrobialcompound in plants.102

Compost as a soil supplement increases organic matter in the soil,which also enhances antioxidant content in strawberries.103 The oxygenabsorbance capacity for peroxyl radical, superoxide radical, hydrogenperoxide, hydroxyl radical, and singlet oxygen in strawberries increasessignificantly with increasing compost use.103 Plants grown with compostyield fruits with high levels of phenolics, flavonol, and anthocyanin.103 Itis possible that compost causes changes in soil chemical and physicalcharacteristics, increases beneficial microorganisms, and increases nutri-ent availability and uptake, thus favoring plant and fruit growth. Straw-berry plants grown with different soil nutrients also show differences inascorbic acid content. Plants grown in low organic matter and low cationexchange capacity sandy soil amended with calcium, magnesium, andnitrogen produced more ascorbic acid than plants without supplementalfertilizer.104

Using different mulches for growing strawberries also affects straw-berry fruit quality. Different mulches probably lead to differences in can-opy temperature, soil temperature and moisture content, and the quantityand quality of light transmitted, reflected, or absorbed. In turn, thesedifferences affect plant growth, development, fruit quality, and carbohy-drate metabolism in strawberry plants. Fruit from a hill plasticulture pro-duction system has a higher flavonoid content and antioxidant capacitycompared to fruit from plants grown in a matted row system.42 In general,phenolic acid and flavonol content, as well as cyanidin- and pelargonidin-based anthocyanins and total flavonoids are greatest in the hill plasticulturesystem. Fruits from plants grown in the matted row system generally havethe lowest content of phenolic acids, flavonols, and anthocyanins. Fruitgrown under hill plasticulture conditions have the highest peroxyl radicalabsorbance capacity.42



Carbon dioxide concentrations in the atmosphere may also have an effecton antioxidant capacity. Higher carbon dioxide concentrations in the fieldresulted in an increase in anthocyanins, phenolics, and antioxidants in straw-berry fruit.105 Plants grown in carbon dioxide-enriched conditions had higherscavenging capacity for reactive oxygen species and oxygen radical absor-bance activity against ROO•, O2

•−, H2O2, OH•, and 1O2 radicals.105

Jasmonic acid (JA) and its methyl ester (methyl jasmonate, MJ) are in aclass of oxylipins derived from the lipoxygenase-dependent oxidation offatty acid. Both compounds have been found to occur naturally in a widerange of higher plants. JA/MJ play key roles in plant growth and affect awide range of physiological and biochemical processes.106 Preharvest sprayingof MJ significantly enhances anthocyanin, total phenolic, and flavonoidcontent and antioxidant capacity in raspberries.107 MJ results in the stimulationof anthocyanin biosynthesis in strawberry ripening.108

5.4 MaturityAntioxidant capacity and polyphenolic content vary considerably with dif-ferent stages of maturity. Lingonberries, blackberries, raspberries, strawber-ries, and other berry fruits usually have the highest ORAC values and totalphenolic content when at the green stage, whereas they have the lowestORAC values when at the pink stage. Following the pink stage, many phy-tonutrients are synthesized in parallel with the overall development andmaturation of fruits. Fruit harvested during the ripe stage consistently yieldhigher antioxidant values than that harvested during the pink stage. Thehigh antioxidant values at the green stage may be due to the procyanidincontent in the immature fruit and the high ORAC values during the ripestage may be because of high anthocyanins in mature fruit.61,77

Black raspberries had the highest ORAC values and total phenolics atthe green stage, but red raspberries had their highest ORAC values at theripe stage. In red raspberry, anthocyanin content steadily increased with fruitmaturity, but the total phenolic content showed a decrease from the greento the pink stage, followed by a significant increase from the pink stage tothe ripe stage.77 In strawberry, small green stage fruit had the highest ORACvalue and total phenolic content, both of which steadily decreased until the50% red stage. Beyond the 50% red stage, the ORAC value and anthocyanincontent then steadily increased with fruit maturity, but the total phenoliccontent remained at relatively low levels.77

Kosar et al.41 showed that the major compounds in strawberries wereellagic acid during the green stage, pelargonidin-3-glucoside and p-cou-maric acid during the pink stage, and pelargonidin-3-glucoside and p-cou-maric acid during the ripe stage. The content of ellagic acid decreased withmaturity. The concentration of ellagic acid in the strawberry cultivarsCamarosa, Dorit, Chandler, and Osmanli and their hybrids was found tobe between 0.45 and 2.20 mg/100 g FW in the green stage, 0.12 and 2.08mg/100 g FW in the pink stage, and 0.22 to 1.19 mg/100 g FW in ripe stage.



Green strawberry fruit pulp has been found to contain about twice as muchellagic acid as red fruit pulp.44 Williner37 reported that the ellagic acidconcentration decreased in the Camarosa (from 12.9 to 4.47 mg/100 g FW)and Chandler (from 17.8 to 4.13 mg/100 g FW) varieties during the ripeningprocess.

The highest amounts of anthocyanins were obtained from ripe strawber-ries. The content of both cyanidin-3-glucoside and pelargonidin 3-glucosideincreased significantly during ripening in all genotypes. The amount of p-cou-maric acid also significantly increased during maturation. p-Coumaric acidranged from 0.35 to 1.22 mg/100 g FW in the green stage, 0.32 to 2.90 mg/100 g FW in the pink stage, and 0.41 to 5.82 mg/100 g FW in the ripe stage.There were no differences in flavonoid content between green and ripe fruit.41

Häkkinen and Törrönen36 found no significant difference in the concentra-tion of p-hydroxybenzoic acid between different maturation stages in the SengaSengana strawberry (0.4 mg/100 g FW). Olsson et al.96 found that the contentof chlorogenic acid, p-coumaric acid, quercetin, and kaempferol increased withripening in Honeoye, whereas less difference was seen in Senga Sengana.

In blueberries, the concentration of cinnamate derivatives generallydecreases during ripening.109 However, slightly unripe lowbush blueberrieshave the same concentration of chlorogenic acid as fully ripe and overripefruit. During blueberry ripening, the anthocyanin concentration alsoincreased from 0 to about 11 mg/g DW and in highbush blueberries, theanthocyanin content was substantially higher at advanced stages of ripeningthan in berries that were less ripe.99,110 Increased maturity at harvest increasedthe ORAC value and the anthocyanin and total phenolic content. Immatureblueberries harvested at an early stage (immediately after turning blue) hadlower ORAC values and total anthocyanin content than more mature blue-berries harvested 49 days later. In ripe blueberries, both anthocyanins andtotal phenolics were strongly correlated with ORAC values.76 In cranberries,the ripe berries contained significantly more quercetin and myricetin thanmedium ripe berries.62

In lingonberries, Wang et al.61 evaluated 13 different genotypes andfound that fruit harvested during the green stage consistently yielded thehighest ORAC values and total phenolic content. The ORAC values in lin-gonberries ranged from 58.5 to 223.6 µmol TE/g FW, with Ammerlandyielding the highest ORAC value. The total phenolic content was highest atthe green and red stages of maturity. Ammerland had the greatest free radicalscavenging activities against the DPPH radical, with a median effective dose(ED50) of 5.91 mg FW, which is equivalent to 95.1% of inhibition. The DPPHradical scavenging activity is correlated to the ORAC value with R2 = 0.8009.This indicates that the antioxidant capacity of lingonberry can be measuredby both the ORAC and DPPH radical scavenging assays.

Siriwoharn et al.65 showed that total anthocyanin pigments increasedfrom 74.7 to 317 mg/100 g FW from the underripe to overripe stages forMarion blackberries and from 69.9 to 164 mg/100 g FW for Evergreen



blackberries. Total phenolics did not change markedly with the stage ofmaturity, with values only slightly decreasing from the underripe to ripestages. Antioxidant activity also increased with ripening in Rubus L.hybrids.65 Wang and Lin77 and Perkins-Veazie et al.111 observed the sametrend of an increase in total anthocyanin content from green to ripe in severalthornless blackberry cultivars. Vvedensksya and Vorsa112 found proanthocy-anidins in Stevens cranberry increased during maturation and reached 126.2mg/100 g FW at harvest. The proanthocyanidin content in Lear increasedby 31% during fruit ripening to a level of 79.9 mg/100 g FW. Flavonols andanthocyanins also increased in cranberries during fruit ripening.62,112 Bilykand Sapers62 observed a positive correlation between total anthocyanin con-tent and maturity in several thornless blackberry cultivars (79.3 to 112 mg/100 g FW; from red to black). In addition, ORAC values increased from 43.0µmol TE/g FW to 62.7 µmol TE/g FW for Marion and from 46.1 µmol TE/g FW to 64.4 µmol TE/g FW for Evergreen during ripening. Wang and Lin77

reported a reduction in total phenolic content from the green to ripe stage(295 mg/100 g FW to 226 mg/100 g FW).

Beekwilder et al.113 found that the dominant antioxidants in raspberryare anthocyanins, ellagitannins, and proanthocyanidin-like tannins. Cyani-din 3-glucoside was present in unripe and ripe fruit, while cyanidin sophoro-side, cyanidin glucosylrutinoside, and pelagonidin glucosylrutinoside werepresent only when the red color of the fruit developed. The level of tannins,both ellagitannins and proanthocyanidin-like tannins, decreased substan-tially during fruit ripening. The findings presented here suggest that thecontent of individual health-promoting compounds in raspberry can varysignificantly according to their developmental stage.

5.5 Postharvest handlingMost berry fruits reach their maximum nutrient content when fully mature.However, many of these fruits are usually harvested at a slightly immaturestage while they have a more firm texture in order to facilitate handlingand transportation and to minimize mechanical damage of the berries. Thefruit may continue to mature and increase in antioxidant and nutrient valuein storage. Different postharvest handling methods can affect phytonutri-ent levels in berry fruits. Several techniques have been shown to be effectivein maintaining postharvest quality and extend the storage life of berryfruits. These techniques include temperature management, atmospheremodification, heat treatment, irradiation, and treatment with naturallyoccurring substances such as methyl jasmonate. Usually phytonutrientlevels decline when fruits start to spoil and tissues begin to break down.Therefore any postharvest treatment that is beneficial in maintaining thequality of fresh produce can also help in maintaining antioxidant andnutritional values.



5.5.1 Storage conditions

Levels of nutrients in fruits can increase or decrease during postharveststorage depending upon the type of fruit, temperature, and storage environ-ment. Increases in anthocyanin content during storage have been reportedfor cranberries,89 lowbush blueberries,99 rabbiteye blueberries,114 highbushblueberries,86 and strawberries.115,116

In cranberries, postharvest storage temperatures between 0°C and15°C increased antioxidant capacity, anthocyanin, and total phenolic con-tent.89 Strawberries stored at 4°C showed good retention of vitamin C,117

but less chlorgenic acid and quercetin.96 Kalt et al.118 found that anthocy-anin concentration and surface color increased in strawberries duringstorage. Temperature, and to a lesser extent light, affected the rate ofstrawberry color development. At 20°C, anthocyanins accumulated muchmore rapidly than at 30°C, and there was a significant increase in thesurface color rating of white-harvest berries after storage in light.118 Gilet al.22 reported that in Selva strawberries, anthocyanin concentrationincreased 19% in whole fruit and 31% in external tissues after storage for10 days at 5°C. Strawberries and raspberries stored at temperatures greaterthan 0°C also had an increase in antioxidant capacity, anthocyanins, andtotal phenolic content, and the magnitude of the increase was related tostorage temperature.86 Ayala-Zavala et al.119 found that storage tempera-ture significantly affected the ORAC of strawberries. Chandler strawber-ries stored at 10°C or 5°C had higher antioxidant capacity, total phenolics,and anthocyanins than those stored at 0°C. In general, as storage temper-atures increased, ORAC values also increased. One explanation for thisfinding could be related to the fact that total phenolic and anthocyanincontents increase with temperature. Cordenunsi et al.120 evaluated threestrawberry cultivars (Dover, Campineiro, and Oso Grande) and found anincrease in anthocyanin during storage. The rate of anthocyanin accumu-lation increased with increasing temperature, while flavonols (quercetinand kaempferol derivatives), ellagic acid, and total phenolic contentremained almost the same at all temperatures. This result indicated thatafter harvesting there was anthocyanin biosynthesis, but no additionalflavonol synthesis.

During storage at all temperatures, there was a significant increase inthe ratio between pelargonidin and cyanidin for the three varieties of straw-berries, showing a preferential synthesis of pelargonidin over cyanidin.120

Tomas-Barberan et al.116 also found an increase in anthocyanin and ellagicacid in strawberries during air storage, whereas flavonoids and hydroxycin-namic acid derivatives remained constant.

Häkkinen et al.43,47 evaluated the effect of storage on raspberries and foundthat quercetin flavonoid content increased, while kaempferol and myricetincontent decreased during storage at –20°C. Connor et al.87 demonstrated thatchanges in antioxidant activity, anthocyanin, and total phenolic content inblueberries during cold storage were cultivar dependent. Perkins-Veazie and



Kalt121 showed that ORAC values of erect-type blackberries tended to decreasewith storage. Meanwhile, cultivar MSU-58 showed a 29% increase in antiox-idant activity after storage for 7 weeks. Antioxidant activity, total phenoliccontent, and anthocyanin content were correlated with each other in this study.Kalt et al.110 also found that ORAC values were positively correlated with totalphenolic content, but not with anthocyanin in highbush blueberry cultivars(Bergitta, Bluegold, and Nelson) during ripening and storage.

5.5.2 Controlled atmospheres

Storage of certain fruits and vegetables in an atmosphere low in oxygen andhigh in carbon dioxide may allow longer storage life.122 This storage techniqueis considered to be a supplement to refrigeration. The potential benefits fromusing controlled or modified atmosphere storage depends on the commod-ity, variety, physiological age, atmosphere composition, temperature, andduration of storage. The potential benefits from this method are retardationof senescence, suppression of biochemical and physiological changes, reduc-tion of physiological disorders in some fruits, and suppression of the growthof certain decay-causing pathogens.

Increasing carbon dioxide concentration around fruits inhibits the post-harvest increase in anthocyanin by affecting its biosynthesis, degradation,or both.22,39,115,123 Carbon dioxide-enriched atmospheres (10% to 20%) areespecially effective in retarding the decay and softening of strawberries.However, exposure to high concentrations of carbon dioxide can adverselyaffect the color change in strawberries.22 In strawberries, high carbon diox-ide storage did not affect the anthocyanin content in external tissues, butcaused a reduction in red color intensity and a decrease in the anthocyanincontent of internal fruit tissue. It is possible that high carbon dioxide causesan increase in pH, which in turn affects the stability of anthocyanins. Ascarbon dioxide levels increase, the concentration of pelargonidin glycosidesin internal tissues decrease.22 In red raspberries, ascorbic acid slightlyincreased and red pigment showed no significant changes after controlledatmosphere (10% O2 + 15% CO2 or 10% O2 + 31% CO2) storage for 7 daysat 2°C.124 Wright and Kader125 showed a controlled atmosphere (2% O2 air+ 12% CO2 or 2% O2 + 12% CO2) had no significant effect on changes intotal ascorbate content for strawberries after 7 to 8 days at 5°C. Remberget al.126 evaluated the total antioxidant capacity of Bluecrop, Hardyblue,Patriot, Putte, and Aron blueberries after 1 month of cold storage (1°C and8°C) or controlled atmosphere (10% O2 + 10% CO2) and found that the totalantioxidant capacity decreased considerably during storage in both cases.Agar et al.127 stored berry fruits in high carbon dioxide and found a decreasein vitamin C content associated with high carbon dioxide concentrations(10% to 30% CO2), particularly in strawberries. This reduction in vitaminC was moderate in black currants and blackberries and almost absent inraspberries and red currants when compared with strawberries. Ascorbicacid diminished more than dehydroascorbic acid in high carbon dioxide



atmospheres. This suggests a stimulating effect of high carbon dioxideconcentrations on the oxidation of ascorbic acid or an inhibition of mono-or dehydroascorbic acid reduction to ascorbic acid. Agar et al.127 alsoreported a decrease in ascorbic acid content in red raspberries in controlledatmosphere storage. Gunes et al.128 reported that Stevens cranberries hada higher phenolics content and total antioxidant activity than Pilgrim. Theyalso showed that for fruits stored in air, total antioxidant activity increasedby about 45%. However, this increase was not seen when the fruits werestored in 30% CO2 + 21% O2.128 The mechanism by which controlled atmo-sphere storage prevents the increase in total antioxidant activity is not clear,but controlled atmosphere conditions might affect the release of boundphytochemicals that contribute to antioxidant activity. Controlled atmo-sphere storage conditions might prevent the release of bound phenolicsand flavonoids from the cell matrix of cranberry fruits and maintain lowerantioxidant activities.

Holcroft and Kader39,115 and Holcroft et al.123 reported that the concen-trations of ellagic acid, catechin, quercetin, and kaempferol derivatives instrawberries increased during air storage, but remained constant during highcarbon dioxide storage. In Selva strawberries, Holcroft and Kader39,115 alsoreported that anthocyanin concentrations increased in both the external andinternal tissue of fruit stored in air at 5°C for 10 days, but the increase waslower in fruit stored in air enriched with 10 or 20 kPa carbon dioxide. Theactivities of phenylalanine ammonia lyase (PAL) and uridine diphosphate(UDP)-glucose:flavonoid glucosyltransferase (UFGT) decreased in bothexternal and internal tissues of strawberries stored in air + 20% kPa CO2,and the effects were more obvious in the internal tissues.

Zheng et al.129 studied the effects of superatmospheric oxygen treat-ments (40%, 60%, 80%, or 100% O2 at 5°C) on Duke highbush blueberriesand showed that antioxidant levels were markedly increased by 60% to100% oxygen treatments compared with 40% oxygen treatment or air con-trol during 35 days of storage. Elevated oxygen between 60% and 100%also promoted increases in total phenolics and total anthocyanins, espe-cially malvidin-based anthocyanins as well as the individual phenolic com-pounds. Data obtained in these studies suggest that high oxygen treatmentsmay improve the antioxidant capacity of fruits. Bangerth130 found thatlosses of ascorbic acid in red currants were reduced by storage in reducedoxygen atmospheres, but these losses were accelerated by storage in ele-vated carbon dioxide atmospheres. Stewart et al.131 also reported that softfruit stored under elevated oxygen levels exhibited good antioxidant capac-ity over the first 4 days of storage, but antioxidant capacity declined withprolonged storage, possibly due to oxygen-promoting oxidation of themain antioxidants, including anthocyanins and other phenolic compounds.This was confirmed by Pérez and Sanz132, who found that in comparisonwith fruits stored in air, strawberries held in 80% O2 + 20% CO2 hadsignificantly higher levels of total anthocyanins during the first 4 days of



storage, but significantly lower levels at the end of storage. It appears thatthe effect of high oxygen levels on total phenolics, total anthocyanins, andORAC values may vary depending on the commodity, oxygen concentra-tion, storage time, and temperature.

5.5.3 Other postharvest treatments

Prestorage heat treatments have been demonstrated to effectively maintainthe quality of fresh produce. In addition to controlling diseases and insects,adequate heat treatment can also retard senescence or degradative pro-cesses in fresh produce. Civello et al.133 evaluated the effect of heat treat-ments on Selva strawberries and found that heat treatments improvedstrawberry shelf life and delayed ripening and postharvest decay; the bestresults were obtained for fruit heated at 42°C and 48°C for 3 hours. How-ever, both treatments reduced anthocyanin accumulation and PAL activityrelative to the controls. Moreover, the anthocyanin content of fruit treatedat 48°C was significantly lower than that of fruit treated at 42°C. In contrast,Yoshikawa et al.134 treated Chandler strawberries with humid air at 43°Cand 46°C for 80 minutes and found severe damage in the fruit. Thesecontradictory results could be due to cultivar-dependent responses ofstrawberries to heat treatment.

Light has been shown to be the most important environmental factorinfluencing anthocyanin biosynthesis in plants.135 In submerged-harvestedcranberries, red light and far-red light increased the total anthocyanin levelby 41.5% and 34.7%, respectively. The level of each individual anthocyaninincreased differently under different light exposures, such as natural light,red light, and far-red light. Natural light conditions enhanced the concen-trations of cyanidin 3-galactoside, cyanidin 3-arabinoside, peonidin3-galactoside, peonidin 3-glucoside, peonidin 3-arabinoside, and cyanidin3-glucoside substantially (54% to 100%) compared to the control berries,which were kept in the dark. Red and far-red light had the most prominenteffects on cyanidin 3-glucoside and peonidin 3-arabinoside, showing a 70%to 92% increase. The biosynthesis of cyanidin 3-galactoside was leastaffected by red and far-red light, showing increases of 29% and 17%,respectively.136 These results indicate that the expression of enzymes thatcatalyze anthocyanin biosynthesis are regulated differently by environ-ments and the variation in composition of anthocyanin may be manipu-lated by different light exposure to obtain a more valuable antioxidantproduct from cranberries.135,136

Red pigmentation of berry fruits can be improved after harvesting usingartificial light irradiation. A range of wavelengths from ultraviolet B (UV-B)(280 to 320 nm) to red light (680 to 780 nm) is effective. Red light alone isonly slightly effective in stimulating anthocyanin production, UV-B has anadditional effect, and both together have a synergistic effect.137 It has beenproposed that UV irradiation induces and activates decay-resistance



mechanisms, for example, by increasing antifungal compounds in the fruitpeel. An additional positive effect of UV treatment is the enhancement ofanthocyanin levels in strawberries.138 Irradiation (2 to 3 kGy) combined withrefrigeration (6°C) storage has been shown to extend the shelf life of straw-berries.139 During storage, ascorbic acid significantly increased while dehy-droascorbic acid decreased in irradiated strawberries.139 Pan et al.140 showedthat ultraviolet C (UV-C) (4.1 kJ/m2) and heat treatment (45°C), either sep-arately or combined, reduced anthocyanins and phenolics in Seascape straw-berries compared to controls. UV-C (9.2 kJ/m2) and heat treatments (45°C)retained fruit quality and antioxidant activity better than in control fruit ofboysenberries.141

Ozone (O3) is an unstable compound that produces hydroxyl radicalsand other free radical species. Ozone has been used in different applicationsin the food industry and has been recommended as a generally recognizedas safe (GRAS) disinfectant or sanitizer for foods in the United States.142

Perez et al.143 reported that an atmosphere containing ozone (0.35 ppm) wasineffective in preventing fungal decay in Camarosa strawberries after 4 daysat 20°C. At the end of cold storage, the vitamin C content of ozone-treatedstrawberries was three times that of control fruits. A significantly loweranthocyanin content was seen in ozonated strawberries (639.08 ± 11.01 nmol/g FW) compared to untreated fruit (811.34 ± 6.81 nmol/g FW) after 3 daysat 2°C. When strawberries were stored at 20°C, a slight increase in anthocy-anin accumulation was detected in both treated and untreated fruits. Nosignificant differences were found after 4 days at 20°C.143 Blackberries storedmore than 12 days at 2°C in a 0.3 ppm ozone atmosphere showed a sharpdecrease in anthocyanin levels.144

Methyl jasmonate (MJ), a naturally occurring compound, was found tomaintain higher levels of oxygen radical absorbance capacity in blueberries,especially during the later part of storage.145 The high antioxidant activitieswere associated with better overall quality of MJ-treated raspberries, whichincluded high levels of sugars and organic acids, and a low incidence ofdecay.146 Ayala-Zavala et al.147 found that Allstar strawberry fruit treated withMJ in conjunction with ethanol showed higher antioxidant capacity, totalphenolics, and anthocyanins than those treated with ethanol alone or con-trols (untreated) during the postharvest period. Strawberry (Everest) fruittreated with 1-methylcyclopropene inhibited PAL activity and slowedincreases in anthocyanin and phenolic content.148 Özgen et al.149 found lyso-phosphatidylethanolamine accelerates color development and promoteslonger shelf life in cranberries. Chanjirakul et al. (unpublished data) studiedthe effects of various natural volatiles such as MJ, allyl isothiocyanate (AITC),essential oil of Melaleuca alternifoli (tea tree oil [TTO]), and ethanol (EtOH)on antioxidant capacities and antioxidant enzymes in berry fruits and foundthat strawberries and blackberries treated with MJ had the highest antioxi-dant capacity expressed as ORAC values after 7 days of storage. Moreover,MJ treatment enhanced the antioxidant capacity in strawberries and black-berries as measured by radical DPPH• and ABTS•+ scavenging activity in



both 7 and 14 days after storage. The ED50 of free radical DPPH• scavengingcapacity in strawberries ranged from 31.79 to 36.94 mg after 7 days of storageand 32.57 to 42.72 mg after 14 days of storage, but only 4.29 to 6.65 mg and5.10 to 7.73 mg in blackberries after 7 and 14 days of storage, respectively.MJ-treated fruits showed the highest percent inhibition for DPPH radicalsamong all of the treatments in both strawberries and blackberries. MJ treat-ment also increased scavenging capacities against ROO•, O2

•−, H2O2, OH•,and 1O2 in strawberries and blackberries, except for O2

•− scavenging capacityin blackberries stored for 14 days. Treatment with TTO or EtOH enhancedmost of these free radical scavenging capacities, except for H2O2 in straw-berries and O2

•− and 1O2 in blackberries. It is possible that the elevatedcapacity in scavenging various free radicals by these natural volatile com-pounds increased the resistance of tissues to decay.

In raspberries, treatment with MJ enhanced the activity of several anti-oxidants and antioxidant enzymes. Although AITC treatment promoted O2

•−

scavenging capacity in blackberries after 14 days of storage, it had little effecton the scavenging capacities of other radicals or antioxidant enzyme activ-ities. These results indicate that MJ may increase the resistance of tissues todecay by enhancing their antioxidant system and their free radical scaveng-ing ability, while AITC may retard decay directly through its antimicrobialproperties. Therefore it is possible to enhance antioxidant systems, reducedecay, and extend the storage life of berry fruits by treatment with naturalvolatiles (Chanjirakul et al., unpublished data).

5.5 ConclusionRemarkable variations in antioxidant content have been shown for differentcultivars, growing seasons, growing conditions, ripening stages, and condi-tions of storage. It thus seems possible to select cultivars for certain antiox-idants or groups of antioxidants. There are variations in antioxidant contentbetween growing seasons and locations, probably due to different environ-mental conditions. Technologies are needed to retard the softening processso that fruits can be harvested and marketed at a more mature stage, whenmore of the phytonutrient compounds have been biosynthesized. At thesame time, better postharvest techniques must be developed to reduce thedegradation of nutritive factors during transport and storage. Research isalso needed to develop processing techniques to reduce the degradation ofnutritive factors such as flavonoids, carotenoids, vitamins, and bioactivepeptides. The effects of preharvest conditions, maturity, and postharvesthandling on the content of phenolic compounds, anthocyanins, and antiox-idant capacity in berry fruits are summarized in Table 5.1. Recent advancesin structural and functional genomics, as well as technical advances in plantbreeding, bioengineering, and biotechnology, make it possible to createdesigner foods for the consumer. Berry fruits rich in antioxidants are helpfulin improving human health.



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Chapter 5: Antioxidant capacity and phenolic content of berry fruits 177L

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115. Holcroft, D.M. and Kader, A.A., Carbon dioxide-induced changes in colorand anthocyanin synthesis of stored strawberry fruit, HortScience, 24, 1244,1999.

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117. Hägg, M., Häkkinen, U., Mokkila, M., Randell, K., and Ahvenainen, R., Post-harvest quality of strawberries, in Agri-Food Quality II. Quality Management ofFruit and Vegetables, Hägg, M., Ahvenainen, R., Evers, R., and Tiikkkala, K.,Eds., Royal Society of Chemistry, Cambridge, U.K., 1999.

118. Kalt, W., Prange, R.K., and Lidster, P.D., Postharvest color development ofstrawberries: influence of maturity, temperature and light, Can. J. Plant Sci.,73, 541, 1993.

119. Ayala-Zavala, J.F., Wang, S.Y., Wang, C.Y., Gonzalez-Aguilar, G., and Montoya,L.C., Effect of storage temperatures on antioxidant capacity and aromacompounds in strawberry fruit, Food Sci. Technol., 37, 687, 2004

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122. Calderon, M. and Barkai-Golan, R., Food Preservation by Modified Atmospheres,CRC Press, Boca Raton, FL, 1990.



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124. Haffner, K., Rosenfeld, H.J., Skrede, G., and Laixin, W., Quality of red rasp-berry Rubus idaeus L. cultivars after storage in controlled and normal atmo-spheres, Postharvest Biol. Technol., 24, 279, 2002.

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128. Gunes, G., Liu, R.H., and Watkins, C.B., Controlled-atmosphere effects onpostharvest quality and antioxidant activity of cranberry fruits, J. Agric. FoodChem., 50, 5932, 2002.

129. Zheng, Y., Wang, C.Y., Wang, S.Y., and Zheng, W., Effect of high-oxygenatmospheres on blueberry phenolics, anthocyanins, and antioxidant capacity,J. Agric. Food Chem., 51, 7132, 2003.

130. Bangerth, F., The effect of different partial pressures of CO2, C2H4, and O2 inthe storage atmosphere on the ascorbic acid content of fruits and vegetables,Qual. Plant., 27, 125, 1977.

131. Stewart, D., Oparka, J., Johnstone, C., Iannetta, P.P.M., and Davies, H.V., Effectof modified packaging (MAP) on soft fruit quality, in Annual Report of theScottish Crop Research Institute for 1999, Scottish Crop Research Institute,Dundee, Scotland, 1999, p. 119.

132. Pérez, A.G. and Sanz, C., Effect of high-oxygen and high-carbon-dioxideatmospheres on strawberry flavor and other quality traits, J. Agric. Food Chem.,49, 2370, 2001.

133. Civello, P.M., Martínez, G.A., Chaves, A.R., and Añón, M.C., Heat treatmentsdelay ripening and postharvest decay of strawberry fruit, J. Agric. Food Chem.,45, 4589, 1997.

134. Yoshikawa, F.T., Mitchell, F.G., and Mayer, G., Moist heat treatments of straw-berries are studied, Calif. Agric., 46(2), 26, 1992.

135. Grisebach, H., Biosynthesis of anthocyanins, in Anthocyanins as Food Colors,Markakis, P., Ed., Academic Press, New York, 1982, p. 67.

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137. Arakawa, O., Hori, Y., and Ogata, R., Relative effectiveness and interactionof ultraviolet-B, red and blue light in anthocyanin synthesis of apple fruit,Physiol. Plant., 64, 323, 1985.

138. Baka, M., Mercier, J., Corcuff, F., Castaigne, F., and Arul, J., Photochemicaltreatment to improve storability of fresh strawberries, J. Food Sci., 64, 1068,1999.

139. Graham, W.D. and Stevenson, M.H., Effect of irradiation on vitamin C contentof strawberries and potatoes in combination with storage and with furthercooking in potatoes, J. Sci. Food Agric., 75, 371, 1997.



140. Pan, J., Vicente, A.R., Martinez, G.A., Chaves, A.R., and Civello, P.M., Com-bined use of UV-C irradiation and heat treatment to improve postharvest lifeof strawberry fruit, J. Sci. Food Agr. 84, 1831, 2004.

141. Vicente, A.R., Repice, B., Martinez, G.A., Chaves, A.R., Civello, P.M., andSozzi, G.O., Maintenance of fresh boysenberry fruit quality with UV-C lightand heat treatments combined with low storage temperature, J. Hort. Sci.Biotechnol., 79, 246, 2004.

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144. Barth, M.M., Zhou, M., Mercier, C., and Payne, J., Ozone storage effects onanthocyanin content and fungal growth in blackberries, J. Food Sci., 60, 1286,1995.

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148. Jiang, Y., Joyce, D.C., and Terry, L.A., 1-Methylcyclopropene treatment affectsstrawberry fruit decay, Postharvest Biol. Technol., 23, 227, 2001.

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187

chapter 6

The potential health benefits of phytochemicals in berries for protecting against cancer and coronary heart disease

Rui Hai Liu

Contents

6.1 Introduction ................................................................................................1876.2 Health benefits of phytochemicals..........................................................189

6.2.1 Role of phytochemicals in the prevention of cancer...............1906.2.2 Role of phytochemicals in the prevention of CVD .................192

6.3 Additive and synergistic effects of phytochemicals in whole foods............................................................................................195

6.4 Bioavailability and metabolism of phytochemicals .............................1966.5 Conclusion...................................................................................................199References.............................................................................................................199

6.1 Introduction

Cardiovascular disease (CVD) and cancer are ranked as the top twoleading causes of death in the United States and in most industrializedcountries. The causes of both diseases have been linked to diet andlifestyle choices. Epidemiological studies have consistently shown that ahigh dietary intake of fruits and vegetables is strongly associated withreduced risk of developing such chronic diseases.

1–4

It is estimated thatone-third of all cancer deaths in the United States could be preventedthrough appropriate dietary modification.

2,5,6

In addition, several dietary

5802_C006.fm Page 187 Wednesday, March 21, 2007 11:00 AM


patterns have been found to have significant health benefits. The Medi-terranean diet has been linked with a reduction in CVD. The character-istics of the Mediterranean diet are high monounsaturated fat, mainlyfrom olive oil; high consumption of fruits, vegetables, and grains; mod-erate consumption of alcohol; and low consumption of red meat. Anotherpattern that has been associated with health benefits is the “prudentpattern.”

7

The prudent pattern consists of higher intakes of fruits, vege-tables, legumes, whole grains, and fish. This is in contrast to the “Westernpattern” which consists of red meat, processed meats, refined grains,desserts, and high fat dairy products. People following the prudent pat-tern had a decreased risk of CVD.

7

The evidence suggests that a changein dietary behavior, such as increasing one’s consumption of fruits and vege-tables, and related lifestyle changes is a practical strategy for significantlyreducing the incidence of CVD and cancer.

8

Plant-based foods, such as fruits and vegetables, which contain signifi-cant amounts of bioactive phytochemicals (Figure 6.1) and have potent anti-oxidant activity (Figure 6.2), may provide desirable health benefits beyondbasic nutrition to reduce the risk of chronic diseases.

8

The beneficial effectsassociated with plant-based food consumption are due in part to the exist-ence of phytochemicals.

Figure 6.1

Total phenolic content of common fruits and vegetables (adapted fromSun et al.

14

and Chu et al.

15

).

Total phenolics(mg gallic acid eq/100 g sample)

0 100 200 300 400 500 600

CucumberCeleryLettucePotato

CabbageCarrot

Red PepperOnion

SpinachBroccoli

GrapefruitPear

OrangeLemonPeachBanana

PineappleStrawberryRed grape

AppleCranberry

FreeBound


Chapter 6: The potential health benefits of phytochemicals 189

6.2 Health benefits of phytochemicals

The “phyto” of the word phytochemicals is derived from the Greek word

phyto

, which means plant. Therefore phytochemicals are plant chemicals.Phytochemicals are defined as bioactive nonnutrient plant compounds infruits, vegetables, grains, and other plant-based foods that have been linkedto reductions in the risk of major chronic diseases. Although thousands ofindividual phytochemicals have been identified in fruits, vegetables, andgrains, a large percentage of phytochemicals still remain unknown and needto be identified before we can fully understand the health benefits of phy-tochemicals in whole foods.

8

Convincing evidence suggests that the benefitsof phytochemicals in fruits, vegetables, and whole grains may be evengreater than is currently understood because the oxidative stress induced byfree radicals is involved in the etiology of a wide range of chronic diseases.

9

Because phytochemicals differ widely in composition and ratio in fruits andvegetables (Figure 6.1), and often have complimentary mechanisms to oneanother, it is suggested that people consume a wide variety of theseplant-based foods.

Cells in the human body are constantly exposed to a variety of oxidizingagents. These agents may be present in air, food, and water, or they may beproduced by metabolic activities within cells, some of which are necessary

Figure 6.2

Total antioxidant activity of common fruits and vegetables (adapted fromSun et al.

14

and Chu et al.

15

).

Total antioxidant activity(µµmol vitamin C eq/g sample)

0 20 40 60 80 100 120 140 160 180 200

CucumberLettucePotatoCeleryOnion

CabbageSpinachCarrotBroccoli

Red PepperPineappleGrapefruitOrangeBananaPear

LemonPeach

StrawberryRed grape

AppleCranberry



for life. The key factor is to maintain a balance between oxidants and anti-oxidants to sustain optimal physiological conditions. Overproduction of oxi-dants can cause an imbalance, leading to oxidative stress, especially inchronic bacterial, viral, and parasitic infections.

10

Oxidative stress can causeoxidative damage to large biomolecules such as lipids, proteins, and DNA,resulting in an increased risk for chronic diseases such as cancer and CVD.

9–11

To prevent or slow down the oxidative stress induced by free radicals,sufficient amounts of antioxidants need to be consumed. Fruits, vegetables,and grains contain a wide variety of antioxidant compounds (phytochemi-cals), such as phenolics and carotenoids, that may help protect cellular sys-tems from oxidative damage and also lower the risk of chronic diseases.

12–16

Among the 11 common fruits consumed in the United States, cranberry hasthe highest total phenolic content, followed by apple, red grape, strawberry,pineapple, banana, peach, lemon, orange, pear, and grapefruit

14

(Figure 6.1).Among the 10 common vegetables consumed in the United States, broccolihas the highest total phenolic content, followed by spinach, yellow onion,red pepper, carrot, cabbage, potato, lettuce, celery, and cucumber

15

(Figure 6.1).

6.2.1 Role of phytochemicals in the prevention of cancer

Strong epidemiological evidence suggests that regular consumption of fruitsand vegetables can reduce an individual’s cancer risk.

3,4

Block et al.

4

reviewedapproximately 200 epidemiological studies that examined the relationshipbetween the intake of fruits and vegetables and cancer of the lung, colon,breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary.In 128 of 156 dietary studies, the consumption of fruits and vegetables wasfound to have a significant protective effect. The risk of cancer was two–foldhigher in persons with a low intake of fruits and vegetables than in thosewith a high intake. Significant protection was found in 24 of 25 studies forlung cancer. Fruits were significantly protective in cancer of the esophagus,oral cavity, and larynx. Fruit and vegetable intake was protective for cancerof the pancreas and stomach in 26 of 30 studies and for colorectal and bladdercancer in 23 of 38 studies. A prospective study involving 9959 men andwomen in Finland showed an inverse association between the intake offlavonoids and the incidence of cancer at all sites combined.

17

After a 24-yearfollow-up, the risk of lung cancer was reduced by 50% in the highest quartileof flavonol intake. Consumption of quercetin from onions and apples wasfound to be inversely associated with lung cancer risk.

18

The effect of onionswas particularly strong against squamous cell carcinoma. Boyle et al.

19

showed that increased plasma levels of quercetin after a meal of onions wasaccompanied by increased resistance to strand breakage by lymphocyteDNA and decreased levels of some oxidative metabolites in the urine.

Consumption of fruits in Italy was found to have a profound protectiveeffect against cancers of the upper respiratory and digestive tracts.

20

In thesame study, the relative risks of cancers of the oral cavity, pharynx, esoph-agus, and larynx were observed to be 0.4 to 0.5, which correlated with higher



fruit consumption and was found to reduce the relative risk even more incancers of the gallbladder, pancreas, prostate, and urinary tract. In a largecase-control study in San Francisco, vegetable consumption was inverselyrelated to the risk of developing pancreatic cancer.

21

It was found that thosepersons with an intake of more than five servings of vegetables per day hada 50% reduction in risk of developing the disease compared to those in thelowest consumption quantile.

21

Carcinogenesis is a multistep process, and oxidative damage is linkedto the formation of tumors through several mechanisms.

10,11

Oxidative stressinduced by free radicals causes DNA damage, which, when left unrepaired,can lead to base mutation, single- and double-strand breaks, DNA cross-link-ing, and chromosomal breakage and rearrangement.

11

This potentially can-cer-inducing oxidative damage might be prevented or limited by dietaryantioxidants found in fruits and vegetables.

Proliferation of normal healthy cells is tightly regulated by a myriad ofcell cycle proteins. These proteins work together in complex pathways toensure that the cell divides only when necessary and without error. Cellsmay respond to external mitogens, growth factors, or oxidative stressthrough the mitogen-activated protein (MAP) kinase signaling pathways.

22

Oxidative stress on the cell membrane can stimulate signaling pathways thatwill protect the cell, such as the stress-activated protein kinase/c-JunNH

2

-terminal kinase (SAPK/JNK) and p38 kinase pathways.

23

For example,oxidative stress activates apoptosis-stimulating kinase 1 (ASK1), which inturn activates the SAPK/JNK kinases MKK4 and MKK7.

24

These kinasesphosphorylate and activate JNK, which translocates into the nucleus whereit can activate other regulatory proteins such as p53 and the transcriptionfactor Elk-1. In the case of the stress response, p53 will respond by eitherarresting the cell cycle or inducing apoptosis.

25

In order to induce a G1-phasecell cycle arrest, p53 stimulates expression of the cyclin-dependent kinaseinhibitor (CKI) p21, whose role is to inhibit the cyclin D1/Cdk4 complex.

Cells under oxidative stress are susceptible to DNA damage, which maylead to mutations that alter expression or activity of key regulatory proteins.

25

Such mutations can result in deregulation of the cell cycle and subsequentuncontrolled cell proliferation, known as cancer. These cells are then unableto properly respond to further oxidative stress and are highly susceptible toadditional DNA damage. This cycle contributes to the increasing geneticinstability characteristic of tumor cells.

25

Phytochemicals appear to reverse the effects of such mutations by haltingthe uncontrolled proliferation of cancer cells in vitro through induction ofcell cycle arrest or apoptosis. For example, the flavonol quercetin has beenshown to cause a G2/M arrest and induce apoptosis in a dose-dependentmanner in PC-3 androgen-independent human prostate cancer cells.

26

Thecells were treated with 25 to 100 µM quercetin for 24 to 72 hours and themedian effective concentration (EC

50

) for growth inhibition was determinedto be 50 µM at 24 hours. Flow cytometric analysis revealed that quercetintreatment induced a G2/M accumulation. The effects of quercetin on the



relevant cell cycle proteins were then analyzed. The CKI p21 was dramati-cally induced despite the absence of p53 (PC-3 cells contain a mutation inthe p53 gene that renders it inactive). The quercetin was found to down-regulate expression of Cdc2/Cdk1, which accounted for the increase in hypo-phosphorylated Rb while the amount of total Rb protein remained constant.Cyclin B1 was down-regulated while cyclin A was unaffected. Quercetin haseffectively induced G1/S cell cycle arrest in other cell models such as colonand gastric cancers and leukemia, but it has caused G2/M arrest in others,including breast and laryngeal cancers and nononcogenic fibroblasts.

27

Recently we showed that cranberry phytochemical extracts significantlyinhibited human breast cancer MCF-7 cell proliferation.

28

Apoptotic induc-tion in MCF-7 cells was observed in a dose-dependent manner after exposureto cranberry phytochemical extracts for 4 hours. Cranberry phytochemicalextracts at a dose of 50 mg/ml resulted in a 25% higher ratio of apoptoticcells to total cells as compared to the control groups (

p

< .05). Cranberryphytochemical extracts at doses of 10 to 50 mg/ml significantly arrestedMCF-7 cells at the G0/G1 phase (

p

< .05). A constant increasing pattern ofthe G1/S index was observed in the cranberry extract treatment group, whilethe G1:S ratio of the control group decreased concomitantly between the 10-and 24-hour treatments. After 24 hours exposure to cranberry extracts, theG1/S index of MCF-7 cells was approximately six times greater than that ofthe control group (

p

<

0.05). These results suggest that cranberry phytochem-ical extracts possess the ability to suppress the proliferation of human breastcancer MCF-7 cells, and this suppression is at least partly attributed to boththe initiation of apoptosis and the G1 phase arrest.

28

Dietary phytochemicals can act to prevent cancer or interfere with itsprogression at virtually every stage of cancer development. Studies to datehave demonstrated that phytochemicals in common fruits and vegetablescan have complementary and overlapping mechanisms of action (Table 6.1),including antioxidant activity and scavenging free radicals; regulation ofgene expression in cell proliferation, cell differentiation, oncogenes, andtumor suppressor genes; induction of cell cycle arrest and apoptosis; mod-ulation of enzyme activities in detoxification, oxidation, and reduction; stim-ulation of the immune system; regulation of hormone-dependent carcino-genesis; and antibacterial and antiviral effects.

14,15,26–30

6.2.2 Role of phytochemicals in the prevention of CVD

Dietary flavonoid intake was significantly inversely associated with mortal-ity from coronary heart disease.

31

Intake of apples and onions, both high inquercetin, was inversely correlated with total and coronary mortality.

32

In arecent Japanese study, the total intake of flavonoids (quercetin, myricetin,kaempferol, luteolin, and ficetin) was inversely correlated with the plasmatotal cholesterol and low-density lipoprotein (LDL) cholesterol concentra-tions.

33

As a single phytochemical, quercetin intake was inversely related tototal cholesterol and LDL plasma levels. Joshipura et al.

34

reported that total



fruit intake and total vegetable intake were both individually associated withdecreased risk for coronary heart disease. The inverse associations betweentotal consumption of fruits and vegetables and coronary heart disease wereobserved at intakes of more than four servings per day. Subjects in theWomen’s Health Study had a relative risk of 0.68 for CVD when comparingthe highest versus the lowest quintiles of fruit and vegetable intake, and therelative risk for myocardial infarction was only 0.47. It was estimated thatthere was a 20% to 30% reduction in risk of CVD associated with high fruitand vegetable intake.

35

Most recently, in a study involving subjects fromthe National Health and Nutrition Examination Survey EpidemiologicFollow-up Study, there was a 27% lower CVD mortality with consumptionof fruits and vegetables at least three times per day compared to one timeper day. Fruit and vegetable intake was inversely associated with the inci-dence of stroke, stroke mortality, ischemic heart disease mortality, CVDmortality, and all-cause mortality.

36

Several mechanisms for the prevention of atherosclerosis by dietary anti-oxidants in fruits and vegetables have been proposed (Table 6.2). In the LDL

Table 6.1

Proposed Mechanisms by Which Dietary Phytochemicals May Prevent

Cancer

Antioxidant activityScavenge free radicals and reduce oxidative stress

Inhibition of cell proliferationInduction of cell differentiationInhibition of oncogene expressionInduction of tumor suppression gene expressionInduction of cell cycle arrestInduction of apoptosisInhibition of signal transduction pathwaysEnzyme induction and enhancing detoxificationPhase II enzymeGlutathione peroxidase (GPX)CatalaseSuperoxide dismutase (SOD)

Enzyme inhibitionPhase I enzyme (block activation of carcinogens)Cyclooxygenase-2 (COX-2)Inducible nitric oxide synthase (iNOS)Xanthine oxide

Enhancement of immune functions and surveillanceAntiangiogenesisInhibition of cell adhesion and invasionInhibition of nitrosation and nitrationPrevention of DNA bindingRegulation of steroid hormone metabolismRegulation of estrogen metabolismAntibacterial and antiviral effects



oxidation hypothesis (Figure 6.3), oxidized LDL cholesterol has been sug-gested as the atherogenic factor that contributes to CVD.

37,38

When circulatingLDLs are present at high levels, they infiltrate the artery wall and increaseintimal LDL, which can then be oxidized by free radicals. This oxidized LDLin the intima is more atherogenic than native LDL and serves as a chemotactic

Table 6.2

Proposed Mechanisms of Action by Which Dietary Antioxidants May

Prevent CVD

Antioxidant activityScavenge free radicals and reduce oxidative stressPrevent LDL oxidation

Induction of expression of hepatic LDL receptorsRegulation of sterol regulatory element binding proteins (SREBPs)Modulation of cholesterol synthesisRegulation of lipid profilesInhibition of cholesterol absorptionRegulation of prostanoid synthesis (PGE

2

)Reduction of platelet aggregationRegulation of nitric oxide (NO•) productionLowering C-reactive protein (CRP)Regulation of blood pressure

Figure 6.3

Proposed mechanism of LDL oxidation in fatty streak formation andatherosclerotic disease.



factor in the recruitment of circulating monocytes and macrophages. OxidizedLDL is typically taken up by macrophage scavenger receptors, thus inducingthe formation of

inflammatory cytokines and promoting cell proliferation,cholesterol ester accumulation, and foam cell formation (Figure 6.3).Gruel-like lipid-laden foam cell accumulation in the blood vessel, formingfatty streaks, causes further endothelial injury and leads to atheroscleroticdisease. Since oxidized LDL plays a key role in the initiation and progressionof atherosclerosis, giving dietary supplements of antioxidants capable of pre-venting LDL oxidation has been an important therapeutic approach. Dietaryantioxidants that are incorporated into LDL are themselves oxidized whenthe LDL is exposed to pro-oxidative conditions; this occurs before any exten-sive oxidation of sterol or polyunsaturated fatty acids can occur.

39

Thereforedietary antioxidants might retard the progression of atherosclerotic lesions.Cranberry extracts were found to have potent antioxidant capacity, prevent-ing in vitro LDL oxidation, with increasing delay and suppression of LDLoxidation in a dose-dependent manner.

40

The antioxidant activity of 100 g ofcranberries against LDL oxidation was equivalent to 1000 mg vitamin C or3700 mg vitamin E. In addition, phytochemicals have been shown to haveroles in the reduction of platelet aggregation, modulation of cholesterol syn-thesis and absorption, and reduction of blood pressure. It has also beenreported that cranberry phytochemical extracts significantly induced expres-sion of hepatic LDL receptors and increased intracellular uptake of cholesterolin HepG2 cells in vitro in a dose-dependent manner.

40

This suggests thatcranberry phytochemicals could enhance clearance of excessive plasma cho-lesterol in circulation through the liver.

C-reactive protein, a marker of systemic inflammation, has been reportedto be a stronger predictor of CVD than is LDL cholesterol,

41,42

suggesting thatinflammation is a critical factor in CVD. C-reactive protein is an acute phasereactant secreted by the liver in response to inflammatory cytokines.

42

Inflam-mation not only promotes initiation and progression of atherosclerosis, butalso causes acute thrombotic complications of atherosclerosis.

43

Fruit and veg-etable intake was associated with lower plasma C-reactive protein concentra-tions,

44

suggesting dietary phytochemicals can lower C-reactive protein. There-fore, the anti-inflammatory activity of phytochemicals may play an importantrole in the prevention of CVD. Dietary antioxidants also have complementaryand overlapping mechanisms of action in the prevention of CVD (Table 6.2).

6.3 Additive and synergistic effects of phytochemicals in whole foods

Phytochemical extracts from fruits and vegetables have been shown to havepotent antioxidant activity (Figure 6.2), and the combination of phytochem-icals from fruits and vegetables is proposed to be responsible for the potentantioxidant and anticancer activities of these foods.

14,15,45

The total antioxi-dant activity of phytochemicals in 1 g of apples with peel is equivalent to83.3 µmol vitamin C equivalents; to put it another way, the antioxidant value



of 100 g of apples is equivalent to 1500 mg of vitamin C.

45

This is far greaterthan the total antioxidant activity of 0.057 mg of vitamin C (the amount ofvitamin C in 1 g of apples with peel) or 0.32 µmol vitamin C equivalents. Inother words, vitamin C in apples contributes less than 0.4% of its totalantioxidant activity. Thus most of the antioxidant activity comes from otherphytochemicals, not vitamin C. The natural combination of phytochemicalsin fruits, vegetables, and whole grains is responsible for their potent antiox-idant activity. Apple extracts also contain bioactive compounds that inhibittumor cell growth in vitro. Phytochemicals in apples with peel (50 mg/mlon a wet basis) inhibit colon cancer cell proliferation by 43%. However, thiswas reduced to 29% when apple without peel was tested.

45

Recently wereported that whole-apple extracts prevented mammary cancer in a ratmodel in a dose-dependent manner.

46

At the doses comparable to humanconsumption of one, three, and six apples per day, the tumor incidences werereduced by 17%, 39% (

p

< .02), and 44% (

p

< .01), respectively, and thecumulative tumor numbers were reduced by 25%, 25%, and 61% (

p

< .01),respectively, after 24 weeks.

46

This study demonstrated that whole-appleextracts effectively inhibited mammary cancer growth in the rat model, thusconsumption of apples may be an effective strategy for cancer protection.

Different species and varieties of fruits, vegetables, and grains havedifferent phytochemical profiles.

14–16,45–49

Therefore consumers should obtaintheir phytochemicals from a wide variety of fruits, vegetables, and wholegrains for optimal health benefits. Health benefits from the consumption offruits and vegetables extend beyond lowering the risk of developing cancersand CVD: benefits also include preventive effects for other chronic diseasessuch as cataracts, age-related macular degeneration, central neurodegener-ative diseases, and diabetes.

50

The additive and synergistic effects of phytochemicals in fruits andvegetables have been proposed to be responsible for their potent antioxidantand anticancer activities.

45,50

The benefits of a diet rich in fruits and vegetablesare attributed to the complex mixture of phytochemicals present in theseand other

whole foods.

14,15,46,50

This partially explains why no single antiox-idant can replace the combination of natural phytochemicals in fruits andvegetables in achieving the observed health benefits. Thousands of phy-tochemicals are present in whole foods. These compounds differ in molecularsize, polarity, and solubility, which may affect the bioavailability and distri-bution of each phytochemical in different macromolecules, subcellularorganelles, cells, organs, and tissues. This balanced natural combination ofphytochemicals present in fruits and vegetables simply cannot be mimickedby pills or tablets.

6.4 Bioavailability and metabolism of phytochemicals

Bioavailability and metabolism are two important questions that need to beaddressed in studying the biological effects of phytochemicals in foods. Theform of antioxidants found in foods is not necessarily the same as the form



found in the blood or the targeted tissues after digestion, absorption, distri-bution, and metabolism. In order to study the mechanisms of action ofantioxidants in the prevention of chronic disease, two important questionsto be asked are: Are these phytochemicals bioavailable? Are these originalantioxidants or their metabolites the bioactive compounds? It is crucial tounderstand the bioavailability and metabolism of these compounds to gainknowledge of what compounds and how much of these compounds actuallyreach target tissues. In some cases, the original phytochemicals may beexcreted or metabolized, never actually reaching target tissue, and the activecompounds may not be the original antioxidant compounds found in foods.To date, many studies have not addressed the bioavailability and metabolismof phytochemicals from whole foods.

Examining the bioavailability of compounds from food sources can bechallenging because there are many factors that can influence bioavailability.Foods contain a wide variety of phytochemicals, and interactions with otherchemicals in the food may affect bioavailability. Phytochemicals may beconjugated with different sugar molecules (glucosides, xylosides, rhamno-sides, galactosides) and proteins or bound to other cell structures, such asfibers, which may affect the bioavailability of those compounds. Other fac-tors, such as digestion, food processing, storage, and stage of harvest, mayalso affect phytochemical bioavailability. Although much progress has beenmade in understanding the bioavailability and further metabolism of purecompounds, more work is needed to further comprehend the bioavailabilityof phytochemicals from complex food sources.

Dupont et al.

51

reported the bioavailability of phenolic compounds fromapple cider in humans. No quercetin was found in the volunteers’ plasmaafter drinking 1.1 L of apple cider. Instead, low levels of 3-methyl quer-cetin and 4-methyl quercetin were observed within 60 minutes followingconsumption of the cider. Caffeic acid was rapidly absorbed, but within90 minutes the caffeic acid in the plasma was undetectable. Catechin, epi-catechin, and phlorizin were not seen in the plasma. Hippuric acid andphloretin were both increased in the subjects’ urine following consumptionof the cider, but there was no evidence of quercetin, catechin, or epicatechinin the urine.

51

In another study involving human subjects, quercetin bioavailabilityfrom apples was only 30% of the bioavailability of quercetin from onions.

52

In this study, quercetin levels reached a peak after 2.5 hours in the plasma.The bioavailability differences between apples and onions most likely arefrom the differences in quercetin conjugates in the different foods. Onionscontain more quercetin aglycone and quercetin glucosides, whereas applestend to contain more quercetin monoglycosides and quercetin rutinoside,which may be less bioavailable. Our laboratory examined the bioavailabilityof both quercetin and quercetin-3-glucoside from apple peel extracts andonion extracts in Caco-2 cells.

53

Apple peel extracts contained no free quer-cetin, and no quercetin accumulation was seen in the Caco-2 cells followingincubation with apple peel extracts. Small amounts of quercetin-3-glucoside



were absorbed by the cells (4%). However, onions contain some free quer-cetin and greater amounts of quercetin glucosides, and the absorption ofquercetin into the Caco-2 cells from onion extracts was much greater thanfrom apple extracts.

53

The above results can be explained by the research examining quercetinand quercetin glycoside bioavailability. Walle et al.

54

found that, in ileostomyfluid, quercetin primarily existed as the aglycone form. They hypothesizedthat

β

-glucosidases hydrolyzed quercetin glucosides to quercetin, whichcould then be passively transported. In support of this theory, Day et al.

55

determined that quercetin glycosides were mainly deglycosylated by lactase-phlorizin hydrolase (LPH) before the aglycone then passed into the cell. Someintact glycoside transport by SGLT1 occurred and the glucosides were degly-cosylated within the cell by cytosolic

β

-glucosidase. They also found thatquercetin-3-glucoside appeared to utilize only the LPH pathway, not theSLGT1 transporter, but quercetin-4-glucoside used both pathways.

55

Applescontain a small amount of quercetin-3-glucoside that, following hydrolysisby LPH, would is available for uptake by intestinal cells. However, applesalso contain other conjugates such as quercetin rhamnosides, quercetin xylo-sides, and quercetin galactosides that are not easily hydrolyzed by LPH, andmost likely are not readily absorbed by small intestine cells. In comparison,the quercetin in onions is almost all in the form of quercetin glucosides andfree quercetin, making it more bioavailable to small intestine cells.

Some bacterial degradation of quercetin conjugates most likely occursin the human intestinal tract.

Enterococcus

casseliflavis

and

Eubacterium

ram-ulus

, microorganisms isolated from human feces, were both found to degradequercetin-3-glucoside as a carbon and energy source.

56

E.

casseliflavis

utilizedonly the sugar moiety of the glucoside, whereas

E.

ramulus

was also capableof degrading the aromatic ring system, with phloroglucinol produced as anintermediate.

56

In human ileostomy subjects, chlorogenic acid absorption was approxi-mately 33%, and only traces of chlorogenic acid were found in the urine.

57

The majority of chlorogenic acid reaches the large intestine and can bemetabolized by gut microflora. Gonthier et al.

58

found that rats fed chloro-genic acid excrete very little chlorogenic acid in their urine, but instead theyexcrete mainly microbially produced metabolites of chlorogenic acid, suchas hippuric acid and

m

-coumaric acid. A study by Olthof et al.

59

involvinghuman subjects showed that half of the ingested chlorogenic acid was con-verted to hippuric acid in the colon, most likely by microbial metabolism.

Catechin and epicatechin are both absorbed by small intestine epithelialcells.

60

In contrast to quercetin, epicatechin was not glucuronidated byhuman liver microsomes, nor was it glucuronidated by human small intes-tine or large intestine tissue.

61

Both liver and intestinal tissues contain uridinediphosphate-glucuronosyltransferases (UGTs) that are involved in the glu-curonidation of various other flavonoids. Epicatechin was found to be sul-fated by the human liver and intestinal cytosols, indicating that sulfation isthe major metabolic pathway for epicatechin metabolism.

61



The mechanisms in the bioavailability of specific phytochemicals arebecoming clearer as bioavailability research continues. In general, manyflavonoid aglycones tend to pass through the intestinal epithelial cells, wherethey are further conjugated. The flavonoid glycosides may be absorbed insmall amounts, but most absorption seems to occur following hydrolysis byintestinal hydrolases, such as LPH. Upon absorption, these compounds arealso conjugated. More research is needed to understand the bioavailabilityof compounds from whole foods. The effects of the food matrix, interactionsbetween compounds, digestion, and processing on the bioavailability ofphytochemicals are still unknown.

A good in vitro model would be beneficial in evaluating the bioavail-ability of phytochemicals from foods by offering a simple method to screenfor factors that may affect intestinal absorption of phytochemicals, such asthe food matrix, food processing, digestion, and interactions with otherfoods. Human and animal models can be expensive and time consuming,while a cell culture model allows for rapid, inexpensive screening. TheCaco-2 cell culture model has the potential to be a good model to measurethe bioavailability of antioxidants, such as carotenoids and flavonids, fromwhole foods.

53,62,63

6.5 Conclusion

Dietary modification by increasing the consumption of a wide variety offruits, vegetables, and whole grains daily is a practical strategy for consum-ers to optimize their health and reduce the risk of chronic diseases. Phy-tochemical extracts from fruits and vegetables have strong antioxidant andantiproliferative activities, and the majority of total antioxidant activity isfrom the combination of phytochemicals. The additive and synergistic effectsof phytochemicals in fruits and vegetables are responsible for their potentantioxidant and anticancer activities. The benefit of a diet rich in fruits,vegetables, and whole grains is attributed to the complex mixture of phy-tochemicals present in these foods. This explains why no single antioxidantcan replace the combination of natural phytochemicals in fruits and vegeta-bles. Therefore the evidence suggests that antioxidants are best acquiredthrough whole food consumption.

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11. Ames, B.N., Shigenaga, M.K., and Gold, L.S., DNA lesions, inducible DNArepair, and cell division: the three key factors in mutagenesis and carcinogen-esis, Environ. Health Perspect., 101(suppl. 5), 35, 1993.

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13. Vinson, J.A., Su, X., Zubik, L., and Bose, P., Phenol antioxidant quantity andquality in foods: fruits, J. Agric. Food Chem., 49, 5315, 2001.

14. Sun, J., Chu, Y.F., Wu, X., and Liu, R.H., Antioxidant and antiproliferativeactivities of fruits, J. Agric. Food Chem., 50, 7449, 2002.

15. Chu, Y.F., Sun, J., Wu, X., and Liu, R.H., Antioxidant and antiproliferativeactivities of vegetables, J. Agric. Food Chem., 50, 6910, 2002.

16. Adom, K.K. and Liu, R.H., Antioxidant activity of grains, J. Agric. Food Chem.,50, 6182, 2002.

17. Knekt, P., Jarvinen, R., Seppanen, R., Hellovaara, M., Teppo, L., Pukkala, E.,and Aromaa, A., Dietary flavonoids and the risk of lung cancer and othermalignant neoplasms, Am. J. Epidemiol., 146, 223, 1997.

18. Le Marchand, L., Murphy, S.P., Hankin, J.H., Wilkens, L.R., and Kolonel, L.N.,Intake of flavonoids and lung cancer, J. Natl. Cancer Inst., 92, 154, 2000.

19. Boyle, S.P., Dobson, V.L., Duthie, S.J., Kyle, J.A., and Collins, A.R., Absorptionand DNA protective effects of flavonoid glycosides from an onion meal, Eur.J. Nutr., 39, 213, 2000.

20. La Vecchia, C., Altieri, A., and Tavani, A., Vegetables, fruit, antioxidants andcancer: a review of Italian studies, Eur. J. Nutr., 40, 261, 2001.

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32. Knekt, P., Jarvinen, R., Reunanen, A., and Maatela, J., Flavonoid intake andcoronary mortality in Finland: a cohort study, BMJ, 312, 478, 1996.

33. Arai, Y., Watanabe, S., Kimira, M., Shimoi, K., Mochizuki, R., and Kinae, N.,Dietary intakes of flavonols, flavones and isoflavones by Japanese womenand the inverse correlation between quercetin intake and plasma LDL cho-lesterol concentration, J. Nutr., 131(9), 2243, 2000.

34. Joshipura, K.J., Hu, F.B., Manson, J.E., Stampfer, M.J., Rimm, E.B., Speizer,F.E., Colditz, G., Ascherio, A., Rosner, B., Spiegelman, D., and Willett, W.C.,The effect of fruit and vegetable intake on risk for coronary heart disease,Ann. Intern. Med., 134, 1106, 2001.

35. Liu, S., Manson, J.E., Lee, I.M., Cole, S.R., Hennekens, C.H., Willett, W.C., andBuring, J.E., Fruit and vegetable intake and risk of cardiovascular disease: theWomen’s Health Study, Am. J. Clin. Nutr., 72, 922, 2000.

36. Bazzano, L.A., He, J., Ogden, L.G., Loria, C.M., Vupputuri, S., Myers, L., andWhelton, P.K., Fruit and vegetable intake and risk of cardiovascular diseasein US adults: the first National Health and Nutrition Examination SurveyEpidemiologic Follow-up Study, Am. J. Clin. Nutr., 76, 93, 2002.

37. Berliner, J., Leitinger, N., Watson, A., Huber, J., Fogelman, A., and Navab, M.,Oxidized lipids in atherogenesis: formation, destruction and action, Thromb.Haemost., 78, 195, 1997.

38. Witztum, J.L. and Berliner, J.A., Oxidized phospholipids and isoprostanes inatherosclerosis, Curr. Opin. Lipidol., 9, 441, 1998.

39. Sanchez-Moreno, C., Jimenez-Escrig, A., and Saura-Calixto, F., Study oflow-density lipoprotein oxidizability indexes to measure the antioxidant activityof dietary polyphenols, Nutr. Res., 20, 941, 2000.

40. Chu, Y.F. and Liu, R.H., Cranberries inhibit LDL oxidation and induce LDLreceptor expression in hepatocytes, Life Sci., 77, 1892, 2005.

41. Ridker, P.M., Rifai, N., Rose, L., Buring, J.E., and Cook, N.R., Comparison ofC-reactive protein and low-density lipoprotein cholesterol levels in the pre-diction of first cardiovascular events, N. Engl. J. Med., 347, 1557, 2002.

42. Ridker, P.M., Clinical application of C-reactive protein for cardiovasculardisease detection and prevention, Circulation, 107, 363, 2003.

43. Libby, P., Ridker, P.M., and Maseri, A., Inflammation and atherosclerosis,Circulation, 105, 1135, 2002.



44. Gao, X., Bermudez, O.I., and Tucker, K.L., Plasma C-reactive protein andhomocysteine concentrations are related to frequent fruit and vegetable intakein Hispanic and non-Hispanic white elders, J. Nutr., 134, 913, 2004.

45. Eberhardt, M.V., Lee, C.Y., and Liu, R.H., Antioxidant activity of fresh apples,Nature, 405, 903, 2000.

46. Liu, R.H., Liu, J., and Chen, B., Apples prevent mammary tumors in rats,J. Agric. Food Chem., 53, 2341, 2005.

47. Adom, K.K., Sorrells, M.E., and Liu, R.H., Phytochemicals and antioxidantactivity of wheat varieties, J. Agric. Food Chem., 51, 7825, 2003.

48. Adom, K.K., Sorrells, M.E., and Liu, R.H., Phytochemicals and antioxidantactivity of milled fractions of different wheat varieties, J. Agric. Food Chem.,53, 2297, 2005.

49. Adom, K.K. and Liu, R.H., A rapid peroxylradical scavenging capacity (PSC)assay for assessing both hydrophilic and lipophilic antioxidants, J. Agric. FoodChem., 53, 6572, 2005.

50. Liu, R.H., Potential synergy of phytochemicals in cancer prevention: mecha-nism of action, J. Nutr., 134, 3479S, 2004.

51. Dupont, S., Bennett, R.N., Mellon, F.A., and Williamson, G., Polyphenols fromalcoholic apple cider are absorbed, metabolized, and excreted by humans,J. Nutr., 132, 172, 2002.

52. Hollman, P., van Trijp, J.M., Buysman, M.N., van der Gaag, M.S., Mengelers,M.J., de Vries, J.H., and Katan, M.B., Relative bioavailability of the variousantioxidant flavonoid quercetin from various foods in man, FEBS Lett., 418,152, 1997.

53. Boyer, J., Brown, D., and Liu, R.H., Uptake of quercetin and quercetin-3-glucoside from whole onions and apple peels by Caco-2 cell monolayers, J.Agric. Food Chem., 52, 7172, 2004.

54. Walle, T., Otake, Y., Walle, U.K., and Wilson, F.A., Quercetin glucosides arecompletely hydrolyzed in ileostomy patients before absorption, J. Nutr., 130,2658, 2000.

55. Day, A., Gee, J.M., DuPont, M.S., Johnson, I.T., and Williamson, G., Absorptionof quercetin-3-glucoside and quercetin-4-glucoside in the rat small intestine:the role of lactase phlorizin hydrolase and the sodium dependent glucosetransporter, Biochem. Pharmacol., 65, 119, 2003.

56. Schneider, H., Schwiertz, A., Collins, M.D., and Blaut, M., Anaerobic trans-formation of quercetin-3-glucoside by bacteria from the human intestinaltract, Arch. Microbiol., 171, 81, 1999.

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59. Olthof, M., Hollman, P.C., Buijsman, M.N., van Amelsvoort, J.M., and Katan,M.B., Chlorogenic acid, quercetin-3-rutinoside and black tea polyphenols areextensively metabolized in humans, J. Nutr., 133, 1806, 2003.

60. Spencer, J., Metabolism of tea flavonoids in the gastrointestinal tract, J. Nutr.,133, 3255S, 2003.

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62. Liu, C.-S., Glahn, R.P., and Liu, R.H., Assessment of carotenoid bioavailabilityof whole foods using a Caco-2 cell culture model coupled with an in vitrodigestion, J. Agric. Food Chem., 52, 4330, 2004.

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Part II

Quality and safety of berry fruit during postharvest handling and storage

5802_P002.fm Page 205 Monday, January 8, 2007 6:20 PM


207

chapter 7

Quality of berries associated with preharvest and postharvest conditions

Elizabeth Mitcham

Contents

7.1 Introduction ............................................................................................... 2077.2 Effect of harvest maturity and cultivar

on fruit quality .......................................................................................... 2087.2.1 Soluble solids, titratable acidity, and flavor ............................ 2097.2.2 Pigments ........................................................................................ 2107.2.3 Cell wall deterioration and softening....................................... 211

7.3 Changes after harvest............................................................................... 2127.3.1 Changes in anthocyanins ............................................................ 2127.3.2 Firmness......................................................................................... 2137.3.3 Soluble solids, titratable acidity, and sensory quality ........... 2137.3.4 Deterioration by pathogens........................................................ 2147.3.5 Nutritional loss during postharvest handling

and storage .................................................................................... 2157.3.6 Enhancing nutritional content after harvest............................ 220

References ........................................................................................................... 223

7.1 Introduction

Berry fruits are among the most perishable of fruit crops and must be han-dled carefully to ensure the highest postharvest quality when they reach theconsumer. Some berries have very high respiration rates and therefore apotentially short postharvest life. Many are fragile and easily bruised, requiring



careful handling during harvest, packaging, and transportation. The fruitsknown horticulturally as berries are not all true berries, botanically speaking.Blueberry is considered a false berry because it is berry-like, but it is derivedfrom an inferior ovary rather than a superior ovary.

1

The button on the endof the fruit is actually the calyx scar. Blackberry, boysenberry, and raspberryare not berries at all, but are aggregate drupes, and strawberry, also anaggregate fruit, is an achene fruit. Blackberry, raspberry, and boysenberryare composed of drupelets with a fleshy mesocarp and a lignified endocarpcontaining the true seed, all held together by a receptacle. Each drupelet issupplied with assimilate and water by a separate vascular supply and con-tains a single seed.

2

Raspberry druplets have fine hairs on the surface, whilethose of boysenberry do not. Boysenberry and blackberry retain their recep-tacle at harvest, while raspberry do not.

Raspberries and blackberries are some of the most perishable of the berryfruits, with very high respiration rates. Blueberries, cranberries, currants,and strawberries have lower respiration rates and longer storage life. Ethyleneproduction is generally low for this group of fruit, and many are nonclimac-teric.

3–5

One exception is blueberries, and there is some question about certaincultivars of blackberries.

6

Ease of detachment is often a good guide to properharvest maturity for blackberries, raspberries, and blueberries. The forcerequired to remove blackberry fruit from the pedicel declines during ripen-ing and varies among cultivars.

6

Ethylene accelerates abscission and pigmentchanges in raspberry

7

and blackberry

6

fruit.While ethylene does not appear to regulate ripening of the nonclimac-

teric berry fruits, auxin is proposed to be the primary hormone controllingfruit ripening in strawberries. Auxin is synthesized in the achenes, thetrue fruits embedded in the fruit surface (commonly considered the seeds),and stimulates initial fruit growth.

8

A gradual decline in auxin concen-trations in later stages of growth has been proposed to initiate ripening,

9

and auxin regulates transcription of many ripening-related genes in straw-berry.

10,11

It is not known if auxin plays a role in regulating ripening ofother berry fruit.

7.2 Effect of harvest maturity and cultivar on fruit quality

The characteristics and composition of ripe fruit are the result of biochemicaland physiological changes. Harvest of berries should be at near full ripestage, or the maximum ripeness stage that can be safely distributed to marketto maximize sweetness and flavor development, as berries do not accumulatestarch during development and therefore do not increase in soluble solids(an estimate of sugar content) after harvest.

4

Titratable acidity, largely madeup of citric acid in most berries, often decreases as the fruit ripens and afterharvest. This decrease can increase the perceived sweetness of berries orresult in bland flavor if the final concentrations are too low.


Chapter 7: Berry quality—preharvest and postharvest factors 209

7.2.1 Soluble solids, titratable acidity, and flavor

Maturity for strawberries is defined on the basis of skin color, with a require-ment for more than one-half or three-fourths of the surface being red or pink,depending on the U.S. grade. In California, fruit must have a minimum oftwo-thirds red or pink color. Strawberries ripen quickly on the plant.

12

Thereis an increase in soluble solids, total sugars, total ascorbic acid, pH, and watersoluble pectins, and decreases in acidity, total phenols, and activities ofpolyphenol oxidase and peroxidase in strawberries as they ripen.

13

Whenstrawberries are harvested with at least three-fourths red color, they continuetheir development and ripening during storage, developing the same pH,acidity, soluble solids, ascorbic acid, and total phenolics content during storageas the at-harvest levels present in fruit harvested at the full red color stage.

14

However, fruit harvested at half-color do not develop like those ripened inthe field. Volatile production of strawberries was the highest over a 10-daystorage period when fruit were picked with more red color.

15

Also,three-fourths red fruit were as firm and red after storage as the full red stagefruit were at harvest, thus strawberries harvested at three-fourths red stagecan be stored longer than strawberries harvested full red, while retaining bettercolor and firmness.

14

For strawberries, a minimum of 7% soluble solids and amaximum of 0.8% titratable acidity are recommended for best eating quality.

16

The harvesting of blueberries, blackberries, and raspberries is determinedby color development.

17

Fruit should be harvested with full or nearly full colordevelopment to maximize eating quality. Berries should also easily detachfrom the plant when ripe. Because fruit ripens on the plant at different times,plants must be harvested every few days, depending on the weather, to pre-vent overripening. As blueberries develop and ripen, there is an increase insoluble solids and a decrease in overall titratable acidity. Ripe berries willremain attached for several days to weeks and sugars will continue to accu-mulate. Blueberries exhibit increases in malic, chlorogenic, and phosphoricacid and decreases in citric and quinic acids during ripening.

18

The amount ofcitric acid in blueberries varies with the variety. Blueberry cultivar solublesolids content ranged from 9% to 11.5% and titratable acidity ranged from0.54 to 1.13 citric acid equivalents, resulting in a soluble solids:titratable acidityratio ranging from 10 to 19 among the 10 cultivars tested at harvest.

19

Raspberries also increase in soluble solids and decrease in titratable acidityas they develop and ripen.

4

Titratable acidity, soluble solids, and pH contributeto fruit flavor, and acidity and soluble solids vary greatly between cultivars.

Blackberries increase in soluble solids content and decrease in titratableacidity during ripening on the plant.

20,21

The increase in soluble solids occursparticularly between the 50% black and shiny black stage, and increasesduring storage due to weight loss.

22

There are greater changes in titratableacidity than soluble solids content as ripening progresses. Titratable aciditydecreases as much as 50% between the 50% black and shiny black stagesand 10% to 30% between the shiny black and dull black stages, dependingon the cultivar.

22

Following storage, titratable acidity decreases 10% to 30%,



depending on the stage at harvest. Sometimes titratable acidity increases invery ripe fruit due to weight loss in storage. Blackberries can develop a reddiscoloration after harvest. This is theorized to result from harvesting of lessmature fruit, resulting in less total pigment and a lower pH or differencesin the relative concentration of various pigments.

22

Harvest maturity is one of the main factors that determines nutritionalquality.

23

Freshly harvested fruit generally has a higher vitamin content thanstored products, as nutrients begin to be lost as soon as the fruit is har-vested.

23

Woods et al.

21

found significant variations among blackberry cul-tivars in their antioxidative properties (Trolox equivalent antioxidantcapacity [TEAC] values), and these were also influenced by harvest matu-rity. However, Perkins-Veazie and Collins

22

showed that while anthocyanincontent in blackberries differed among color stages, there was no differenceamong cultivars, indicating other compounds are involved in blackberryantioxidant activity. Antioxidant activity declined between the red and dullblack ripening stages of blackberry. Vitamin C content either declined orremained unchanged with ripening. Ascorbic acid content ranged from15.4 to 32.0 mg/100 g among five cultivars of raspberries.

24

In black raspberries,significant changes in the antioxidant capacity occur during the periodssurrounding peak ripeness, and this appears to be cultivar dependent.

25

Berry fruit is generally rich in phenolic acids.

26

The fruit phenolic contentcan be as high as 0.4% in some berries.

27

High sugars and high acids are required for good berry flavor.

28

Highacid with low sugar results in a tart berry, while high sugar and low acidresults in a bland taste. When both are low, the fruit is tasteless. Volatilecompounds are also important to aroma and flavor, especially ester com-pounds. Cultivar selection has a large influence on sensory quality. Goodcorrelations were found between sensory sourness and titratable acidity, totalphenolics, astringency, and sensory sweetness in strawberry cultivars.

29

Off-flavors were positively correlated with astringency and negatively cor-related with strawberry flavor intensity. Blueberry flavor appears to beclosely related with acid content, as high acid cultivars were also rated ashigh in blueberry flavor by sensory panelists and low-acid varieties had lowflavor scores.

30

Preharvest and postharvest factors can also influence fruitcomposition and quality, such as genetic and environmental factors (light,temperature, relative humidity, water supply). Sunny days and cool nightsproduce better flavored berries than cloudy, humid days and warm nights.Inadequate light intensity reduces ascorbic acid, pH, color, and solublesolids. Excess nitrogen decreases firmness, soluble solids, and flavor.

7.2.2 Pigments

Anthocyanins are the main types of pigment responsible for the color ofstrawberries, blueberries, raspberries, and blackberries. Anthocyanins maybe localized in the skin or in the entire fruit and are largely responsible forfruit color, although small amounts of carotenoids are also present. A high



correlation was found between objective skin color measurements (

L

*,

a

*,

b

*values) and anthocyanin content in red raspberries.

31

The anthocyanin con-tent varies between cultivars of raspberries and increases with fruit maturitybefore harvest and during storage.

5

As strawberries ripen, an increase inanthocyanin content is accompanied by decreases in firmness and chloro-phyll content. Strawberry fruit color develops quickly from first blush tofully red in only 24 to 36 hours.

12

The accumulation of anthocyanins instrawberries coincides with the induction of phenylalanine ammonia lyaseand uridine diphosphate glucose:flavonoid O

3

-glucosyltransferase enzymes.

8

The total anthocyanin content of blueberry cultivars ranged from 57 to208 absorbance units/g fresh weight (FW) at harvest.

9

7.2.3 Cell wall deterioration and softening

Berry fruits soften as they ripen. Fruit firmness in raspberries was shown tobe influenced by overall fruit size, hairiness, number and size of drupelets,and receptacle cavity size.

5

Extensive fruit softening occurred with the tran-sition in blueberry color from red to blue-red. A 50% red strawberry willlose 25% of its firmness in the 24 hours it takes to turn fully red and anadditional 15% if it remains on the plant another 24 hours.

12

When thestrawberry is removed from the plant, color and flavor development con-tinue, but there is little change in acid and sugar content or firmness. Therecan be considerable differences among cultivars in the firmness of ripe orpartially ripe berries.

28

Fruit textural changes result, at least in part, from changes in cell wallcomposition and architecture through the action of hydrolytic enzymes. Bothpolyuronides and hemicelluloses are important to the texture of straw-berries.

32

Pectins shift from insoluble to soluble during fruit ripening.

32,33

Cellulase activity increased sixfold in maturing and softening strawberries,and ethylene has no influence on cellulose levels.

34

Several pectin modify-ing genes have been cloned in strawberries, including pectatelyase,

35

endopolygalacturonase,

36

β

-galactosidase,

37

and pectin esterase.

38

In blue-berries, there was a 20% to 60% increase in water soluble pectin duringripening, while chelator soluble pectin increased slightly, and the contributionof pectin to the insoluble material in the fruit decreased twofold.

33

In highbushblueberries, the activity of pectin methylesterase peaked at the red color stage,before the peak in polygalacturonase activity which occurred at the blue-redstage.

39

Vicente

40

found that hemicellulose metabolism was important duringthe softening of blueberries. In the early stages, there were increases in thesolubilization of pectin and hemicellulose polymers, but without a decreasein polymer size. At later stages, there was a decrease in the size of hemicel-lulose polymers, but not those of pectin. Cell wall disassembly occurs inthree stages in boysenberries and raspberries.

40

In the earliest stage, therewere decreases in cellulose and solubilization of cross-linking glycans. In thesecond stage, there was a large increase in pectin solubilization and loss ofarabinose, but the pectin pieces remained large. In the final stage, there was



a large decrease in the size of the pectin molecules and a loss of galactose.The pectins of boysenberries, raspberries, and blueberries were found to berich in arabinose relative to galactose, in contrast to results for other fruitssuch as tomato and melon.

40

Cellulase activity, but not polygalacturonaseactivity, increased during the ripening of blackberries,

41

and therefore cellu-lase is considered the key enzyme responsible for softening in blackberryfruit. Cellulase releases pectins from the cell walls of ripening fruits, andthese soluble pectins also bind polyphenols, reducing astringency and mak-ing the fruit more palatable.

42

7.3 Changes after harvest

Fresh fruit is living tissue and continually changes after harvest. Suchchanges can only be slowed by judicious use of proper postharvest handlingprocedures, particularly the lowest safe storage temperature. Potential post-harvest life varies among berries, but is generally shorter than for manyother types of fruit. Respiration and ethylene production rates vary amongcultivars of red raspberry.

43

However, the higher respiration rates observedwith some cultivars of red raspberry were not associated with decreasedoverall storage life. The respiration rate of red raspberry was negativelycorrelated with percent changes in firmness during storage at 0

°

C and con-firmed that rapidly respiring cultivars ripen relatively slowly in prolongedstorage.

7.3.1 Changes in anthocyanins

Anthocyanin content of blueberries increased by 22% to 55% during 21 daysof storage at 5

°

C.

9

Sjulin and Robbins

44

observed darkening of red raspberriesduring storage. Color change occurred faster at higher storage temperatures,especially during the first 4 days of storage.

31

Storage of red raspberries for16 days at 0

°

C maintained fruit color (higher

a

* and

b

* values) better thanstorage at 5

°

C.

31

During 36 days of storage at 0

°

C, there was an increase inanthocyanin content and pH in red raspberries

43

and fruit became less redand bluer in color due to the increase in pH.

31,45

Cultivars generally main-tained their at-harvest rankings of quality even after cold storage.

43

Duringstorage of raspberries, color darkened and became more blue and less redas anthocyanins developed and pH increased.

45

This change occurred moreslowly at lower temperatures.

31

The rate of pH increase was different amongcultivars, while the rate of decrease in titratable acidity was the same amongred raspberry cultivars.

45

The amount of anthocyanins may be more impor-tant in visible color changes than shifts in acidity levels. Robbins and Moore

31

reported that cultivars going into storage with lighter, redder fruit, with littleblue, resulted in lighter, redder, less blue fruit after storage.

Strawberries also exhibited darkening after harvest, regardless of thematurity at harvest.

14,15,46

The ability of strawberries to develop full color instorage when harvested partially ripe varies with the cultivar. The development



of red color after harvest is also influenced by storage temperature.

47

Attemperatures of 24

°

C to 29

°

C, partially ripe strawberries developed full redcolor in 4 or 2 days, respectively, and at 18

°

C 90% color developed after4 days of storage. The after-storage hue of Chandler and Oso Grande straw-berries harvested at the three-fourths red stage was similar to that of fruitharvested at full red; however, the hue of Sweet Charlie strawberries har-vested at three-fourths red did not change significantly during storage.

14

Thecolor of strawberries tends to increase in chroma during fruit development.After storage, higher chroma values were observed in fruit that were har-vested with three-fourths red or full red color, indicating that the red colorwas more pure or vivid. The increase in red color during ripening of straw-berries on the plant or after harvest was accompanied by an increase in totalanthocyanins; however, total anthocyanin, cyanidin-3-glucoside, andpelargonidin-3-glucoside content were much lower in strawberries ripenedin cold storage compared with those ripened in the field.

14

7.3.2 Firmness

The firmness of strawberries decreased during ripening, in the field and afterharvest.

14

In Nunes et al.’s study,

14

the firmness of Chandler and SweetCharlie strawberries harvested full red did not change during storage,although the fruit appeared riper. Strawberries harvested at one-half orthree-fourths red color were not firmer than fruit harvested at full color after8 days of cold storage. During storage, changes in the rate and direction offirmness in red raspberries varied among the cultivars.

43,48

Robbins et al.

43

observed an increase in firmness of some red raspberry cultivars duringstorage, which they postulated was due to temporary calcium binding ofpectic polymers. Mitcham et al.

30

found increases in blueberry firmness dur-ing 3 weeks of cold storage in several cultivars, but Forney et al.

49

found nochange in firmness after 3 weeks of storage at 0

°

C or 7

°

C, but did findincreases in firmness after 6 and 9 weeks of storage in Burlington blueberries.The increase in firmness was temperature dependent, being greater whenfruit was held at 7

°

C than at 0

°

C. Associated with fruit firming was a cor-rugation and thickening of the epidermal and hypodermal cell walls.

50

Strawberries also exhibited an increase in fruit firmness as a result of expo-sure to 15% carbon dioxide (CO

2

) after harvest.

51

This effect was seen inmost, but not all cultivars tested.

7.3.3 Soluble solids, titratable acidity, and sensory quality

Changes in the balance between sugar and acid content during storage ofred raspberries

52,53

affect the sensory quality of the fruit.

54

The titratableacidity of red raspberries decreased, while soluble solids increased duringstorage at 0

°

C,

43

which was likely due to water loss. Burlington blueberriesdecreased in both soluble solids content and titratable acidity during storage.

49

The soluble solids content of several southern highbush blueberries did not



show significant changes during 21 days of storage at 5

°

C, except Climax,which showed a significant increase in soluble solids.

9

This increase couldnot be entirely accounted for by weight loss. Titratable acidity increased intwo blueberry cultivars, decreased in a third, and remained unchanged inseven others. The titratable acidity of strawberries decreased as fruit ripenedon the plant. This trend generally occurs as fruit continues to ripen duringstorage.

55

However, while Nunes et al.

14

observed a decrease in titratableacidity during storage of fruit harvested fully red, they observed an increasein titratable acidity in several cultivars during storage of strawberries har-vested at three-fourths red color or less.

14

The soluble solids content ofstrawberries increased as fruit ripened in the field and was correlated withred color development within a planting.

14

Strawberries showed increasesin soluble solids after harvest as well,

14

but soluble solids content was higherin fruit ripened in the field.

13,47

Also, postharvest increases in soluble solidsare probably not due to conversion of starch to sugars, since strawberriesaccumulate very little starch. The increase may be due to solubilization ofcell wall pectins increases in titratable acidity or increases in anthocyanins,all of which contribute to soluble solids, or due to dehydration.

Changes in the surface color of strawberries during ripening coincidedwith the production of volatiles.

15

When strawberries were harvested at redor pink color and stored at 15

°

C, volatiles production peaked after 4 daysand was eightfold higher in red fruit than pink. The postharvest life ofstrawberries based on sensory quality was shorter than that for appearancequality and varied among varieties.

29

The postharvest life based on sensoryquality was short in Aromas strawberries stored in air or 20% CO

2

at 5

°

Cand for Selva strawberries stored in 20% CO

2

. However, Selva and Diamontestrawberries retained their flavor quality during storage at 5

°

C in air and20% CO

2

, respectively. The differences in sensory quality were based on thelevel and proportion of flavor components (sugars, organic acids, and aromacompounds) and fermentative metabolites.

7.3.4 Deterioration by pathogens

Postharvest decay is a common cause of deterioration in berry fruit.

Botrytiscinerea

is one of the most common pathogens observed after harvest.

5 Inmany fruit, such postharvest decay results in large part from preharvestquiescent infections.56 Other infections occurred as a result of nesting;spreading of infections from fruit to fruit. All berry fruit have tender skinsand raspberry has a very fragile structure because of the open receptaclecavity that is easily injured, allowing invasion by pathogens. Blueberry cul-tivars vary in their susceptibility to postharvest decay.57 Colletotrichum acu-tatum, Colletotrichum gloeosporioides, and B. cinerea were the main rotsobserved. In general, late-season berries were more susceptible to decay thanfruit from earlier harvests.

To control decay, prompt and thorough cooling after harvest is critical,followed by storage at the lowest safe temperature to prevent deterioration



of the fruit. Rhizopus rot spores are present in the air and easily spread. Thefungus will not grow at temperatures lower than 5°C, and temperaturemanagement is the simplest method of control. However, the common pathogenB. cinerea continues to grow slowly at 0°C.

Modified atmosphere packaging for shipment with 15% to 20% CO2 and5% to 10% oxygen (O2) reduces the growth of B. cinerea and other pathogens(such as Rhizopus stolonifer) and reduces the respiration and softening ratesof strawberries, blueberries, raspberries, and blackberries, thereby extendingpostharvest life.58,59 Blueberries maintained acceptable firmness and decaylevels after 60 days of storage in 15% CO2.59 It is unknown what effect thisstorage regime had on fruit flavor. Storage of strawberries in elevated CO2

atmospheres reduced respiration rates during treatment and for a period oftime after treatment. The higher the CO2 concentration, the more pronouncedthe residual effects.60 Blueberries also showed a decrease in respiration ratewith higher CO2 concentrations.61

Whole-pallet covers and consumer packages for containment of themodified atmosphere are commonly used for berries. Prompt cooling mustbe done before applying atmosphere modification.58 Off-flavors can resultfrom high CO2 treatment, depending on the cultivar, temperature, and expo-sure time. A modified atmosphere containing 20% CO2 was effective insuppressing the growth of B. cinerea on strawberries and reducing nestingof infection from diseased to healthy berries.62 High CO2 has also been shownto control decay on blueberries49,63 and raspberries.5

Storage of strawberries in 20% CO2 resulted in off-flavor developmentafter 3 days.64 Off-flavors were due to increases in ethyl acetate and ethanol,but not acetaldehyde. Off-flavors were also noted when blueberries werestored in CO2 greater than 10% for several weeks.49 After 6 weeks in 25%CO2, stress-induced volatiles, ethanol, and ethyl acetate accumulated. It wasrecommended that blueberries be stored at 0°C with 10% CO2.49

Low-dose irradiation has been demonstrated to be effective for the con-trol of decay in strawberries, used either alone or in combination with ele-vated CO2 atmospheres,65 and is used commercially to a limited extent.Blackberries stored in up to 0.3 ppm ozone for 12 days at 2°C showedsuppressed fungal growth and better retention of fruit surface color.66 Con-tinuous ozone exposure at 0.1 ppm during storage at 2°C completely con-trolled decay by B. cinerea, while 20% of untreated blackberries decayed.66

Irradiation of blueberries with ultraviolet C (UV-C) light (up to 4000 J; 354 nm)provided a slight reduction in decay by Colletotrichum gloeosporioides.67

7.3.5 Nutritional loss during postharvest handling and storage

Water-soluble vitamins are more susceptible to postharvest losses thanfat-soluble vitamins, and vitamin C (ascorbic acid) is especially susceptibleto postharvest losses. Losses after harvest are promoted by longer storagetimes, higher temperatures, low relative humidity, and physical damage.Harvesting methods can cause physical injury and therefore can affect the



nutritional quality of the fruit. Delays from harvest to cooling or processingincrease the loss of nutrients. Strawberries lose vitamin C rapidly duringpostharvest handling if the fruit is capped (calyx removed) and all fruit losesvitamin C if bruised during harvest.68 The ascorbic acid content is relativelyhigh in strawberries (about 60 mg/100 g FW), depending on the cultivar,but water stress can induce ascorbic acid loss in strawberries.69 Wrappingthe fruit with plastic film reduced water loss and reduced ascorbic acid lossin strawberries.69,70 The effect was not due to modification of the atmosphere,as this was minimal. The total ascorbic acid content of the wrapped straw-berries changed little during 8 days of storage at 1°C or 10°C, while theunwrapped strawberries lost 20% to 30% of their ascorbic acid content overthe 8 days. The ascorbic acid content increases in strawberries as they ripen,particularly at the later stages of color development. Nunes et al.14 observedincreases in total ascorbic acid of as much as 21% in two strawberry cultivars.The increases were larger in fruit harvested less ripe, as the fruit continuedto ripen and synthesize ascorbic acid during storage. Nunes et al.14 proposedthat ascorbic acid might be synthesized from D-glucose during storage ofstrawberries.

As much as 100% of a nutrient can be lost between harvest and consumptionwithout detectable changes in flavor or texture.71 Losses vary by nutrienttype, type of fruit, physical damage, temperature, and storage environment.72

The ascorbic acid content in raspberries was unchanged or slightly higherafter storage in air, 15% CO2, or 31% CO2 for 7 days at 1.7°C.24 Postharvesthandling and storage operations that maintain the quality characteristics ofcolor, flavor, and texture, and control decay also reduce micronutrientlosses.73 However, large losses can occur in fruit stored for a long time. Forfresh-cut strawberries, the postcutting life based on visual quality endedbefore there was a significant loss of vitamin C.74

Nutrients in frozen, pasteurized, and sterilized products are relativelystable; however, large losses may occur before processing and during prep-aration for consumption. Vitamins in fruits are primarily destroyed by oxi-dation catalyzed by enzymes, light, prooxidant metals, active O2 species orother chemical oxidants.75 Most studies of vitamin loss in fruits and vegeta-bles have focused on ascorbic acid. In addition to being an essential nutrient,ascorbic acid has reducing and antioxidant properties. Both ascorbic acidand its oxidized product, dehydroascorbic acid (DHA), have similar vitamin Cactivity, but only ascorbic acid has reducing properties, which are importantfor inhibiting browning reactions. Vitamin C activity is irreversiblydestroyed when DHA is hydrolyzed. During storage, DHA increases at theexpense of ascorbic acid76 and may be responsible for more than 50% of thevitamin C activity in some fresh fruits and vegetables.

Storage in controlled or modified atmospheres can affect the loss ofnutrients such as ascorbic acid. Bangerth77 found reduced losses of ascorbicacid in apples and red currents stored in reduced O2 atmospheres and accel-erated ascorbic acid losses during storage in elevated CO2 atmospheres. Ingeneral, the lower the O2 concentration, the slower the loss of ascorbic acid;



however, the effect of elevated CO2 was variable, depending on the concen-tration, the storage temperature, and the type of fruit. Oxidation of ascorbicacid to DHA was reduced by modified atmosphere packaging in fresh-cutpeppers (Capsicum annum L.).78 The total ascorbate content in fresh-cut straw-berries was unaffected after storage for 7 days at 5°C under controlledatmospheres.74 Storage of strawberries in modified atmospheres using pack-age liners reduced the loss of ascorbic acid during 12 days of cold storage.79

Strawberries stored in controlled atmospheres with 5% O2 and 0.5% CO2

maintained higher levels of ascorbic acid than fruit stored in air; however,when the fruit was stored in controlled atmospheres with 15% CO2, therewas no difference in ascorbic acid content between the controlled atmosphereand air-stored fruit.79 Vitamin C content was reduced by high CO2 (10% to30%) storage, particularly in strawberries. In this study, reducing the O2

concentration in the storage atmosphere in the presence of high CO2 hadlittle effect on the vitamin C content. Ascorbic acid was decreased more byhigh CO2 than DHA.80 High CO2 may stimulate the oxidation of ascorbicacid by inducing injury and ethylene production, which increases ascorbateperoxidase activity.81

Loss of ascorbic acid was accelerated when fruit was transferred from acontrolled atmosphere in cold storage to retail storage conditions at 18°C.Washing intact or sliced strawberries in 100 ppm sodium hypochlorite caninduce significant oxidation of reduced ascorbic acid, but it did not affecttotal ascorbic acid content and therefore may not be nutritionally significant(Figure 7.1).74 Irradiation treatment results in negligible losses in niacin,thiamin, riboflavin, and β-carotene. Ascorbic acid is more radiosensitive andits losses range from 0 to 90%, depending on the commodity, cultivar, irra-diation dose and duration, and storage temperature.82 Irradiation of straw-berries with 1 to 3 kGy combined with refrigeration resulted in reducedlevels of total ascorbic acid and increased levels of DHA immediately aftertreatment and after 5 days of storage (Figure 7.2).83 After 10 days of storage,the levels of DHA were also decreased.

At present, there are very few data available describing the extent towhich postharvest practices and storage affect phytonutrient content.84 Thephenolic content of strawberries has shown inconsistent trends, in somecases increasing14,27 and in other cases decreasing or remaining unchanged.14

The anthocyanin content increased with time in storage for red raspberries45

and the rate of increase was similar among cultivars. There is a positivecorrelation between antioxidant activity and total phenolic or anthocyanincontent.85,86 The anthocyanin content in dull black blackberries decreasedafter 7 days of storage, but that in shiny black and 50% black fruit did notchange during storage.22 Anthocyanin synthesis continues in harvestedstrawberries and blueberries, even at low storage temperatures. However,the content of total anthocyanins, cyanidin-3-glucoside, and pelargonidin-3-glucoside was much lower in strawberries that ripened in cold storageinstead of in the field.14 The anthocyanin concentration in strawberriesincreased in both external and internal tissues during postharvest storage in



air at 5°C for 10 days, but the increase was lower in fruit stored in air enrichedwith 10% or 20% CO2.27 Anthocyanin levels in Aromas and Diamante straw-berries were not affected by storage duration or atmosphere, but in Selva,the accumulation of anthocyanins observed in air-stored fruit was inhibitedby CO2 (Figure 7.3). CO2 promotes anthocyanin loss in stored strawberries.87

Gil et al.87 found that controlled atmosphere storage decreased the anthocy-anin content of internal strawberry tissues, but did not affect the anthocyanincontent in external tissues. Storage of red raspberries in CO2 atmospheres(15% or 30% CO2) inhibited the increase in anthocyanin levels that occurredin air storage (Table 7.1).24 Heat treatments may reduce phenylalanine ammonialyase activity and anthocyanin accumulation in strawberries during storage.88

The total antioxidant capacity of blueberries (as measured using theferric reducing antioxidant capacity [FRAP]) method) was measured at har-vest and after storage. The total antioxidant capacity varied among thevarieties and decreased considerably during 1 month of storage.89 The fruitmaturity of blueberries had a significant effect on antioxidant activity, totalphenolic content, and anthocyanin content.90 During storage at 5°C, none of nineblueberry cultivars tested showed a significant decrease from the antioxidant

Figure 7.1 Effect of different washing treatments on the percentage of total ascorbateoxidized to dehydroascorbate in strawberries. Values followed by different lettersare significantly different, p < .05. Treatments: 1 = control, sliced without washing;2 = sliced, washed in water; 3 = sliced, washed in water with 100 ppm sodiumhypochlorite; 4 = washed in water with 100 ppm sodium hypochlorite, then sliced.(From Wright, K.P. and Kader, A.A., Effect of slicing and controlled-atmospherestorage on the ascorbate content and quality of strawberries and persimmons,Postharvest Biol. Technol., 10, 39, 1997, with permission.)

Treatment

0 1 2 3 4 50

1

2

% o

f L-a

bsor

bate

pre

sent

as

L-de

hydr

oasc

orba

t

3

4

5

6

7

8

2.3%a

5.1%b

7.4%c

6.5%bc



values at harvest until the end of the marketable life was reached for thatcultivar (3 to 7 weeks). One cultivar demonstrated a 29% increase in antiox-idant activity. Antioxidant activity, total phenolic content, and anthocyanincontent were strongly correlated with each other and moderately correlatedwith soluble solids content. The three factors showed no correlation withfirmness, percent severely bruised berries, or weight loss. Vaccinium corym-bosum cv. Bluecrop also showed a 1.2-fold increase in anthocyanin contentduring 8 days of storage at 20°C, which was accompanied by a 1.2-foldincrease in oxygen radical absorption capacity (ORAC), while storage at 0°C,10°C, or 30°C did not result in significant changes.91 Lowbush blueberryclones did not show a change in ORAC during 8 days of storage at 0°C,10°C, 20°C, or 30°C, despite a 27% loss in ascorbate at 20°C and 30°C.91 Kaltand McDonald92 reported a mean 18% increase in anthocyanin content inthree lowbush blueberry (Vaccinium angustifolium) cultivars, each harvestedat three different maturities, when stored at 1°C for 2 weeks. These results

Figure 7.2 Effect of irradiation dose and storage time on the total L-ascorbic acid andL-dehydroascorbic acid content of strawberry fruit. (Adapted from Graham, W.D.and Stevenson, M.H., Effect of irradiation on vitamin C content of strawberries andpotatoes in combination with storage and with further cooking in potatoes, J. Sci.Food Agric., 75, 371, 1997.)

Tot

al L

-Asc

orbi

c A

cid

0

10

20

30

40

50

60

70

80

90

Storage Days

0 5 10

L-de

hydr

oasc

orbi

c A

cid

0

2

4

6

8

10

120 kGy1 kGy2 kGy3 kGy



indicate that the antioxidant health benefits of blueberries can be retainedfor several weeks after harvest, as the antioxidant activity appears to bestable in blueberries. When blueberries are harvested immature (50% to 75%blue), the antioxidant activity increased during cold storage to significantlevels, although it did not reach the level found in fruit harvested mature.90

7.3.6 Enhancing nutritional content after harvest

Controlled stresses may be used as a tool to enhance the health benefits offruits after harvest.93 These stresses might include wounding, phytohormonetreatments, UV light exposure, other radiation treatments, controlled or mod-ified atmosphere exposure, and water stress. Kalt et al.91 showed that storingdifferent types of berries at temperatures greater than 0°C induced phenolicsynthesis and increased the fruit total antioxidant capacity. Studies withblack raspberries showed that storage of fruit at higher temperatures (up to28°C) increased the level of bioactive compounds (such as anthocyanins) andantioxidant capacity, but the increase may have been due to moisture lossand metabolism of sugars.94 Tissue deterioration, fungal decay, and moistureloss were promoted by higher temperatures, while storage at 4°C maintained

Figure 7.3 Total anthocyanin content (mean ± SD) of three strawberry cultivars storedat 5°C in air or air + 20% CO2. A = Aromas; D = Diamonte; S = Selva. (From Pelayo, C.,Ebeler, S.E., and Kader, A.A., Postharvest life and flavor quality of three strawberrycultivars kept at 5°C in air or air + 20 kPa CO2, Postharvest Biol. Technol., 27, 171, 2003,with permission.)

Days at 5°C

0 2 4 6 8 10

Pel

argo

nidi

n-3-

gluc

osid

e (m

g L−

1 )

50

100

150

200

A,AirA, Air+20kPaCO2S,AirS,Air+20kPaCO2D,AirD,Air+20kPaCO2


Chapter 7: Berry quality—preharvest and postharvest factors 221Ta

ble

7.1

Eff

ects

of

Cul

tiva

r an

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ond

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and

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cit

ric

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nsN

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the levels of bioactive compounds and antioxidant capacity present at har-vest and prolonged the shelf life of the fruit.

Treatment of strawberries after harvest with methyl jasmonate (22.4 mg/l)or ethanol vapors (400 µl/l) increased the antioxidant capacity of the fruitduring storage at 7.5°C, and the combination treatment had the highestantioxidant capacity, total phenolics (Figure 7.4), and anthocyanins.95 Thesetreatments also maintained fruit quality and reduced fungal decay duringstorage.

Figure 7.4 Effect of ethanol, methyl jasmonate and their combination on (a) totalantioxidant capacity and (b) total phenolic compounds in Allstar strawberries after12 days storage at 7.5°C. (Adapted from Ayala-Zavala, J.F., Wang, S.Y., Wang, C.Y.,and Gonzalez-Aguilar, G.A., Methyl jasmonate in conjunction with ethanol treatmentincreases antioxidant capacity, volatile compounds and postharvest life of strawberryfruit, Eur. Food Res. Technol., 221, 731, 2005.)

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Not all of the health-promoting properties of berries are best maintainedor maximized under optimal conditions during storage. It appears that abalance must be maintained between optimizing storage life and qualityafter storage and maintaining or inducing maximum nutritional quality.Postharvest treatments and storage regimes must be reevaluated if the goalis to maximize nutritional quality.

References1. Rieger, M., Fruit crop home page, http://www.uga.edu/fruit, 2005.2. Iannetta, P.P.M., van den Berg, J., Wheatley, R.E., McNicol, R.J., and Davies,

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46. Sacks, E.J. and Shaw, D.V., Color change in fresh strawberry fruit of sevengenotypes stored at 0°C, HortScience, 28, 209, 1993.

47. Austin, M.E., Shutak, V.G., and Christopher, E.P., Color changes in harvestedstrawberry fruit, J. Am. Soc. Hort. Sci., 75, 382, 1960.

48. Sjulin, T.M. and Robbins, J., Progress in extending raspberry shelf life: freshmarket studies of red raspberries, in Proceedings of the 74th Annual Meeting ofthe Western Washington Horticultural Association, Western Washington Horti-cultural Association, Mount Vernon, WA, 1984, p. 96.

49. Forney, C.F., Jordan, M.A. and Nicholas, K.U.K.G., Effect of CO2 on physical,chemical and quality changes in ‘Burlington’ blueberries, Acta Hort. (ISHS),600, 587, 2003.

50. Allan-Wojtas, P.M., Forney, C.F., Carbyn, S.E., and Nicholas, K.U.K.G., Micro-structural indicators of quality-related characteristics of blueberries—anintegrated approach, Lebensm. - Wiss. Technol., 34, 23, 2001.

51. Smith, R.B. and Skog, L.J., Postharvest carbon dioxide treatment enhancesfirmness of several cultivars of strawberry, HortScience, 27, 420, 1992.

52. Sjulin, T.M. and Robbins, J.A., Effects of maturity, harvest date and storagetime of postharvest quality of red raspberry fruit, J. Am. Soc. Hort. Sci.,112, 481, 1987.

53. Varseveld, G.W. and Richardson, D.G. 1980. Evaluation of storage and processingquality of mechanically and hand-harvested Rubus spp. fruit, Acta Hort. (ISHS),112, 265, 1980.

54. Nestby, R., Soluble solids and titratable acid in berries of cultivars and crosspopulations of raspberries, Meld. Norg. LandbrHøgsk., 57, 1, 1978.

55. Woodward, J.R., Physical and chemical changes in developing strawberryfruits, J. Sci. Food Agric., 23, 465, 1972.



56. Sommer, N.F., Fortlage, R.F., Mitchell, F.G., and Maxie, E.C., Reduction ofpostharvest losses of strawberry fruits from gray mold, J. Am. Soc. Hort. Sci.,98, 285, 1973.

57. Smith, B.J., Magee, J.B., and Gupton, C.L., Susceptibility of rabbiteye blueberrycultivars to postharvest diseases, Plant Dis., 80, 215, 1996.

58. Mitchell, F.G., Mitcham, E., Thompson, J.F., and Welch, N., Handling straw-berries for fresh market, Publication 2442, Postharvest Technology Researchand Information Center, University of California–Davis, Davis, CA, 1996.

59. Luchsinger, L., Villalobos, A., and Lizana, A., Effect of controlled atmospherein postharvest life of ‘Elliot’ blueberry, HortScience, 41, 1044, 2006.

60. Li, C. and Kader, A.A., Residual effects of controlled atmospheres on post-harvest physiology and quality of strawberries, J. Am. Soc. Hort. Sci., 114, 629,1989.

61. Song, Y., Ki, H.K., and Yam, K.L., Respiration rate of blueberry in modifiedatmosphere at various temperatures, J. Am. Soc. Hort. Sci., 117, 925, 1992.

62. El-Kazzaz, M.K., Sommer, N.F., and Fortlage, R.J., Effect of different atmo-spheres on postharvest decay and quality of fresh strawberries, Phytopathology,73, 282, 1983.

63. Ceponis, M.J. and Cappellini, R.A., Reducing decay in fresh blueberries withcontrolled atmospheres, HortScience, 20, 228, 1985.

64. Larsen, M. and Watkins, C.B. Firmness and concentrations of acetaldehyde,ethyl acetate and ethanol in strawberries stored in controlled and modifiedatmospheres, Postharvest Biol. Technol., 5, 39, 1995.

65. Brecht, J.K., Sargent, S.A., Bartz, J.A., Chau, K.V., and Emond, J.P., Irradiationplus modified atmosphere for storage of strawberries, Proc. Fla. State Hort.Soc., 105, 97, 1992.

66. Barth, M.M., Zhou, C., Mercier, J., and Payne, F.A., Ozone storage effects onanthocyanin content and fungal growth in blackberries, J. Food Sci., 60, 1286, 1995.

67. Perkins-Veazie, P. and Collins, J., UVC light treatment reduces decay of blue-berries, HortScience, 41, 1043, 2006.

68. Ezell, B.D., Darrow, G.M., Wilcox, M.S., and Scott, D.H., Ascorbic acid contentof strawberries, Food Res., 12, 510, 1947.

69. Nunes, M.C.N., Brecht, J.K., Morais, A.M., and Sargent, S.A., Controllingtemperature and water loss to maintain ascorbic acid in strawberries duringpostharvest handling, J. Food Sci., 63, 1033, 1998.

70. Lee, S.K. and Kader, A.A., Preharvest and postharvest factors influencingvitamin C content of horticultural crops, Postharvest Biol. Technol., 20, 207,2000.

71. Buescher, R., Howard, L., and Dexter, P., Postharvest enhancement of fruitsand vegetables for improved human health, HortScience, 34, 1167, 1999.

72. Shewfelt, R., Sources of variation in the nutrient content of agricultural com-modities from the farm to the consumer, J. Food Qual., 13, 37, 1990.

73. Clydesdale, F.M., Minerals: Their chemistry and fate in food, in Trace Mineralsin Food, Smith, K., Ed., Marcel Dekker, New York, 1988, p. 57.

74. Wright, K.P. and Kader, A.A., Effect of slicing and controlled-atmospherestorage on the ascorbate content and quality of strawberries and persimmons,Postharvest Biol. Technol., 10, 39, 1997.

75. Gregory, J., Vitamins, in Food Chemistry, Fennema, O., Ed., Marcel Dekker,New York, 1996, p. 531.



76. Wills, R., Wimalasiri, P., and Greenfield, H., Dehydroascorbic acid levels infresh fruit and vegetables in relation to total vitamin C activity, J. Agric. FoodChem., 32, 836, 1984.

77. Bangerth, F., The effect of different partial pressures of CO2, C2H4, and O2 inthe storage atmosphere on the ascorbic acid content of fruits and vegetables,Qual. Plant., 27, 125, 1977 [in German with English summary].

78. Howard, L.R. and Hernandez-Brenes, C., Antioxidant content and marketquality of jalapeno pepper rings as affected by minimal processing and mod-ified atmosphere packaging, J. Food Qual., 21, 317, 1998.

79. Vinokur, Y., Rodov, V., and Horev, B., Effect of postharvest factors on thecontent of ascorbic acid in Israeli varieties of strawberry, Acta Hort. (ISHS),567, 763, 2002.

80. Agar, I.T., Streif, J., and Bangerth, F., Effect of high CO2 and controlled atmo-sphere on the ascorbic and dehydroascorbic acid content of some berry fruits,Postharvest Biol. Technol., 11, 47, 1997.

81. Mehlhorn, H., Ethylene-promoted ascorbate peroxidase activity protectsplants against hydrogen peroxide, ozone and paraquat, Plant Cell Environ.,13, 971, 1990.

82. Maxie, E.C. and Abdel-Kader, A.S., Food irradiation—physiology of fruits asrelated to feasibility of the technology, Adv. Food Res., 15, 105, 1966.

83. Graham, W.D. and Stevenson, M.H., Effect of irradiation on vitamin C contentof strawberries and potatoes in combination with storage and with furthercooking in potatoes, J. Sci. Food Agric., 75, 371, 1997.

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86. Wang, S.Y., and Lin, H.S., Antioxidant activity in fruits and leaves of black-berry, raspberry, and strawberry varies with cultivar and developmental stag-es, J. Agric. Food Chem., 48, 140, 2000.

87. Gil, M.I., Holcroft, D.M., and Kader, A.A., Changes in strawberry anthocya-nins and other polyphenols in response to carbon dioxide treatments, J. Agric.Food Chem., 45, 1662, 1997.

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89. Remberg, S.F., Haffner, K., and Blomhoff, R., Total antioxidant capacity andother quality criteria in blueberries cvs ‘Bluecrop,’ ‘Hardyblue,’ ‘Patriot,’‘Putte,’ and ‘Aron’ after storage in cold store and controlled atmosphere, ActaHort. (ISHS), 600, 595, 2003.

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93. Cisneros-Zevallos, L., The use of controlled postharvest abiotic stresses as atool for enhancing the nutraceutrical content and adding-value of fresh fruitsand vegetables, J. Food Sci., 68, 1560, 2003.

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229

chapter 8

Microbial safety concerns of berry fruit

Mark A. Daeschel and Pathima Udompijitkul

Contents

8.1 Introduction ................................................................................................2308.1.1 Historical safety record and potential safety concerns...........2308.1.2 Microbial safety concerns of berries ..........................................2328.1.3 Potential sources of contamination of berries ..........................239

8.2 Food safety strategies and programs .....................................................2408.3 Specific strategies for ensuring microbial safety of berries ................242

8.3.1 Preharvest strategies .....................................................................2428.3.2 The safe harvesting of berries.....................................................2438.3.3 Processing safe berry products ...................................................246

8.4 Ensuring microbial safety of berries after production and processing............................................................................................2468.4.1 Transportation and distribution..................................................2468.4.2 Direct sales .....................................................................................2488.4.3 Retail handling ..............................................................................2488.4.4 The role of consumers in ensuring safety.................................249

8.5 Intervention technologies for ensuring microbial safety of berries......................................................................................................2508.5.1 Temperature control......................................................................2518.5.2 Surface disinfectants .....................................................................2518.5.3 Low-dose irradiation ....................................................................2528.5.4 Biocontrol........................................................................................253

8.6 Conclusion...................................................................................................254References.............................................................................................................255



8.1 Introduction

8.1.1 Historical safety record and potential safety concerns

The per capita consumption of fresh fruits and vegetables continues toincrease as a result of unprecedented availability and irrefutable evidencethat fresh produce is a primary component in maintaining a healthy lifestyle.Furthermore, the rich diversity of fresh plant foods in terms of flavors,textures, and colors provides satisfaction on many levels. Produce, while onits journey from the farm production site to its final consumer destination,will encounter a variety of environments and thus potential impacts onquality and safety. It is a paramount responsibility of all those involved inthe fresh produce business to protect these foods from processes and situationsthat may compromise safety. We are all custodians of our produce and mustbe vigilant in preventing contamination with physical, chemical, and biologicalhazards. In our quest for novel, exciting, more nutritious, and more convenientfresh foods, we must be on guard that we are not compromising heretoforeimpassable hurdles to contamination. It is only through effective collabora-tive efforts of industry, government, academia, and consumer education thatwe will minimize the threat of contamination of fresh produce. These foodsare perhaps the most worrisome in terms of food safety because of theminimal processing they receive. In fact, it is their most desirable consumercharacteristics of being fresh and unprocessed that provides the greatestopportunity for contamination to persist through the chain of distribution.Not all fresh plant foods are equal in terms of their ability to serve as sourcesof contamination. Certainly plant foods harvested directly from the groundmay be more prone to physical, chemical, and microbial hazards, while thosethat have a natural protective barrier such as a peel or skin (oranges, bananas)that is removed just prior to consumption present fewer safety problems.During the writing of this chapter, a nationwide outbreak occurred of

Escher-ichia coli

associated with bagged spinach. The U.S. Food and Drug Admin-istration (FDA) issued a warning to consumers not to buy bagged spinach.Sales and distribution of all bagged salad-type produce plummeted over-night. Leafy vegetables such as spinach and lettuce have been involved inseveral microbial contamination problems. The relatively high surface areaof these vegetables, coupled with intensive agricultural practices, the dislo-cation and cutting of the leaves from the plant, and sorting, cleaning, andwashing procedures have been suggested as opportunities for microbialcontamination. Some fruits and vegetables have very hydrophobic smoothsurfaces that tend to limit microbial adhesion while others have acidic inte-riors that limit the growth of potential pathogens.

In this chapter, we will focus on reviewing the microbial safety historyof berry fruits, the potential safety issues with these foods, and how producers,processors, distributors, and consumers can all help in preventing thesedesirable products from becoming a liability to human safety. Berry fruitsand products derived from them have in general enjoyed a safe record ofconsumption and have not been implicated as a significant source of microbial


Chapter 8: Microbial safety concerns of berry fruit 231

pathogen contamination. Nonetheless, the record is not spotless and micro-organisms have a way of appearing where we least expect them. Whereappropriate, we will discuss the scientific literature that has addressedmicrobial contamination of other fruits and vegetables and point out obser-vations that are relevant to safe berry fruit production and processing.

Fresh fruits and vegetables are important for the health and well-beingof the American consumer. In recent years, several outbreaks of foodborneillness have been associated with the consumption of both domestic andimported fresh fruits and vegetables.

1–3

It has also been recognized thatnonpasteurized fresh fruit juice can act as a vector for infectious disease.

4

Most troublesome is the observation that serious foodborne pathogens, suchas

E. coli

and

Salmonella

sp. are able to persist in the acidic environment offruit juices such as apple and orange.

5

Until recently, it was widely acceptedthat most low pH, high acid foods such as fruit were of minimal concern forfood poisoning outbreaks. However, the appearance of acid-resistant strainsof pathogens in our food supply has prompted a reexamination of how freshfruits are grown, harvested, stored, and processed. The FDA has taken aleadership role and has provided a guidance document for industry entitled“Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits andVegetables.”

6

A warning label is now required for nonpasteurized fruitjuices.

6

Recently the FDA issued its request on the application of its HazardAnalysis and Critical Control Point (HACCP) program for juice products toensure safety and sanitary processing of fruit and vegetable juices. Deadlinesfor compliance are January 22, 2002, for large businesses; January 21, 2003,for small businesses; and January 20, 2004, for very small businesses.

Microbial contamination of food is a serious problem that has come tothe forefront of the American consciousness with respect to purchases offresh and processed food. A complex array of factors, including emergingpathogen detection, centralization of food processing operations, and con-sumer demand for fresh and minimally processed products, now interact,thereby potentially compromising the safety of our food supply. Researchand reported foodborne outbreaks have indicated that fresh produce andjuices can serve as vectors for infectious diseases.

5,7–9

Table 8.1 lists thereported foodborne outbreaks linked to unpasteurized juices and ciders since1990. Table 8.2 gives examples of reported outbreaks of foodborne parasiticdisease associated with raw berries. Table 8.3 provides recall data on con-taminated berry juices.

10

Since 1997, the federal response has been guidedby what is known as the President’s Food Safety Initiative. Accordingly,Congress has allocated resources to the U.S. Department of Agriculture(USDA) and FDA to develop programs to enhance food safety. A subpart ofthe program, entitled

“The Produce Safety Initiative,” focuses on the safetyof imported and domestic fruits and vegetables. It has become apparent thaton the one hand, American consumers demand safe food, while on the other,they want products that are fresh, nutritious, and devoid of chemical preser-vatives. Thus the challenge is to provide safe foods that are attractive to theconsumer. This is an achievable goal, but only if there exists an understanding



of how foodborne pathogens enter the production/processing stream andwhat parameters dictate their survival.

Oregon, Washington, and Idaho are the nation’s major producers ofberry crops, including

b

lueberries, boysenberries, blackberries, red raspber-ries, and strawberries. Major berry products include fresh fruit, frozen fruit,juice, concentrate, and puree. Berries are a significant agricultural commod-ity in the Northwest. In Oregon,

11

the production values of strawberries,raspberries (including red and black raspberries), blueberries, and blackber-ries (including Evergreen and Marion blackberries) in 2005 were $15.68,$17.62, $30.43, and $22.69 million, respectively. The total caneberry produc-tion value in 2005 was $53.62 million. In the United States, the total utilizedproduction value of berries (including blackberries, blueberries, raspberries,boysenberries, loganberries, and strawberries) was about $0.1 billion.

12

8.1.2 Microbial safety concerns of berries

Berries are densely cultivated and are constantly exposed to soils, irrigationwater, and human contact. Current production practices were not designedto curtail potential pathogen contamination. Most disturbing is the observa-tion that

E. coli

O157:H7 can survive in cow manure-amended soil for morethan 6 months under dry conditions.

13

A review of the literature pertaining

Table 8.1

Reported Foodborne Outbreaks Linked to Unpasteurized Juice/Cider

Since 1990

Year Product Pathogen LocationNumber of cases

1991 Apple cider

Escherichia coli

O157:H7 Massachusetts 231993 Apple cider

Cryptosporidium parvum

Maine 1601995 Orange juice

Salmonella

sp. Florida 631996 Apple cider

E. coli

O157:H7 Connecticut 101996

a

Apple cider

E. coli

O157:H7 Western United States and Canada

66

1996 Apple cider

E. coli

O157:H7 Washington 21996 Apple cider

C. parvum

New York 311998

b

Apple cider

E. coli

O157:H7 Ontario 141999 Orange juice

Salmonella anatum

Florida 41999 Apple cider

E. coli

O157:H7 Oklahoma 71999 Orange juice

Salmonella muenchen

20 states and 3 Canadian provinces

423

2000 Orange juice

Salmonella enteritidis

Six western states

88

a

Unpasteurized juice from California was involved. Fourteen of the 66 people affected werefrom British Columbia. One child died in the USA.

b

Local health officials identified one batch of noncommercial, custom-pressed apple cider asthe most likely source (Health Canada

70

).



Tabl

e 8.

2

Exa

mpl

es o

f R

epor

ted

Out

brea

ks o

f Fo

odbo

rne

Para

siti

c D

isea

se A

ssoc

iate

d W

ith

Raw

Ber

ries

Path

ogen

Year

Loc

atio

nP

rod

uce

so

urc

eVe

nu

eTy

pe

of

berr

yN

o. o

f ca

ses

No.

of

dea

ths

Isol

ated

from

pro

du

ceC

omm

ents

Cyc

losp

ora

caye

tane

nsis

1995

Flor

ida

Gua

tem

ala

likel

yTw

o so

cial

ev

ents

Ras

pber

ries

lik

ely

870

No

Ras

pber

ries

fro

m b

oth

even

ts w

ere

purc

hase

d

from

sep

arat

e so

urce

s.

Two

clus

ters

rep

orte

d.

C. c

ayet

anen

sis

1996

20 U

.S. s

tate

s an

d 2

C

anad

ian

prov

ince

s

Gua

tem

ala

Var

ious

Ras

pber

ries

1465

0N

oPo

ssib

le c

onta

min

atio

n d

ue t

o fr

uit

spra

ying

w

ith

inse

ctic

ides

and

fu

ngic

ides

mix

ed w

ith

cont

amin

ated

wat

er.

C. c

ayet

anen

sis

1997

Mul

tist

ate

U.S

., an

d

Ont

ario

, C

anad

a

Gua

tem

ala

Var

ious

Ras

pber

ries

1012

0N

oSo

urce

of c

onta

min

atio

n un

know

n.

C. c

ayet

anen

sis

1998

Ont

ario

, C

anad

aG

uate

mal

aV

ario

usR

aspb

erri

es31

50

No

Sour

ce o

f con

tam

inat

ion

unkn

own.

C. c

ayet

anen

sis

1999

Ont

ario

, C

anad

aG

uate

mal

a lik

ely

Ban

quet

hall

Bla

ckbe

rrie

ssu

spec

ted

104

0N

RSo

urce

of c

onta

min

atio

n un

know

n.

Sour

ce:

Ad

apte

d f

rom

FD

A.

20

NR

, not

rep

orte

d.



to microbial hazards associated with fresh fruits and vegetables implicated

E. coli

O157:H7,

Salmonella

sp., and

Listeria monocytogenes

as bacterial patho-gens of significant concern in fresh produce safety.

14–16

Thus effective tech-nologies are needed to remove pathogens from fruits.

Fungal spoilage organisms can also compromise berry crops by decreasingthe fruit yield and quality.

Botrytis cinerea

has been isolated from the soils ofberry fields and is responsible for “gray mold” and postharvest damage ina wide range of fruits.

17,18

In addition,

Botrytis

has been classified as a humanallergen, since patients with sensitivities to mold display a high occurrenceof specific IgE antibodies to

Botrytis

.

19

Raw raspberries and possibly blackberries imported from Guatemalahave been associated with several large

Cyclospora cayetanensis

outbreaks(Table 8.2). The natural host for this parasite has not been identified; however,contaminated water used for pesticide application and poor harvesterhygiene have been suggested as the most likely routes of contamination.Frozen raspberries and frozen strawberries have been linked to several out-breaks of hepatitis A (Table 8.4). Hepatitis A, a virus spread by human feces,is thought to have contaminated the berries by contact with infected har-vesters or contaminated irrigation water. Frozen raspberries have also beenassociated with illness due to calicivirus, which is also spread throughhuman feces (Table 8.4).

Raw berries destined for the fresh market are harvested by hand andfield packed into retail containers without being washed. Strawberries des-tined for freezing are destemmed in the field, either using a metal device ora thumbnail. Berries that are to be processed are transported, usually atambient temperature, to a processing facility, where they are washed withpotable water or water containing an antimicrobial (e.g., chlorine), some-times sliced, and often mixed with up to 30% sucrose before freezing. Theextra human handling during harvesting and comingling in the processingfacility may explain the greater association of outbreaks with frozen berries.Also, viruses and parasites may actually be preserved by the freezing step.

To date, bacterial foodborne illnesses have not been directly linked tothe consumption of berries. However, reservoirs for enteric organisms suchas

Salmonella

and

E. coli

O157:H7 are similar to those of hepatitis A virus, sug-gesting that bacterial pathogens may also be occasional contaminants of berries.

Table 8.3

Recall Data on Contaminated Berry Juices

Year Food product Hazards Location

1999 Cranberry-raspberry drink

Mold contamination Southeast United States

1998 Raspberry drink Mold contamination Ten statesKiwi, lime, and grapefruit-flavored fruit juice beverage

Glass Multiple states

Source

: Anderson.

10



An FDA survey of imported produce found

Salmonella

in 1 of 143 samples ofstrawberries.

20

Recently we conducted preliminary experiments to assess the ability of

E. coli

O157:H7 and

Salmonella

sp. to persist in the acid environment of berryjuice and puree. As shown in Figure 8.1 and Figure 8.2, these pathogens wereable to survive in juice and puree at room temperature within the 5-day

Figure 8.1

Survival of

E. coli

O157:H7 in fruit juice and puree: Chardonnay grapejuice (

♦

); Pinot Noir grape juice (

■

); raspberry juice (

∆

); strawberry juice (x); raspberrypuree (

∗

); strawberry puree (

•

).

Figure 8.2

Survival of

Salmonella

sp. in fruit juice and puree: Chardonnay grape juice(

♦

); Pinot Noir grape juice (

■

); raspberry juice (

∆

); strawberry juice (x); raspberrypuree (

∗

); strawberry puree (

•

).

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5

Time (days)

Log

CF

U/m

l

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5

Time (days)

Log

CF

U/m

l



Tabl

e 8.

4

Exa

mpl

es o

f R

epor

ted

Out

brea

ks o

f Fo

odbo

rne

Vir

al D

isea

se A

ssoc

iate

d W

ith

Con

tam

inat

ed F

roze

n B

erri

es

Path

ogen

Year

Loc

atio

nP

rod

uce

so

urc

eVe

nu

eTy

pe

of b

erry

No.

of

case

sN

o. o

f d

eath

s

Isol

ated

fr

omp

rod

uce

Com

men

ts

Cal

iciv

irus

1997

Que

bec,

C

anad

aB

osni

aTw

o se

para

te

even

ts

Ras

pber

ries

(f

roze

n)>

200

0N

RLi

kely

con

tam

inat

ion

occu

rred

bef

ore

ship

ping

from

Bos

nia.

Cal

iciv

irus

1998

Finl

and

Impo

rted

Unk

now

nR

aspb

erri

es

(fro

zen)

>50

00

NR

Sour

ce o

f co

ntam

inat

ion

unkn

own.

Hep

atit

is A

1983

Scot

land

Scot

land

Hot

elR

aspb

erri

es

(fro

zen)

240

No

Susp

ecte

d r

aspb

erry

m

ouss

e pr

epar

ed

from

fro

zen

rasp

berr

ies.

Su

gges

ted

co

ntam

inat

ion

by

infe

cted

pic

ker(

s).

Hep

atit

is A

1988

Scot

land

Scot

land

Hom

eR

aspb

erri

es

(fro

zen)

50

No

Ras

pber

ries

fro

m a

sm

all f

arm

wer

e fr

ozen

at

hom

e.

Seve

ral p

icke

rs a

t the

fa

rm h

ad s

ympt

oms

of h

epat

itis

A.

Hep

atit

is A

1990

Geo

rgia

, M

onta

naC

alif

orni

a (1

988)

Scho

ol,

inst

itutio

n fo

r th

e d

isab

led

Stra

wbe

rrie

s (f

roze

n)15

(G

eorg

ia),

13 (M

isso

uri)

+

29

seco

ndar

y

0N

oF r

ozen

str

awbe

rrie

s us

ed to

mak

e d

esse

rt.

Em

pty

stra

wbe

rry

cont

aine

rs w

ith

sam

e lo

t nu

mbe

r ob

tain

ed

from

bot

h lo

cati

ons



impl

icat

ed s

ame

sour

ce. S

uspe

cted

co

ntam

inat

ion

by

infe

cted

pic

ker(

s).

Stra

wbe

rrie

s pi

cked

an

d st

ems r

emov

ed in

fie

ld. F

ruit

s was

hed

in

3 pp

m c

hlor

ine

prio

r to

slic

ing

and

fr

eezi

ng.

Hep

atit

is A

1997

Mul

tist

ate

U.S

.M

exic

oSc

hool

sSt

raw

berr

ies

(fro

zen)

242

+

14

susp

ect

0N

oFr

ozen

str

awbe

rrie

s an

d s

traw

berr

y sh

ortc

ake

wer

e im

plic

ated

in t

he

outb

reak

. Pos

sibl

e co

ntam

inat

ion

dur

ing

harv

esti

ng. H

and

w

ashi

ng in

the

fiel

d

limit

ed. S

tem

s re

mov

ed w

ith

finge

rnai

ls. E

vid

ence

su

gges

ted

low

leve

ls

of n

onun

ifor

m

cont

amin

atio

n.

NR

, not

rep

orte

d.

Sour

ce:

Ad

apte

d f

rom

FD

A.

11



experimental time frame. More long-term studies are currently in progress,including survival under refrigeration conditions.

Berry juice and puree are the traditional value-added products in theNorthwest and are defined as acid foods because their natural pH valuesare less than 4.6 (Table 8.5). Thus berry products are usually not regardedas potentially hazardous. However, it is observed that serious foodbornepathogens such as

E. coli

and

Salmonella

sp. are able to persist in the acidicenvironment of fruit juices such as apple and orange.

2,5

The appearance ofacid-resistant strains of pathogens in acid and acidified foods has prompteda reexamination of how fresh berries are grown, harvested, stored, andprocessed.

Considering the frequency of foodborne outbreaks associated with con-taminated apple ciders and the severity of the illnesses they caused, theFDA has recently concluded that there is a risk of serious illness fromconsuming juice products that have not been processed in a manner toproduce at least a 5 log

10

unit reduction in the pertinent target microorgan-ism for a period of at least as long as the shelf life of the products whenstored under normal and moderate abuse conditions. Such juices must bearthe following statement:

WARNING: This product has not been pasteurizedand, therefore, may contain harmful bacteria whichcan cause serious illness in children, the elderly, andpersons with weakened immune systems.

This requirement has prompted the development and validation of effi-cacious technologies that meet the FDA requirement, while having minimalimpact on the nutritional and sensory qualities of juice products.

21

Table 8.5

pH Values of Different Berries

and Their Products

Type of berries pH range

Blackberries, Washington 3.85–4.50Blueberries, Maine 3.12–3.33Blueberries, frozen 3.11–3.22Blueberries, Maine 3.12–3.33Blueberries, frozen 3.11–3.22Grapes, Oregon 2.95–3.60Raspberries 3.22–3.95Raspberries, New Jersey 3.50–3.82Raspberries, frozen 3.18–3.26Strawberries 3.00–3.90Strawberries, California 3.32–3.50Strawberries, frozen 3.21–3.32Strawberry jam 3.00–3.40



8.1.3 Potential sources of contaminations of berries

Food contamination may occur from microbiological, chemical, and phys-ical sources. Potential microbiological hazards are the primary safety issueof concern with fresh fruits. Contamination of fresh fruits by human patho-gens may occur at any stage during production, harvesting, handling,processing, storage, distribution, and consumer purchase. Poor agronomicpractices, use of contaminated water for crop irrigation, application ofimproperly composted animal manure as fertilizer, and lack of training offield workers on good personal hygiene can contribute significantly to thecontamination. Poor sanitation control during postharvest handling activ-ities is another mechanism for pathogen contamination of fresh fruits,including improperly cleaned bins, buckets, and trucks used for transpor-tation from the field to packinghouse, cross-contamination of dump tankwater, poor personal hygiene among employees, and improperly cleanedequipment.

Microbiological, physical, and chemical hazards may occur duringprocessing of fruits; for example, the microbiological risks of fresh-cutfruits in cutting or slicing operation. The internal tissue of fresh fruits isnormally protected from microbiological invasion by waxy outer skins orpeels. However, cutting circumvents this physical barrier, allowing juicesto leak from the inner tissues onto the surface of fruits. These juices containall the nutrients necessary to support and accelerate microbiologicalgrowth. These factors, plus an increase in the exposed surface area of cutfruit, can all contribute to greater microbiological populations, includinga potential increase in human pathogens levels. Hurst

22

summarized keymicrobiological risks of fresh-cut produce, including a lack of a kill stepin the process to eliminate potential human pathogens; some pathogens,such as

L. monocytogenes

are psychotrophic and can grow at refrigerationtemperatures. Longer shelf life (10 to 14 days) may provide sufficient timefor pathogen growth, whereas a modified atmosphere may suppress thegrowth of spoilage organisms, and certain pathogens (

L. monocytogenes

)survive and may actually thrive under these conditions. Moreover,fresh-cut fruits are consumed raw with few or no antimicrobial barriersin place.

Chemical and physical hazards may also become significant in additionto microbiological hazards. Chemical contaminants can be naturally presentin foods or can be introduced during processing when compounds generallyrecognized as safe (e.g., antioxidants, sulfiting agents, preservatives) are notused according to government regulatory guidelines. It is incumbent upon theprocessor to ensure that chemical compounds such as sanitizers and lubricantsare used with strict adherence to existing regulations and product specifica-tions. The good manufacturing practices (GMPs) mandate that potential con-taminating chemicals be physically segregated from foods or food ingredients.Physical contaminants can be defined as any material not normally found infood that can produce an injury or illness in the consumer. They can enter the



food supply through contaminated raw materials, faulty processing equip-ment, improper packaging, and poor employee hygiene practices. Examplesof physical hazards that can compromise food safety include metal fragments,gravel, plastic, glass particles, and jewelry; these hazards affect product safety.Prevention methods can rely on visual examination, frequent inspections ofequipment, and the use of metal and glass detectors.

8.2 Food safety strategies and programs

A strategy that prevents the initial microbial contamination of berries is saferthan relying on corrective actions after contamination has occurred. Becauseit is not practical to eliminate all potential hazards associated with freshproduce, berry producers and processors must rely on risk reduction ratherthan total risk elimination.

To minimize microbiological safety hazards during agricultural opera-tions, the FDA Center for Food Safety and Applied Nutrition (CFSAN)developed in 1998 the “Guide to Minimize Microbial Food Safety Hazardsfor Fresh Fruits and Vegetables.”

6

This publication addresses potential foodsafety issues associated with farmland, irrigation water, fertilizer usage andpesticide monitoring, harvest practices, field sanitation, and worker hygiene,and sets forth good agricultural practices (GAPs) for producers to ensurefood safety. It stresses prevention of contamination over corrective actionsonce contamination has occurred and establishes a format for developing asystem of accountability of sanitary practices at all levels of the agriculturaland packinghouse environment.

The GAPs can serve as guidance for farmers throughout the growth,harvesting, packing, and transportation phases of each berry crop. However,once the fruit has been transported from the field, other food safety protocolsmust be followed. The GMPs are described in the

Code of Federal Regulations

(CFR) section 21, part 110, and are required by law in the United States forall food manufacturing companies. The GMPs address four main areas offood processing, including the design of buildings and facilities to protectagainst product contamination, sanitation of equipment and utensils to pre-vent contaminants from being introduced into the food, personnel hygieneto protect adulteration of foods by food handlers, and process controls thatensure adequate food processing during production.

The most important issues that are addressed in the GAPs include

• Water• Manure and municipal biosolids• Worker health and hygiene• Sanitary facilities• Field/packing facility sanitation• Transportation/distribution• Consumer packaging• Traceback.



The GAPs focus on microbial hazards for fresh produce, on risk reduc-tion, not risk elimination, and provide broad, scientifically based principles.The guide is one of the first steps to improve the safety of fresh produce asit moves from farm to the table. At this point, they are guidelines that willeventually become enforceable regulations.

However, the GMPs are required by law (21 CFR 110) and apply to allfood manufacturing companies to ensure good food plant sanitation. Fur-ther processing and manufacturing into finished products in no wayexempts raw materials from the requirements of cleanliness and freedomfrom deleterious impurities. GMPs are prescribed for four main areas offood processing:

1. Personnel hygiene to prevent the spread of illness.2. Adequate buildings and facilities.3. Sanitary food contact surfaces (e.g., equipment and utensils).4. Process controls to prevent cross-contamination.

Sanitation standard operating procedures (SSOPs) focus more narrowlyon specific procedures that allow a fruit-processing plant to achieve sanitaryprocess control in its daily operations. SSOPs are mandatory for all food-processing plants (21 CFR 120.6) subject to the HACCP program. Althoughspecific protocols may vary from facility to facility, SSOPs provide specificstep-by-step procedures to ensure sanitary handling of foods. These docu-ments describe procedures for eight sanitation conditions:

1. Safety of water.2. Cleanliness of utensils and equipment.3. Prevention of cross-contamination.4. Hand washing and toilet facilities.5. Protection of food from contaminants.6. Labeling and storage of toxic compounds.7. Monitoring employee health.8. Pest control.

Specific sanitation procedures recommended for fresh-cut fruit and vegetableprocessing have been discussed by Hurst.

22

A more focused approach toward controlling food safety—HACCP—was developed by the FDA to establish safety standards throughout the foodindustry. The HACCP program is a structured approach to the identification,assessment of risk, and control of hazards associated with a food productionprocess or practice. It aims to identify possible problems before they occurand establish control measures at production stages that are critical to prod-uct safety. Design and implementation of the HACCP system involves sevenbasic principles or steps:

1. Identify possible food safety hazards.2. Determine critical control points.3. Establish preventive measures.4. Monitor the manufacturing process to detect hazards.



5. Plan corrective actions.6. Prepare a method to verify that the HACCP plan is working.7. Document the HACCP system by maintaining records.

The HACCP program is a proven, cost-effective method of maximizingfood safety because it focuses on hazard control at its source. It offers sys-tematic control by covering all aspects of production and handling from rawmaterials to consumer preparation. In the

Federal Register

of January 19, 2001,the FDA published final regulations to ensure the safe and sanitary process-ing of fruit and vegetable juices. These regulations mandate the applicationof HACCP principles to the processing of juices, including berry juice prod-ucts. Although HACCP is not mandatory for all food industries, it has beenembraced by the fresh-cut processing industry as a useful tool for imple-menting food safety practices in the production environment. The HACCPprogram is well suited to identify hazards, monitor production for adherenceto operational standards, and develop an effective record-keeping system ina fresh-cut produce facility. With close attention to prerequisite programs, aprocessor can implement HACCP to round out their food safety program.

In summary, utilizing the principles of GAPs and GMPs during growing,harvesting, washing, sorting, packing, and transporting of fresh fruits willminimize microbial food safety hazards. Developing specific step-by-stepSSOP protocols and implementing a HACCP program will further ensurethe safety of fresh and processed products from farm to market to consumer.

8.3 Specific strategies for ensuring microbial safetyof berries

8.3.1 Preharvest strategies

Bower et al.

23

discussed in a great detail the potential risks of contami-nation of berries during production and suggested strategies to reducethe risks. To prevent preharvest contamination of berries, a specific setof GAPs have to be developed. As described in Table 8.6, the GAPs beginby reviewing the history of the farmland to ensure that no prior land usehas compromised the microbial or chemical safety of the site. The adjacentland is also evaluated to verify that no contamination is being carried toproduce fields by water, wind, or vehicles. The purity of the water sourceis also important, since streams, reservoirs, and wells can spread micro-bial contaminants.

Fertilizer use and pesticide monitoring are also important components ofGAPs. Improperly composted manure can become a direct source of patho-gens for a berry crop. Contamination can also occur when crops are irrigatedwith equipment that was used to apply liquid manure. GAPs encourage rig-orous management techniques to ensure the proper application of organicfertilizers. Careful records must be maintained for all fertilizer applications,and only authorized pesticides and herbicides should be applied.



Good agricultural practices also stress field sanitation, including an effec-tive pest control program. Wildlife and domestic animals should always beexcluded from produce fields, and worker health should be monitored toprevent ill workers from contacting raw produce. To maintain workerhygiene, toilet facilities with hand-washing stations must be provided, aswell as potable water for drinking and hand washing.

8.3.2 The safe harvesting of berries

Bower et al.

23

note that the three key parts of a safe harvest system aresanitary harvest conditions, cooling berries right after harvest, and safehandling and storage practices.

Table 8.6

Preharvest Good Agricultural Practices for Berries

1. Site selection and adjacent land useTest for microbial/chemical hazards from prior use of farmland.Ensure that no contamination is carried by water, wind, or vehicles from adjacent land.Avoid fields that are susceptible to flooding.Use mulch to reduce contact between the soil and berries.

2. Purity of the water sourceEvaluate water for irrigation (since streams, reservoirs, wells, and public water systems can potentially spread contaminants).Periodically test water sources for microbes.Do not irrigate crops with equipment that has been used to apply liquid manure.

3. Fertilizer use and pesticide monitoringBe aware of the proper application of organic fertilizers.Follow rigorous management techniques for treating manure.Maintain careful records of all fertilizer applications.Use only authorized pesticides and herbicides.Apply all chemicals appropriately.

4. Wildlife, pest, and vermin controlMaintain an effective pest control programExclude wildlife and domestic animals from fields.Periodically verify that the pest control plan is working.

5. Worker hygiene and field sanitationDo not allow ill workers to contact raw produce.Supply potable water for drinking and hand washing.Provide toilet facilities with hand-washing stations.Follow local, state, and federal regulations for worker health.Establish a training program that covers worker sanitation.Protect harvest containers from contacting soil.

Source:

Adapted from Bower et al.

23



Most microbial contamination is on the surface of fresh produce, neces-sitating a washing step to reduce the possibility of foodborne illness beforesale. Washing also helps to prevent the spread of microorganisms from oneberry to the next. To decrease the possibility of waterborne contaminantscompromising the quality of the berries, it is essential to use potable waterwhenever there is water-produce contact. Approved sanitizers such as liquidchlorine, sodium hypochlorite, or calcium hypochlorite can help controlcontamination when produce is immersed in wash water. If a sanitizer suchas chlorine is added to the wash water (pH 6.0 to 7.0) to control bacteria,the concentration of free (unreacted) chlorine (100 to 150 ppm) should betested frequently.

Berries in the field can come in contact with soil, domestic and wildanimal feces, and poor quality water during harvest. Not all berries arecooled and washed after harvest (e.g., strawberries), thus increasing thepossibility of microbial contamination. To minimize this risk, clean palletsand sanitized containers should be available for freshly harvested berries,and care should be taken to ensure that the containers do not becomeexposed to soil and manure when produce is packed in the field. Employeesshould stand on any container where contaminated shoes can become avector. Good worker hygiene and field sanitation practices are also essen-tial. All workers who handle fresh produce should receive training on theimportance of good hygiene, including the necessity for effective handwashing.

When possible, harvesting of berries should be carried out at night orduring the early morning hours to minimize exposure to high daytimetemperatures. Freshly harvested berries should be held in the shade withadequate ventilation whenever possible. If berries are temporarily storedbeneath a tree for shade, the containers should be covered with clean, san-itized tarps to protect the berries from contamination by birds.

Water, ice, and forced air are among the methods devised to removefield heat from produce after harvesting, thereby slowing or inhibiting micro-organism growth and extending the shelf life of the produce. Systems thatutilize air cooling have the lowest risk of contamination during the coolingprocess; however, they can potentially transfer microorganism-containingdust particles and water droplets onto fresh produce. Cooling systems basedon water and ice have the greatest potential for contamination, even whenpotable water is used. The addition of chlorine (50 to 200 ppm) can helpcontrol bacteria; however, chlorine reacts with organic compounds and canrapidly lose its effectiveness. If water is used for cooling, the temperatureshould be greater than that of the produce to prevent the temperature dif-ference from pulling microorganisms from the surface of the fruit inwardwhere they cannot be easily removed.

23

Bacteria can rapidly multiply in areas where poor sanitation is prac-ticed. Harvest storage areas should be maintained in a clean, sanitary con-dition and containers should be cleaned and sanitized prior to the arrivalof fresh produce. Fresh berries should not be transported in trucks recently



used to haul animals or animal products without extensive cleaning andsanitation before loading.

Harvesting and packing operations should effectively clean and sanitizeall food-contact surfaces. This includes washing, grading, sorting, and packinglines, as well as equipment, floors, and drains, to prevent fresh produce frombecoming contaminated with pathogenic microorganisms.

Cross-contamination between raw and washed berries from sources suchas wash water, rinse water, ice, dust, equipment, utensils, and vehicles mustbe prevented. The presence of fecal coliforms can serve as an indicator ifcontaminants are suspected.

Figure 8.3

Flow diagram for berry juice production (adapted from Nagy et al.

71

).

Cooling

Receiving

Washing

Heating

Inspection

Roll – milling

Treatment with enzymes

Pressing

Centrifuging

Clarifying

Filtration

Blending correction

Deaeration

Pasteurization

Aseptic filling

Clear juice

Enzymes

Sugar, Water, Acids Concentrated flavor

Pectolytic enzymes

CCP 1

CCP 2

CCP 3



8.3.3 Processing safe berry products

The GAPs serve as guidance for fruit producers throughout the growth,harvesting, packing, and transportation of each berry crop. However, oncethe fruit has been transported from the field, other food safety protocols,including GMPs, SSOPs, and HACCP, must be followed. Bower et al.23 pro-vide detailed guidelines for implementing GMPs and SSOPs during variousberry processes. It is important to emphasize the HACCP program for berryjuice production. Processing of all juice products, including juice, concen-trate, and puree sold in the United States is subject to HACCP requirements.The HACCP system is structured to address food safety issues by monitoringcritical points in the manufacturing process to ensure that the final productis safe. Juice processors must operate under an approved HACCP plan toprevent their finished juice products from being labeled “adulterated.”

Good manufacturing practices and SSOPs are prerequisite programs forHACCP and should be documented and regularly audited along with theHACCP plan. Consequently it is not necessary to include specific sanitationprotocols in the HACCP plan. Factors that lead to spoilage or quality lossof the fruit, but do not affect the product’s safety, should be addressed inthe GMPs or SSOPs, and not in the HACCP plan.

The HACCP plan for fruit juice manufacturers contains a 5 log pathogenreduction step that is capable of preventing, reducing, or eliminating patho-genic microorganisms by 100,000-fold. This step must be implemented priorto the final fill and must be validated (21 CFR 120.24). Potential technologiesfor achieving a 5 log reduction include thermal processing, high hydrostaticprocessing, dense phase carbon dioxide pressure processing, and ultraviolet(UV) processing. Mandatory warning labels are required for juices (andbeverages that contain fruit juice) that do not contain a 5 log pathogenreduction step (21 CFR 101.17).

The guideline for preparing an HACCP plan for berry juice was devel-oped by Bower et al.23 Figure 8.3 shows an example of a berry juice processingflow diagram and three critical control points (CCPs) determined during theprocess.

8.4 Ensuring microbial safety of berries after production and processing

8.4.1 Transportation and distribution

Transportation systems for fresh produce can be classified into differentlevels, including transportation from the field to the cooler, packing facility,distribution and wholesale terminal markets, or retail centers. Microbialcross contamination may occur from other foods and nonfood sources andcontaminated surfaces during loading, unloading, storage, and transporta-tion operations. Therefore, the distribution and transportation conditions canhave profound effects on microbial safety. If these procedures are managedproperly, the risk of illness associated with microbial contamination in fresh



produce can be effectively reduced.24,25 Food safety during transportationand distribution can be enhanced by applying preventive methods such asgood sanitation practices and the HACCP program.26 This will ensure thatfood products that reach consumers are high quality and safe to eat.27

During distribution and transportation of fresh produce, loading dockworkers, truck drivers, and retail workers all share the responsibility inpreventing cross contamination and maintaining appropriate temperatures.25

Thus, an effective way to ensure safety from microbial food hazards duringtransportation can be achieved by an active and ongoing dialogue with respon-sible personnel so that an effective management program designed to deliversafe foods to consumer can be fully implemented.24,27 However, additionalmicrobiological and other safety assurance tests on products after transporta-tion may be necessary to compare obtained data with the results from pre-shipment to determine whether corrections are needed.26

Although recognizing that the transportation system is one of the impor-tant factors contributing to the safety of fresh produce and that effective,safe transport is an important part of the chain of custody, it is often over-looked.25 The following basic considerations should be applied in order toprevent microbial cross contamination and maintain the safety of berriesduring transportation and distribution:

• The sanitation condition of trucks and other carriers, loading equip-ment, cargo pallets, and load securing devices. This equipmentshould be evaluated for cleanliness, odors, and obvious dirt or debrisbefore the loading process and should be regularly washed and san-itized. The shipping record needs to be monitored periodically toprevent cross contamination from other food and nonfood products.Vehicles that have recently been used for transporting live animals,animal products, or other sources of pathogenic bacteria have to besanitized properly prior to loading fresh berries.24–26

• Proper air circulation. As fresh berries are regularly shipped in re-frigerated trailers, proper air circulation is critical to maintain thetemperature throughout the vehicle. With improper cooling, heatgenerated by product respiration, and heat absorbed from outsidethe vehicle results in an increase in product temperature to undesir-able levels, thus increasing the risk of foodborne illness and thechance of economic losses. To ensure adequate airflow, appropriateshipping containers, vehicles, loading patterns, and alignment ofvent holes in the containers are required.25,27,28 In addition, differenttypes and varieties of berries may require different optimum tem-peratures during transportation; delivery of mixed loads with incom-patible refrigeration requirements should be avoided.24

• Education of employers and employees on food safety. Despite thefact that many sources contribute to contamination of fresh berries,workers seem to be the most likely cause.29 Therefore, suitable personalhygienic practice is essential among all personnel who are responsiblefor every step in the transportation and distribution system.



• Physical damage of fresh berries. Physical damage encourages mi-croorganisms to invade fresh produce tissue, leading to accelerateddeterioration and an increased risk of illness from consumption ofinfectious produce. Hence, efforts to minimize physical damage duringdistribution and transportation are needed.

8.4.2 Direct sales

Direct farm sales and farmer’s markets have been a traditional way to linklocal food producers with consumers, while at the same time creating a senseof community and place. The U-pick farm operation is another avenue formarketing produce directly. The latter is especially popular for people inter-ested in obtaining fresh berry fruits such as blueberries, strawberries, andraspberries. For most U-pick consumers, it is viewed as a family outing, withseveral family members participating. Even though the chain of custody isshorter in this type of sale, common sense food safety measures should be inplace to limit the possibility of pathogen contamination.

Most, if not all, farmer’s markets are subject to inspection and licensingby local agencies to ensure food safety. At the U-pick farms, the owner/operator should follow these guidelines:

• Provide convenient, clean, well-maintained, and serviced toilet facil-ities in the fields.

• Encourage hand washing before picking. Supply liquid soap in dis-pensers, potable water, and single-use paper towels for hand washing.

• Fruit picked but left behind by customers should be discarded.• Prohibit customers from bringing pets into the fields.

8.4.3 Retail handling

Factors that contribute to the presence of pathogenic microorganisms onfresh produce during retail handling include cross contamination from otherfoods in the store, contamination from preparation and display areas, andimproper display temperature.30 Retail display cases must be clean and theproper refrigeration temperature must be maintained.25 The existence ofpathogenic microorganisms on retail food products was reported by Thun-berg et al.,31 who observed that several Listeria sp., including L. monocytoge-nes, an enterotoxigenic isolate of Staphylococcus sp., and a toxigenic speciesof Bacillus sp. were isolated from fresh produce displayed in a retail market.

The postharvest quality and microbial quality of fresh produce arestrongly influenced by temperature, relative humidity, and the compositionof the storage atmosphere.32 Temperature and relative humidity are set asa critical limit during transportation and storage for monitoring programsinvolved in the HACCP system. Fresh produce is perhaps exposed to thegreatest temperature abuse during retail handling. The combination of timeand temperature during holding and the relative perishability of each type ofproduce can contribute to temperature abuse at the retail level. The average



display temperatures of fresh produce are 7.6°C and 8.4°C in winter andsummer, respectively.33 While 4°C is the recommended temperature forstoring some retail produce commodities, there is the report that as muchas 90% of those products are stored above this temperature. The recom-mended optimum relative humidity for the storage of fresh strawberries,raspberries, blackberries, Logan blackberries, and dewberries is 85% to 90%.However, it is difficult to maintain such high relative humidity in a largestorage room.34,35

Beuchat36 estimated that the postharvest losses of fresh produce can be30% or more due to microbial spoilage. While the growth of saprophyticfungi, yeast, and bacteria contribute to spoilage of fresh produce,32 the controlof microbial proliferate during storage is essential.

In order to prolong shelf life, promote a fresher appearance, and reducethe weight loss of fresh produce through evaporation of water; humidifica-tion technology (misting) may be used on fresh produce during retail display.This method raises the moisture content of the air in a refrigerated opencabinet to the optimum level and lowers the vapor pressure differencebetween water at the surface of produce and in the air, resulting in a lowerrate of dehydration. A washing effect can also occur during humidifica-tion.32,37 However, it has been reported that a mist machine used to spraywater aerosol over produce bins was believed to be the cause of an outbreakof Legionnaire’s disease in Louisiana, an infection caused by the bacteriumLegionella pneumophilia. Water in the reservoir of a mist machine was con-taminated with this pathogenic bacterium. The illness develops when peopleinhale small droplets that contain this bacterium. The FDA recommendedthat cleaning and maintenance of mist machines should be performedweekly in order to ensure the safety of consumers and reduce the possibilityof a foodborne outbreak.38,39

8.4.4 The role of consumers in ensuring safety

Most fresh berries such as strawberries and raspberries are not washedduring the entire production process, including harvesting, packing, andtransportation. They are also regularly consumed fresh without further pro-cessing.29,40 Recognizing this has led to the recommendation of the mostappropriate and practical method for reducing naturally occurring microor-ganisms on fresh berries in the home. Washing with cold running tap wateris recommended for reducing indigenous microflora on fresh produce beforeeating or preparation.41 Washing lettuce and broccoli with tap water canreduce the natural microflora by 92.4% and 1 log10 colony-forming units(CFU)/g, respectively,32,42 while dipping strawberries in water reduces thepopulation of E. coli O157:H7 only 0.8 log10 units.40 Besides water, dilutedvinegar, chlorine solution, and commercial cleaning solutions specified forfresh fruits and vegetables are also used for washing fresh produce.43

Consumers usually believe that the incidence of foodborne illness is lessfrequently due to mishandling in the home. This misconception can lead to



inappropriate and unsafe food handling practices at the consumer level.43,44

Bryan45 reported that the improper handling and treatment of foods in thehome was the dominant factor leading to reported foodborne outbreaks inthe United States between 1961 and 1982. Potential sources of pathogenicmicroorganisms in fresh produce can be cross contamination from hands,food preparation surfaces, kitchen cutting boards, and knives during foodpreparation in the kitchen.46–48 Transmission of foodborne pathogens suchas Campylobacter jejuni and Salmonella sp. has occurred because of inadequatecleaning of kitchen cutting boards after use in preparing raw meat.49,50

According to Zhao et al.,47 large populations of Enterobacter aerogenes weretransferred to fresh produce cut on the same cutting board as contaminatedmeat. Moreover, these bacteria survived on the board for at least 4 hours.Ak et al.46 suggest that an effective method for disinfecting a contaminatedcutting board is to rinse it with hot water and a detergent. Microwaveirradiation was successful in eliminating bacteria from the surface and theinterior of wooden cutting boards, whereas its lethal effect on bacteria onthe surfaces of plastic cutting boards was limited.51

The best approach to reduce the problem of foodborne illness resultingfrom improper food handling practices at the consumer level is to engagein educational campaigns aimed at providing practical information aboutthe appropriate way to handle fresh produce prior to consumption. Theseeducational materials should be simple to read and easy to follow. Theyshould be accessed conveniently from multiple sources, such as supermarketbrochures, magazines and newspapers, produce containers, television pro-grams, websites, and refrigerator magnets.43

8.5 Intervention technologies for ensuring microbial safety of berries

Intervention technologies for inactivating or eliminating pathogens in foodcan utilize many well-recognized approaches, including heat preservation,chemical preservation using acidulants, antimicrobials, modified and con-trolled atmosphere storage or packaging, food irradiation, high hydrostaticpressure, etc. However, it is complex and a challenge for fresh produce, assome of the intervention technologies mentioned above will damage or killliving plant cells, leading to the loss of produce “freshness.” This sectionfocuses on specific intervention methods that can be integrated into a safe foodproduction and processing system to control pathogens and ensure microbi-ological safety of fresh fruits, including berries. These include temperaturecontrol, use of surface disinfectants, low-dose irradiation, and biocontrol.

Each method has distinct advantages and disadvantages dependingupon the type of fruit, mitigation protocol, and other variables. As discussedin previous sections, the best method for eliminating pathogens from freshfruits is to prevent contamination in the first place. However, this is notalways possible and the need to wash and sanitize many types of produce



remains of paramount importance to prevent disease outbreaks. It is impor-tant to point out that washing and sanitizing are unlikely to totally eliminateall pathogens after the produce is contaminated. Some berries cannot bewashed because of their delicate structure and problems with mold prolif-eration, and thus are often packaged in the field with minimal postharvesthandling or washing.

The efficacy of the method used to reduce microbial populations usuallydepends upon the type of treatment, the type and physiology of the targetmicroorganisms, characteristics of the produce surface (cracks, crevices,hydrophobic tendency, and texture), exposure time and concentration of thecleaner/sanitizer, pH, and temperature. The concentration/level of sani-tizers or other intervention methods may be limited by unacceptable sensoryimpact on the produce. Infiltration of microorganisms into points below thesurface of produce is problematic. While it is known that microorganismscan enter produce under certain handling conditions, the significance of anysuch contamination to public health requires further study.

8.5.1 Temperature control

While refrigeration is critical for the quality and shelf life of fruits, it cannotbe relied on to prevent the growth of pathogenic microorganisms on pro-duce. Populations of L. monocytogenes remained constant or grew on avariety of whole and cut produce stored at refrigeration temperatures.52

Under certain chilled storage conditions, spoilage of the product by thenative microflora might not occur until after pathogen populations reachlevels capable of causing disease. While the growth of some pathogensmay be inhibited by refrigeration temperatures, survival can be enhancedunder certain conditions. For example, salmonellae and E. coli O157:H7survive for a longer period of time in fruit juices under refrigeration thanat room temperature.4,53

8.5.2 Surface disinfectants

The simple practice of washing raw fruits in hot water or water containingdetergent removes a portion of the pathogenic and spoilage microorganismsthat may be present, but studies showing the efficacy of these treatments arefew. Even washing fruits in potable water, then washing again or rinsing inpotable water aids in removing microorganisms. Additional 10-fold to100-fold reductions can sometimes be achieved by treatment with disinfec-tants. The resistance of microorganisms to disinfectants varies greatly withthe type and pH of the disinfectant, contact time, temperature, and thechemical and physical properties of the fruit surface. Each type of disinfec-tant has its own efficacy in killing microbial cells. Effectiveness depends onthe nature of the cells, as well as the characteristics of the fruit tissues andjuices. Some types of disinfectants are appropriate for use in direct contactwashes, while others are suitable only for equipment and containers used



to process, store, or transport fruits. The mechanism of action of manydisinfectants on microbial cells and the influence of factors associated withplant materials are poorly understood. The legal use of various treatmentsalso differs from country to country.

The most commonly studied and used surface disinfectants for wholeand fresh-cut fruits include chlorine, chlorine dioxide, bromine, iodine,quaternary ammonium compounds, acidic compounds with or without fattyacid surfactants, alkaline compounds, hydrogen peroxide, and ozone. Theirapplication depends on the type and nature of the fruits, application tem-perature, dosage, etc. Rodgers et al.54 compared different chemical sanitizersfor inactivating E. coli O157:H7 and L. monocytogenes on strawberries. Ozone(3 ppm), chlorine dioxide (3 and 5 ppm), chlorinated trisodium phosphate(100 and 200 ppm chlorine), and peroxyacetic acid (80 ppm) were assessedfor the reduction of these two pathogens inoculated on fresh strawberries ata level of 106. Ozone and chlorine dioxide (5 ppm) were the most effectivetreatments, reducing populations about 5.6 log, with chlorine dioxide (3 ppm)and chlorinated trisodium phosphate (200 ppm chlorine) resulting in maxi-mum reductions of about 4.9 log. Peroxyacetic acid was the least effectivesanitizer (about 4.4 log reduction). During storage at 4°C for 9 days aftertreatment, populations of both pathogens remained relatively unchanged.The functionality, examples of application, and conditions in the use ofsurface disinfectants in fruit and vegetable sanitation have been discussedin great detail by Beuchat55 and Heard.56

8.5.3 Low-dose irradiation

Ionizing radiation from 60Co, 137Cs, or machine-generated electron beams,alone or in combination with other treatments such as hot water, may beused as a means of extending the shelf life of fresh produce.57 The lethalityof irradiation is determined by the targeted microorganisms (types of bac-teria, molds, or yeast), the condition of the treated item, and environmentalfactors. Low-dose treatments (less than 1 kGy) inhibit sprouting of tubers,bulbs, and roots, delay produce maturation, eliminate insects in grains, fruits,and nuts, and kill parasites in meats. Medium-dose treatments (1 to 10 kGy)reduce microbial populations, including pathogens, on or in foods. However,produce treated with doses greater than 1 kGy cannot use the term “fresh”(21 CFR 101.95).

Several studies have investigated the use of irradiation in combinationwith other treatments on prolonging the postharvest life of fresh strawber-ries. For example, O’Connor and Mitchell58 analyzed 17 samples of straw-berries from seven different growers for total counts, Enterobacteriaceae,fluorescent pseudomonads, and yeast and mold counts before and afterirradiation at 1.2 or 2 kGy. Enterobacteriaceae were absent (less than 5 CFU/g)from all irradiated strawberries (fresh and stored for 5 days at 8°C), but werealways detected at counts of greater than 30 CFU/g in untreated samples.Ouattara et al.59 determined the effectiveness of low-dose irradiation (0 and



3 kGy) combined with protein-based edible coatings on extending the shelflife of fresh strawberries. Results showed that coating with irradiated proteinsolutions resulted in significant reductions in the percentage of mold contam-ination. Pan et al.60 investigated the effects of ultraviolet C (UV-C) (4.1 kJ/m2)and heat treatment (45°C, 3 hours in air) either separately or combined onfruit quality and the development of surface fungal infections in in vitrogermination assays on conidia of B. cinerea and Rhizopus stolonifer. The com-bined treatment reduced fungal infections and delayed in vitro germinationof B. cinerea conidia. It was concluded that the combination of UV-C andheat treatment enhanced the benefits of applying each treatment separatelyand could be useful for improving and extending the postharvest life ofstrawberries.

8.5.4 Biocontrol

The application of biocontrol concepts may be useful for creating additionalmicrobial hurdles in fruits, especially fresh-cut fruits, to enhance productsafety. Biocontrol methods include the use of56

• Antagonistic organisms to control the growth of either spoilage orpathogenic species, most often called biopreservation.

• Natural antimicrobial compounds to control microbial growth.• Natural plant defenses to reduce microbial attack-induced resistance.

There are few published reports on the use of biocontrol agents to pre-vent the growth of human pathogens on fruits. Janisiewicz et al.61 reportedthat Pseudomonas syringiae prevented the growth of E. coli O157:H7 inwounds of apples. Populations of the pathogen increased 2 log in woundsthat were not treated with the antagonist, but they did not increase inwounds treated with P. syringiae. The application of microorganisms to pre-vent the proliferation of postharvest spoilage organisms has been studiedextensively.62–66 Studies suggest that nonpathogenic microorganisms appliedto produce surfaces might outcompete pathogens for physical space andnutrients and may produce antagonistic compounds that negatively affectthe viability of pathogens. Additional research on biocontrol of humanpathogens on produce is warranted to fully evaluate this approach as beingpractical and efficacious.

Microorganisms such as lactic acid bacteria are used as biopreservativeagents in foods to inhibit the growth of other undesirable species.56 Mecha-nisms of antagonism include competition for nutrients, binding of nutrients,and production of metabolic products with antimicrobial activity. Fermenta-tion with lactic acid bacteria is a traditional biopreservation method employedto increase the safety and quality of foods, including fruit. In recent years,lactic acid bacteria have been used as competitive biocontrol agents and antag-onists in nonfermented foods.67 These organisms are often present on thesurface of fruits and vegetables and, if encouraged, may reduce the growth of



other indigenous spoilage organisms or foodborne pathogens. Lactic acidbacteria are known to produce antimicrobial metabolites, such as lactic andacetic acid, hydrogen peroxide, and enzymes including lactoperoxidase.

The use of natural antimicrobials from plants and their possible appli-cation in minimally processed fruits and vegetables was reviewed byLopez-Malo.68 Plants, herbs, and spices, as well as their derived essential oilsand isolated compounds contain a large number of substances that are knownto inhibit various metabolic activities of bacteria, yeast, and molds, althoughmany of them are yet incompletely exploited. Major components withantimicrobial activity found in these resources are phenolic compounds,terpenes, aliphatic alcohol, aldehydes, ketones, acids, and isoflavonoids.Their effectiveness in inhibiting spoilage and pathogenic microorganismsdepends on many factors, including the composition of the food (pH, wateractivity, presence of other inhibitors, interaction with the food matrix, etc.),initial contamination level, handling and distribution (length, temperature,and packaging in storage), and possible synergistic or additive interactioneffects with other antimicrobial factors. The application of natural antimi-crobials in fruits requires a better understanding of the modes of action andtheir interactions with other preservation factors, as well as knowledge ofthe interactions between the stress factors applied and the fruit matrix.

Several studies have demonstrated that berry phenolic compoundsinhibit the growth of human pathogens such as Salmonella, Staphylococcus,and E. coli O157:H7. Utilization of the antimicrobial activity of berry phenoliccompounds as stand-alone natural antimicrobial agents or in concert withother antimicrobial systems may offer many new applications for the pro-duce industry.

The concept of “induced resistance” in plants to microorganisms thatcause pathologies in plant systems has also attracted attention.69 In recentyears, researchers have begun to focus efforts on the mechanisms and sig-naling pathways plants use to resist disease. In addition, biotechnologycompanies are engineering plants to resist pests. While speculative, it isconceivable that research on biocontrol efforts through induced resistanceor genetic engineering could lead to plants that resist human pathogens inaddition to plant pathogens.

8.6 ConclusionFresh berries are an important component of our diet and as such must beprovided to the consumer free of any contaminating pathogenic microorgan-isms. The historical record of berry safety clearly indicates that berry fruit isnot significant source of microorganisms that cause foodborne illness. How-ever, that is not to say that we in the berry industry can afford to be lax ortake shortcuts that may compromise safety. Food safety is a complex dynamicinterplay between very adaptable and opportunistic microorganisms, an everevolving and changing agricultural production landscape, and a humanpopulation whose food choices demand fresher and less processed products.



In this chapter we examined the potential food safety concerns that mayexist with berry fruits and the ecological, environmental, and production prac-tices that may be important in pathogen contamination. The inherent acidiccomposition of berries is likely a primary barrier to long-term pathogensurvival and growth. However, transient contamination of berries with patho-gens can present a potential food safety threat. Therefore it is prudent thatproducers, transporters, and retailers of fresh berry fruits provide the samesafety oversight and procedures as would be required for potentially morehazardous produce such as leafy vegetables and melons. Good agriculturalpractices are the cornerstone of ensuring the safety of fresh berries; however,it does not end there. In our discussion, we have stressed that ensuring safetyis the responsibility of all parties involved in the production, transportation,handling, display, and sale of berries and berry products. The consumingpublic also has a responsibility and should be involved in practicing safeprocedures when storing, handling, and serving food. Keep it safe!

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43. Li-Cohen, A.E. and Bruhn, C.M., Safety of consumer handling of fresh pro-duce from the time of purchase to the plate: a comprehensive consumersurvey, J. Food Prot., 65, 1287, 2002.

44. Healthy marketplace: working towards ensuring the supply of safer food,WHO-EM/FCS/005/E/G/11.03/1000, World Health Organization, Cairo,2003.

45. Bryan, F.L., Risks of practices, procedures and processes that lead to outbreaksof foodborne diseases, J. Food Prot., 51, 663, 1988.

46 Ak, N.O., Cliver, D.O., and Kaspar, C.W., Decontamination of plastic andwooden cutting boards for kitchen use, J. Food Prot., 57, 23, 1994.

47. Zhao, P., Zhoa, T., Doyle, M.P., Rubino, J.R., and Meng, J., Development of amodel for evaluation of microbial cross-contamination in the kitchen, J. FoodProt., 61, 960, 1998.



48. Venkitanarayanan, K.S., Ezeike, G.O., Hung, Y.C., and Doyle, M.P., Inactiva-tion of Escherichia coli O157:H7 and Listeria monocytogenes on plastic kitchencutting boards by electrolyzed oxidizing water, J. Food Prot., 62, 857, 1999.

49. Boer, E.D. and Hahne, M., Cross-contamination with Campylobacter jejuni andSalmonella spp. from raw chicken products during food preparation, J. FoodProt., 53, 1067, 1990.

50. Klontz, K.C., Timbo, B., Fein, S., and Levy, A., Prevalence of selected foodconsumption and preparation behaviors associated with increased risks offood-borne disease, J. Food Prot., 58, 927, 1995.

51. Park, P.K. and Cliver, D.O., Disinfection of household cutting boards withmicrowave oven, J. Food Prot., 59, 1049, 1996.

52. Farber, J.M., Wang, S.L., Cai, Y., and Zhang, S., Changes in populations ofListeria monocytogenes inoculated on packaged fresh-cut vegetables, J FoodProt., 61, 192, 1998.

53. Zhao, T., Doyle, M.P., and Besser, R.E., Fate of enterohemorrhagic Escherichiacoli O157:H7 in apple cider with and without preservatives, Appl. Environ.Microbiol., 59, 2526, 1993.

54. Rodgers, S.L., Cash, J.N., Siddiq, M., and Ryser, E.T., A comparison of differentchemical sanitizers for inactivating Escherichia coli O157:H7 and Listeria mono-cytogenes in solution and on apples, lettuce, strawberries, and cantaloupe,J. Food Prot., 67, 721, 2004.

55. Beuchat, L.P., Use of sanitizers in raw fruit and vegetable processing, inMinimally Processed Fruits and Vegetables. Fundamental Aspects and Applications,Alzamora, S.M., Tapia, M.L., and Lopex-Malo, A., Eds., Aspen, Gaithersburg,MD, 2000, p. 63.

56. Heard, G.M., Microbiology of fresh-cut produce, in Fresh-Cut Fruits andVegetables: Science, Technology, and Market, Lamikanra, O., Ed., CRC Press,New York, 2002, p. 187.

57. Thayer, D.W., Josephson, E.S., Brynjolfsson, A., and Giddings, G.G., Radiationpasteurization of food, Issue Paper No. 7, Council for Agricultural Scienceand Technology, Ames, IA, 1996, p. 1.

58. O’Connor, R.E. and Mitchell, G.E., Effect of irradiation on microorganisms instrawberries, Int. J. Food Microbiol., 12, 247, 1991.

59. Ouattaraa, B., Sabatoc, S.F., and Lacroix, M., Use of gamma-irradiation tech-nology in combination with edible coating to produce shelf-stable foods,Radiat. Phys. Chem., 63, 305, 2002.

60. Pan, J., Vicente, A.R., Mart’nez, G.A., Chaves, A.R., and Civello, P.M., Com-bined use of UV-C irradiation and heat treatment to improve postharvest lifeof strawberry fruit, J. Sci. Food Agric., 84, 1831, 2004.

61. Janisiewicz, W.J., Conway, W.S., and Leverentz, B., Biological control of post-harvest decays of apple can prevent growth of Escherichia coli O157:H7 inapple wounds, J Food Prot., 62, 1372, 1999.

62. Smilanick, J.L. and Denis-Arrue, R., Control of green mold of lemons withPseudomonas species, Plant Dis., 76, 481, 1992.

63. Janisiewicz, W.J. and Bors, B., Development of a microbial community ofbacterial and yeast antagonists to control wound-invading postharvest patho-gens of fruit, Appl. Environ. Microbiol., 61, 3261, 1995.

64. Leibinger, W., Breuker, B., Hahn, M., and Mendgen, K., Control of postharvestpathogens and colonization of the apple surface by antagonistic microorgan-isms in the field, Phytopathology, 87, 1103, 1997.



65. El-Ghaouth, A., Smilanick, J.L., Brown, G.E., Ippolito, A., Wisniewski, M., andWilson, C.L., Application of Candida saitoana and glycochitosan for the controlof postharvest diseases of apple and citrus fruit under semi-commercial con-ditions, Plant Dis., 84, 243, 2000.

66. Usall, J., Teixido, N., Fons, E., and Vinas, I., Biological control of blue mouldon apple by a strain of Candida sake under several controlled atmosphereconditions, Int. J. Food Microbiol., 58, 83, 2000.

67. Breidt, F. and Fleming, H.P., Using lactic acid bacteria to improve the safetyof minimally processed fruits and vegetables, Food Technol., 51, 44, 1997.

68. Lopez-Malo, A., Alzamora, S.M., and Guerrero, S., Natural antimicrobial fromplants, in Minimally Processed Fruits and Vegetables. Fundamental Aspects andApplications, Alzamora, S.M., Tapia, M.L., and Lopex-Malo, A., Eds., Aspen,Gaithersburg, MD, 2000, p. 237.

69. Hammerschmidt, R., Induced disease resistance: how do induced plants stoppathogens, Physiol. Mol. Plant Pathol., 55, 77, 1999.

70. Health Canada, Qualitative risk assessment: unpasteurized fruit juice/cider,in Health Risk Assessment, Food Directorate, Health Products and Food Branch,Ottawa, Ontario, Canada, 2000.

71. Nagy S., Chen, C.S., and Shaw, P.E., Fruit Juice Processing Technology, Agscience,Auburndale, FL, 1993.



261

chapter 9

Postharvest handling, storage, and treatment of fresh market berries

Cynthia Bower

Contents

9.1 Introduction ............................................................................................... 2629.1.1 From field to market ...................................................................2629.1.2 The importance of shelf life extension ..................................... 264

9.2 Decay and disease control....................................................................... 2659.2.1 Postharvest diseases in berries .................................................. 2659.2.2 Chemical control of postharvest decay .................................... 2689.2.3 Sanitation ....................................................................................... 269

9.3 Cold storage for extending shelf life ..................................................... 2699.3.1 Postharvest cooling requirements ............................................. 2709.3.2 Additional methods for quality retention................................ 271

9.4 Controlled atmosphere for storage and packaging ............................ 2739.4.1 Controlled atmosphere storage.................................................. 2739.4.2 Modified atmosphere packaging............................................... 2769.4.3 Effects of CA and MAP............................................................... 278

9.5 Edible coatings for extending the shelf life of berries........................ 2789.5.1 Developing coatings and films .................................................. 2799.5.2 Incorporating antimicrobial agents ........................................... 2799.5.3 Other novel coatings.................................................................... 280

9.6 Other technologies or treatments for shelf life extension.................. 2809.6.1 Irradiation...................................................................................... 2819.6.2 Biocontrol agents .......................................................................... 281

5802_C009.fm Page 261 Wednesday, March 21, 2007 12:48 PM


9.6.3 Other treatments........................................................................... 2819.7 Conclusion.................................................................................................. 282References ........................................................................................................... 284

9.1 Introduction

A perfect berry growing in the field may not reach the consumer in the sameflawless condition. Producing high-quality berry fruit is only the first step.Delivering them to market in premium condition is also essential to com-mand the buyer’s attention. The handling of berries during harvesting, sort-ing, packing, storage, and transport determines whether the crop will besuitable for fresh market sales. Postharvest handling and storage techniqueshave been designed to maintain the maximum quality, prolong shelf life,and retain consumer appeal so that the grower will receive the highestmarket price at the time of sale. The goal of this chapter is to provideinformation on quality retention in fresh berry fruits through proper post-harvest handling and storage.

9.1.1 From field to market

Production of consistently high-quality berries must be combined with care-ful harvesting, immediate cooling, appropriate packaging, rapid transport,and effective marketing to compete in the fresh market sector. This beginswith finding and training the seasonal labor needed to harvest, sort, andpack the crop, since producing berry fruit for fresh market sales is very laborintensive. Mechanical harvesting is a less expensive method than employingmanual labor, but the savings are diminished if the harvested berries are notacceptable as a fresh market commodity. Berries harvested by machines canbe easily bruised, significantly decreasing their shelf life. For blueberries, thefirmness of those harvested by machine was decreased by 36% when com-pared to berries harvested by hand.

1

Mechanical harvesters cannot distin-guish between good and unacceptable quality fruit, necessitating extra post-harvest handling to separate berries from foreign matter and sort themaccording to quality. This additional step is time consuming, further decreas-ing the quality of the berries, resulting in a shorter shelf life, and a berrycrop that is less competitive in the fresh market and more suited for frozenor processed products. Although new prototypes show promise, mechanicalharvesting methods are currently not recommended for most cultivars ofberry intended for fresh market sales. Instead, experienced pickers shouldbe instructed to select only perfectly ripe berries for harvest. Visible defectssuch as broken skin, decay, mold, and insect damage should be manuallysorted out while picking to minimize handling, thereby increasing the shelflife of the crop. It is recommended that high-value fresh market berries beharvested directly into retail containers to further decrease the possibility ofbruising.

2

After harvesting, rapid cooling of the berries is required to removefield heat. Postharvest cooling slows the berry’s respiration and decreases


Chapter 9: Postharvest handling, storage, and treatment 263

the enzyme activity that leads to softening. Cooling also delays the growthof spoilage microorganisms (bacteria and mold), which cause decay andpremature loss of quality. Recommended temperatures for cooling and stor-age vary according to different chilling susceptibilities among berries. Forexample, strawberries must be quickly cooled to slow the decay of berriesat the center of the pallet, as they continue to produce heat from their naturalrespiration. However, blueberries do not benefit from immediate cooling dueto condensation that forms on the cooled berries when moved to ambienttemperatures for packaging.

3

Packaging is another important consideration for retaining postharvestquality and extending the shelf life of perishable fruit. The container mustenclose and protect the berries from mechanical damage, yet still be conve-nient for transport. Packaging can be made from a variety materials to fillspecific needs. Containers made from pulp absorb unwanted surface mois-ture, protecting the berries from water damage and extending their shelf life.Clamshell containers provide a more rigid packaging system that offersadded protection for high value products such as fresh berries. Cushionedpackaging materials may be required during harvest to prevent bruisingwhen berries are dropped from a height greater than 15 cm.

4

Air-freightedberries require a sturdier, better insulated package than berries destined forthe local market. Controlled atmosphere (CA) requirements (temperature,humidity, oxygen/carbon dioxide [O

2

/CO

2

] mix) also influence the packag-ing type. Vented packaging, allowing refrigerated air to circulate while theberries are being cooled, is essential when berries are harvested directly intotheir final containers. For example, strawberries, which are usually packagedin the field before precooling, used to be packaged in open-top pint baskets.They are now packaged in the more protective clamshell packaging withhinged lids.

5

There is a decrease in the vent area associated with the newcontainers; however, it is still sufficient to allow forced-air precooling beforethe berries are transferred into refrigerated storage. After cooling, a layer ofplastic wrap may be added to minimize moisture loss during storage.

Optimum storage conditions vary among different berries.

6,7

CA storageaccounts for these differences by adjusting the normal atmospheric compo-sition of air around the fruit to one that will slow the respiration rate.Generally O

2

levels are lowered and the amount of CO

2

is increased. Inaddition to extending the shelf life, proper storage conditions also slowenzyme degradation and retain concentrations of easily lost vitamins suchas ascorbic acid. Modified atmosphere packaging (MAP) may be employedto maintain the favorable environment within a sealed package until theproduct is sold. The modified atmosphere extends the shelf life of the berries,while the sealed container protects them from exposure to disease and otherenvironmental contaminants.

Rapid transport is also necessary for providing high-quality fresh marketberries. Bruising can occur in transit from the vibrations common duringnormal shipping procedures.

8

Poor-quality berries cannot be sold in the freshmarket, which results in a direct dollar loss to the grower. Ideally berry fruit



would be picked often so that harvesting would occur at the appropriateripeness for each berry. The crop would be handled carefully during sortingand packaging, and then cooled immediately to retain flavor and extendshelf life. The berries would be rapidly shipped under refrigeration for freshmarket sales (Figure 9.1). Berries for sale in retail outlets should be displayedunder refrigeration without mist to extend shelf life and inhibit the growthof mold. These conditions, together with effective marketing, will ensurethat the berries garner their maximum value.

9.1.2 The importance of shelf life extension

Fresh market berry fruit offers convenience, since little or no preparationtime is needed to add strawberries to short cake or stir blueberries intoyogurt. Consumers are also becoming more aware of the health benefitsassociated with fresh berries. Antioxidants, compounds that protect againstcancer-causing free radicals in our tissues, have been found in berry fruit.

9

Berries also contain phytochemicals that inhibit mutagenesis caused by car-cinogenic compounds.

10

Certain fresh berries have demonstrated antibacte-rial activity and may even enhance shelf life when added to foods.

11

How-ever, these health benefits diminish in the berries over time. For example,the folate concentration in strawberries decreased after 9 days when storedat 4

°

C.

12

This highlights the importance of proper handling and storageprotocols for fresh market berries to prolong shelf life, preserve maximumquality, and retain the health benefits of the fruit.

When considering berry quality, there is more to the evaluation processthan meets the eye. The purchase of fresh berries is generally based onperceived quality attributes such as freshness, plumpness, color, and overallappearance. A uniform blue color with a dusty appearance (“bloom”) ishighly desirable for blueberries; however, bloom can be easily lost throughexcessive handling. Because berries are so easily damaged between field andmarket, a strict regimen of proper postharvest handling is essential to main-tain the quality necessary for fresh market sales. Table 9.1 lists postharvesttechniques commonly used for preserving the quality of berry fruit.

Figure 9.1

Destination of berry fruit intended for fresh market sales.

U-Pick RoadsideStands

Harvest

Cool

Package

TransportMarketFarmer’s

StoresGrocery

SalesInterstateOverseas

Restaurants



9.2 Decay and disease control

Berries are a highly perishable commodity by design. They are the repro-ductive component of the plant, consisting of soft, edible tissue specificallydesigned to attract animals to assist in the dispersal of seeds. Unfortu-nately the evolutionary characteristics, which are so valuable for theplants, make it difficult for humans to prolong the storage time of freshmarket berries.

9.2.1 Postharvest diseases in berries

Berries are subject to postharvest losses from a variety of sources. Physicalinjuries, such as bruising and abrasions, may occur during handling as warmberries are transported from the field. When damage results in leakage ofjuice, the berries become more susceptible to postharvest decay, renderingthem unsuitable for fresh market sales.

E

gg-laying insects, attracted to thewarm berry juices, may also transfer contaminants from infected to healthyfruit. Even the environment may expose berries to disease organisms throughfarm equipment, pallets, and other difficult-to-sanitize items

.

Once the

Table 9.1

Factors Affecting Postharvest Quality of Fresh Market Berry Fruit

Postharvest techniques

Method for preserving quality Rationale

Harvesting Pick directly into retail containers

Store berries away from heat and sunlight

To reduce handling of berriesTo prevent additional heating

Cooling Cool berries immediately (generally using a forced-air system)

To remove field heat

Refrigerated storage

Store in a cold room (equipped with refrigeration unit)

To slow ripening and decrease microbial growth

Controlled atmosphere storage

Decrease oxygen levels during storage and increase concentration of carbon dioxide

To reduce the respiration rate of the berries and slow the ripening process

Packaging Use rigid containersProvide a plastic overwrap

To protect berries from damageTo resist environmental

contaminants

Modified atmosphere packaging

Seal packaged berries in an environment favorable to decreased ripening

To extend shelf life and protect the berries from external contaminants

Transport to market

Hire refrigerated trucks To decrease respiration of berries and inhibit the growth of mold



berries have been damaged, regardless of the initial cause, the exposed tissuebecomes vulnerable to secondary invasions by common saprophytes.

Diseases are the greatest cause of postharvest losses in berries. Thehigh humidity in cold storage, which is necessary to preserve freshness,can actually promote microbial spoilage unless there is adequate air flowto prevent moisture condensation on the berry surface. Fungi thrive on thecarbohydrate substrate provided by fruit juice and are much more preva-lent than bacterial or viral spoilage organisms on postharvest berries. Com-mon pathogens of berry fruits are listed in Table 9.2. Removal of visiblydecayed berries can sometimes prevent the spread of diseases to healthyberries (nesting). However, fungal diseases are difficult to control sincesome, such as

Rhizopus

sp., have spores that can be easily spread throughthe air, and others, such as

Botrytis cinerea

, can grow at refrigerated tem-peratures. Storage and shipment under CA conditions may be required tosuppress the growth of fungal contaminants on berries if immediate saleis not possible.

Botrytis cinerea

(gray mold) is an important cause of decay in berryfruit. However, controlling it is not as easy as simply reducing thenumber of contaminating fungal spores. The incidence of

B. cinerea

infection on fresh grapes after prolonged cold storage was not influencedby conidial density on the grape surfaces, but by the resistance level ofthe host.

13

Initial infection can occur during postharvest handling oreven earlier, while the fruit is still maturing in the field. Fungal sporesare able to survive in a dormant state within the berry until the sugarconcentration is sufficient to support their growth. Postharvest handlingcan spread the fungus, which may continue to grow even at cold storagetemperatures.

Not all infected berries show evidence of disease. Bacterial pathogenscan contaminate berries, leading to serious illness in humans.

Listeria

mono-cytogenes

,

Salmonella

sp., and

Escherichia coli

O157:H7 were each capable ofsurvival, but not growth, on the surfaces of fresh strawberries.

2,14

Viral out-breaks, such as hepatitis, have been transmitted through berries by workersduring handling.

15

Protozoan parasites are also a concern. A cyclosporiasisoutbreak in 1996 was associated with fresh raspberries imported from Gua-temala;

16

another outbreak occurred in 1997.

17

Many bacteria, viruses, andprotozoa can survive on fruit long enough to infect consumers. Since freshmarket berries are generally not washed before sale, there is no chance forthe producer to disinfect them, leaving the ultimate responsibility for foodsafety in the hands of the consumer.

Berries can also be infested with insect pests and spiders. These poselittle damage to stored fruits, but may require treatment before export. Forexample, blueberry maggots (

Rhagoletis mendax

) can create quarantine issuesduring shipment, as can the discovery of black widow spiders. Methyl bro-mide and sulfur dioxide (SO

2

) are both effective against insect pests such asmealybugs;

18

however, the U.S. Environmental Protection Agency (EPA) willlimit the use of methyl bromide starting in 2006.



Tabl

e 9.

2

Com

mon

Fun

gal D

isea

ses

of B

erry

Fru

it D

urin

g Po

stha

rves

t St

orag

e

Dis

ease

Cau

sati

ve a

gen

tR

emar

ksR

efer

ence

s

Gra

y m

old

Bot

ryti

s ci

nere

a

Impo

rtan

t ca

use

of f

ruit

rot

on

stra

wbe

rrie

s,

blac

kber

ries

, blu

eber

ries

, ras

pber

ries

, and

gra

pes

70, 7

1

Rhi

zopu

s

rot

Rhi

zopu

s st

olon

ifer

Com

mon

pos

thar

vest

rot

in o

verr

ipe

berr

ies,

but

ca

nnot

gro

w b

elow

5

°

C70

, 71

Ant

hrac

nose

fru

it r

ot

(bla

ck s

pot)

Col

leto

tric

hum

acu

tatu

m

an

d

Col

leto

tric

hum

gl

oeso

spor

iode

s

Impo

rtan

t ca

use

of f

ruit

rot

on

stra

wbe

rrie

s,

blue

berr

ies,

cra

nber

ries

, and

gra

pes

72

Bot

ryos

phae

ria

fru

it r

ot

Bot

ryos

phae

ria

doth

idea

Prin

cipa

l sto

rage

rot

of

cran

berr

ies;

can

als

o af

fect

gr

apes

73, 7

4

Blu

e m

old

Pen

icill

ium

sp.

Aff

ects

gra

pes

75

Lea

ther

rot

Phy

toph

thor

a ca

ctor

um

Occ

asio

nally

occ

urs

on s

traw

berr

ies

76

Cla

dosp

oriu

m

rot

Cla

dosp

oriu

m

sp.

Occ

asio

nally

occ

urs

on b

erri

es a

nd g

rape

s77

Fusa

rium

rot

Fusa

rium

sp.

Occ

asio

nally

occ

urs

on b

erri

es a

nd g

rape

s77

Alt

erna

ria

rot

Alt

erna

ria

sp.

Occ

asio

nally

occ

urs

on b

erri

es a

nd g

rape

s77

Lea

k

Muc

or

sp.

Occ

asio

nally

occ

urs

on b

erri

es a

nd g

rape

s78



9.2.2 Chemical control of postharvest decay

Latent damage (injuries that occur at one point during postharvest handling,but don’t appear until later) can also increase the risk of contamination. If aberry experiences rough handling during harvest, signs of bruising may notbe visible immediately; however, increased susceptibility to infection mayoccur, leading to a lower quality fruit that may eventually be discarded. Latentdamage also arises from quiescent infections, which were acquired in the field,but were inhibited by the host’s natural defenses until after harvest. Sinceberries that suffer tissue injuries require the same cost inputs as undamagedberries for packing, cooling, transporting, and marketing, it is economicallybeneficial to find and remove damaged fruit as early in the process as possible.

Postharvest chemical treatments are generally not necessary for freshmarket berry fruits. Careful harvesting, followed by prompt cooling andrapid sale should be sufficient to control most diseases. When chemicalagents are needed to control decay, the choice of treatment can be guidedby the susceptibility of the infecting organism, its depth of penetration intothe host tissue, and the characteristics of the compound being applied. Some-times pathogens are resistant to chemical treatments except at very highdoses or the infecting organisms are inaccessible within the berry. Chemicalagents, when applied after harvest, must be at a safe dose so as to leave notoxic residues on the berries.

To control decay organisms during long-term storage (such as grapes beingprepared for export), fumigation with SO

2

has proven effective in blocking thecellular metabolism of microorganisms. Postharvest decay of table grapesinfected by

Penicillium expansum

and

B. cinerea

can be reduced by SO

2

-generatingpads during long-term cold storage.

19

Table grapes in gas-tight containers canbe fumigated by slow-release SO

2

-generating pads without noticeably injuringthe fruit.

20

There are two common varieties of SO

2

-generating units for storageand transportation of grapes. The first is a slow-release method designed forgrapes that have received a preliminary fumigation with SO

2

. The second“two-stage” method involves an initial rapid release of SO

2

, followed by a slowerrelease to maintain an effective concentration of the fumigant. The SO

2

gas canbe retained by using plastic liners within the shipping containers to controlpostharvest decay for at least 1 month. The amount of SO

2

required for long-termcontrol (6 weeks, 0

°

C) of

B. cinerea

on grapes was found to be more than5.5 µmol/kg-hr (3.00

µ

l/l inlet concentration), although nesting was effectivelycontrolled at concentrations of 3.6 µmol/kg-hr.

20

Grapes should receive regular fumigation during transport to suppressthe growth of

B. cinerea

; however, exposure to SO

2

can injure some culti-vars.

21,22

Injuries associated with the use of SO

2

include bleaching and accu-mulation of sulfite residues. Damaged berries accumulated up to seven timesmore sulfite residue than their undamaged counterparts.

23

Careful handlingof grape clusters is also required because SO

2

can cause berries to loosenfrom their pedicels. To minimize the amount of SO

2

required for fumigation,only sound berries that are free from decay should be treated.



Other chemical methods to control postharvest decay of berry fruit havebeen evaluated. Fumigation with acetic acid controlled decay of table grapes aswell as SO

2

for 6 weeks at 5

°

C, with no significant differences in

°

Brix, titratableacidity, pH, and color of the fruit.

24

Fungal pathogens of strawberry fruits werecontrolled using a dimethoxybenzoic acid dip to inhibit

in vitro

spore germina-tion and mycelial growth of

B. cinerea

and

Rhizopus stolonifer

.

25

Exposure to asolution of 30% ethanol (24

°

C) completely inhibited the germination of

B. cinerea

spores in freshly harvested table grapes and reduced decay by 50% after 35 daysof storage at 1

°

C.

26

Chlorination has been used as a preventive rinse for blue-berries; however, it removes the bloom and bleaches the fruit, making the berriesunacceptable for fresh market sales. Exposure to ozone gas (0.3 ppm) success-fully controlled

B. cinerea

on grapes stored for 7 weeks at 5

°

C; however, ozonewas significantly less effective when sprayed onto the fruit.

27

In addition, atsporicidal concentrations, ozone gas is toxic to humans.

9.2.3 Sanitation

Extending the shelf life of berries requires an effective method to inhibitmicrobial growth, together with a storage environment that is unfavorableto the progression of disease. Berries require high humidity during refriger-ated storage to maintain their shape and volume. Wet berries are moresusceptible to decay, necessitating rigorous sanitation practices in cold roomsto inhibit microbial growth. Damaged berries may leak juice, which can carrycontaminants from one surface to another. Decayed fruit are at risk whenthey come into contact with any type of contaminated equipment duringpacking and storage. Wooden baskets and bins are difficult to clean and maysupport fungal growth when wet. Berry handlers can also act as vectors tospread contamination.

Chlorine (sodium hypochlorite) solution is a common disinfectant forsanitizing food handling areas, although microorganisms sometimes dem-onstrate resistance. Ozone gas can also be used as a disinfectant whenapplied to surfaces that may come in contact with berries, as it inhibitssporulation of fungi and alters normal mycelial growth. Hydrogen peroxidecan also inhibit fungi associated with postharvest decay.

Keeping berries under constant refrigeration and maintaining cleanwork surfaces are two control measures recommended for inhibitingdecay-causing microorganisms that can lead to loss of marketable berries.Ultimately, adhering to good agricultural practices (GAPs) and having awell-designed hazard analysis critical control points (HACCP) plan are thebest strategies for protecting fresh berry fruit after harvest.

9.3 Cold storage for extending shelf life

Rapid postharvest cooling is the most important step for maintaining thequality of freshly picked berry fruit. Immediate refrigeration decreases therespiration rate of the berries and slows their ripening process. It reducestextural and color changes and slows the loss of flavor and salable weight.



Cooling also inhibits the growth of microorganisms that cause decay. Straw-berries held at 5

°

C developed more decay and had a shorter shelf life thanthose held at 0

°

C.

28

However, cooled air holds less water than the warm fieldair surrounding the berries at harvest, so humidity during refrigerated stor-age must be maintained to prevent moisture loss, which will cause the berriesto shrivel. Rapid cooling with proper humidity enhances the marketingpossibilities for growers by allowing a longer storage time of the crop before sale.

9.3.1 Postharvest cooling requirements

Refrigeration must be applied immediately after harvest to maximize theshelf life of perishable fruits such as berries. Precooling refers to the practiceof reducing the product’s temperature before subsequent operations such assorting and packaging are carried out at ambient temperatures. However,these temperature fluctuations can have a detrimental effect on berry quality.Although the term precooling is falling out of favor, the goal remains thesame: to provide continuous refrigeration from shortly after harvest untilthe consumer selects the product for purchase, without allowing the tem-perature of the berries to rise at any time in between.

Several refrigeration methods are available for reducing the temperatureof freshly picked berry fruit. Forced-air ventilation is most commonly usedto rapidly remove field heat. This technology consists of a refrigerated roomequipped with fans capable of pulling large volumes of cold air through andaround pallets filled with vented containers of produce. The use of forced-aircooling reduces berry deterioration, prolongs shelf life, and decreases theenergy-intensive interval required for cooling, resulting in more efficient useof farm resources. In addition to removing field heat, the cold moving airevaporates excess moisture from the surface of the berries, making them lesssusceptible to postharvest decay. Blueberries are often harvested duringhours when morning or evening dew is present. Removal of field moistureby forced-air ventilation retains the quality of the berries without causingweight loss or processing damage.

29

Another technology is “room cooling,” where the fruit is placed in arefrigerated space that does not contain a source of moving air. This methodis less effective than forced-air cooling for rapidly decreasing the temperatureof a perishable product since, in still air, berries cool slowly, with heat lostonly through conduction. This process is further slowed because the berriesare typically surrounded by insulators such as cellophane, paperboard, andair. Room cooling is an uneven and extremely slow method of refrigerationthat has proven unsatisfactory for perishable fruits such as berries. It isespecially inadequate for large containers or pallets, where the berries at thecenter continue to respire and produce heat long after the more exposedberries near the outside have cooled. A refrigerated room is more efficientlyused as a storage space for a previously cooled product, and when servingin that capacity, it requires only a small refrigeration unit. In addition toenergy savings, an advantage of moving cooled berries from a forced-air



environment to a refrigerated room is that less humidity control is required,since less moisture is lost through convection in the absence of moving air.

Rates for cooling a product depend on the temperature and velocity ofthe air flow during the initial refrigeration phase. When cooling berriesdirectly from the field, all containers should be positioned to allow maximumair circulation throughout the room. If forced-air cooling is used, the fansshould be shut off as soon as the desired temperature is reached to preventmoisture loss from the berries. The choice of cooling method and rate ofrefrigeration will depend on the characteristics of each variety of berry fruit.For example, blueberries are generally not refrigerated immediately afterharvest since severe condensation problems can occur when the temperatureis allowed to rise again during subsequent packing steps.

3

Many processes have been developed for cooling produce fresh fromthe field; however, not all methods are appropriate for berries. Crushed icehas been used to cover the top of harvested products (top icing), and icewater slurries have been injected into packages already stacked on pallets(liquid icing). However, icing is not recommended for cooling berry fruitbecause of the increased risk of freezing. Hydrocooling is also regarded asinappropriate for removing field heat from freshly harvested berries. Chilledwater flowing over fresh fruit removes heat 15 times faster than air at thesame temperature. However, most berries cannot tolerate wetting andbecome more susceptible to the growth of decay-causing organisms whenmoisture is present. Postharvest hydrocooling of strawberries was comparedwith conventional forced-air cooling to evaluate the subsequent risk of decayduring storage. No differences were found for short-term storage (7 days at1

°

C) unless berries were exposed to fungal spores in the water during hydro-cooling.

30

However, hydrocooling and evaporative cooling, a process whichmists the product under low humidity conditions, are technologies not gen-erally used to cool berries intended for fresh market sales.

9.3.2 Additional methods for quality retention

Berry fruit should be picked during the coolest part of the day, if possible,and should be held in a shaded area for the shortest time possible beforeapplying continuous refrigeration. During the initial cooling process, low-ering the temperature of the berry fruit is the primary goal; however, lossof moisture is also an important consideration. Humidity must be main-tained during storage to prevent the berries from losing moisture. Water lossdirectly translates into a lower salable weight and a reduced profit. The waterwithin a berry is in equilibrium with the water vapor in the air. If the relativehumidity is lower than 95%, moisture will move from inside the fruit to theoutside air. Grapes subjected to low moisture conditions may experiencedrying of their stems, causing individual berries to shatter loose from thecluster. Damaged berries are even more susceptible to shrinkage, since inju-ries to the skin increase the rate of water loss. Forced-air ventilation, whichis valuable for rapidly lowering the temperature of warm berries, can



accelerate the loss of moisture from cooling fruit unless adequate humidity issupplied. After cooling, a relative humidity of 95% can be maintained bywrapping the packaged berries with plastic film or packing them in containerswith plastic liners; however, corrugated boxes may weaken in the presence ofhigh humidity, allowing the berries to become bruised during transport.

Although high humidity is essential for stored berries, moisture pro-motes the growth of disease-causing organisms. This can be offset to somedegree by maintaining adequate air circulation and applying the coldeststorage temperatures allowable for each fruit without permitting freezing.Berries are mostly water, but they contain sugars and other soluble com-pounds that depress the freezing point below 0

°

C. The choice of coolingmethod and temperature of storage depend upon the type of berry fruitbeing cooled. For example, strawberries benefit from near-freezing temper-atures (0.6

°

C) that would damage a crop such as cranberries, which prefertemperatures closer to 4

°

C. Recommended storage conditions with estimatedpostharvest shelf lives are shown in Table 9.3.

Most berry fruit (such as blackberries, blueberries, raspberries, strawber-ries, and grapes) are not sensitive to chilling injuries, despite the near-freezingtemperatures recommended for cold storage. However, all berries can suffertissue damage after direct, prolonged contact with ice. The injuries may notbe visible for several days, but they can render the berry more susceptible todecay. Cranberries are sensitive to chilling injuries,

31

resulting in a dull appear-ance and rubbery texture. Warming the cold berries to 21

°

C for 1 day eachmonth was found to reduce the damage.

32

Transporting cooled berries in a refrigerated vehicle will also preservequality and extend shelf life for the fresh market. Although refrigeratedtrucks are not designed to cool warm berries loaded directly from the field,they can maintain the temperature of a previously cooled container. Loadingthe pallets to ensure maximum air circulation will also delay quality loss

Table 9.3

Recommended Cold Storage Conditions for Fresh Berry Fruit

Common name

Scientific name

Storage temperature (

°

C)Optimum

humidity (%)Postharvest shelf life

a

Blackberries and their hybrids

Rubus sp. 0.5 to 0 90–95 2–3 days

Blueberries Vaccinium sp. 0.5 to 0 90–95 2–3 weeks

Cranberries Vacciniummacrocarpon

2.0 to 4.0 90–95 2–4 months

Grapes Vitis sp. 0.5 to 0 85 2–6 weeks

Raspberries Rubus ideaus 0.5 to 0 90–95 5–7 days

Strawberries Fragaria × ananassa

0.5 to 0 90–95 5–7 days

a Storage time will vary depending on cultivars.Source: Adapted from Salunkhe and Desai.79



during transport of fresh berry fruit. Maintaining a humidified environmentmay be difficult; however, short transit times combined with plastic-linedcontainers can be effective in preventing excessive moisture loss.

9.4 Controlled atmosphere for storage and packagingSenescence of highly perishable foods, such as fresh berry fruit, results fromthe cellular metabolism of the food itself through the process of respiration.Berries, like all fresh produce, are still alive after harvest. They continue torespire by taking up O2 and releasing CO2 as a waste product. Generally, theshelf life of a fruit varies inversely with its respiration rate, allowing cultivarswith lower respiratory rates to be stored longer than those with higher rates.The goal of CA storage is to slow the rate of respiration by continuously adjust-ing the ratio of gases that blanket the fruit. MAP is a self-contained form of CA,designed to maintain a CA for produce during transportation and storage.

9.4.1 Controlled atmosphere storage

Controlled atmosphere technologies were developed to preserve the qualityof postharvest fruits and vegetables. Air normally contains about 21% O2

and 0.03% CO2. Since the shelf life of a fruit is inversely related to its rate ofrespiration, adjusting the levels of O2 and CO2 to a ratio that decreases thefruit’s respiration rate will slow the ripening process and extend the storagetime. Low O2 levels can be used to delay ripening by inhibiting enzymes inthe ethylene production pathway. High CO2 concentrations can also disruptenzyme systems, such as the lipoxygenase pathway, which is involved inthe formation of aroma volatile compounds. Maintaining optimal CA con-ditions is especially important for strawberries, blackberries, and raspberries,which all have high rates of respiration. Figure 9.2 compares the percentagesof gases found in air versus those that might be used for CA storage.

Controlled atmosphere storage also decreases the decay rate of freshfruit by inhibiting aerobic bacteria and fungi. Low O2 levels and high CO2

concentrations demonstrated fungistatic effects on molds and produced lesssoftening and a longer shelf life when used to store strawberries.33 The mostcommon gases used for CA storage are O2, CO2, and nitrogen (N2). In theproper proportions, these gases exert an inhibitory effect on many microor-ganisms. High CO2 levels interfere with normal cellular metabolism and caninhibit molds and aerobic gram-negative bacteria; however, facultative andanaerobic bacteria are resistant, as are most fermentative yeasts.34 Treatmentsinvolving high concentrations of CO2 did not cause permanent injury duringshort-term storage.35 Other gases (such as chlorine, ethylene, nitrous oxide,ozone, and sulfur dioxide) have been evaluated as antimicrobial agents foruse in CA systems, but safety, regulatory, and monetary issues have madethem less attractive for commercial use.

Postharvest control of insects is an important issue when berry fruit mustmeet quarantine requirements before export. Low O2 levels can be effective



in controlling postharvest insect infestations.36 Thrips (Frankliniella occiden-talis) were completely eradicated on strawberries stored in a low O2 (lessthan 1%) environment or with high levels of CO2 (50% to 90%) without anydamage to the berries.37 In addition to inhibiting microorganisms and insects,CAs with O2 levels less than 1% can also protect against infestations by birdsand rodents. However, the fruit must be able to withstand the stress of alow O2 environment for a sufficient length of time to completely controlpests. Mild stress from adjusting the O2/CO2 concentrations usually resultsin no decrease in fruit quality. However, severe stress decreases oxidativephosphorylation, which prevents glycolysis and allows undesirable com-pounds to be formed as pyruvate is directed through the anaerobic path-way.38 Low O2 (less than 1%) did not significantly affect the soluble solidscontent, pH, or titratable acidity of strawberries after 10 days of storage.However, when O2 levels were too low (0% to 0.25%), strong off-flavors weredetectable, corresponding with volatiles produced during the fermentationthat occurs under anaerobic conditions.36 Combining low O2 levels withrefrigerated storage reduces the stress on berry fruits stored under CA con-ditions. Generally the negative effects caused by low O2 levels are reversiblewhen more favorable conditions are restored. Although low O2 levels are

Figure 9.2 Normal percentage of atmospheric gases.

OtherGases

(apprx 1%)

CarbonDioxide0.035%

Oxygen21%

Nitrogen78%

An example of controlledatmosphere storage gases

CarbonDioxide

20%

Nitrogen78%

Oxygen2%



typically associated with preservative effects in fruit, CA storage using highO2 concentrations has also proven beneficial. Grapes preserved with 80% O2

(10°C, 95% relative humidity) were able to retain their quality for 60 days.39

Elevated CO2 concentrations (greater than 50%) resulted in less decayof strawberries stored at 5°C and shielded the fruit from chilling injuries.38

However, the resulting disturbance in the respiratory enzyme system led toincreased deterioration after 8 days of storage. CO2 levels greater than 20%caused discoloration, softening, and off-flavor of raspberries.40 The ethanoland acetaldehyde concentrations were even higher in strawberries when CO2

levels were greater than 50% compared to those stored in 20% CO2. Highconcentrations of CO2 (greater than 50%) decreased the reddish color ofstrawberries, causing their skins to acquire a blue-red cast, although low O2

levels (less than 1%) had no effect on skin color.28

Taste panels rated strawberries stored in high CO2 environments ashaving off-flavors; however, sequential storage with 50% CO2 followed bystorage in air for several days before retail sale can eliminate this problem.When correctly applied, CA conditions decrease the respiration rate anddelay ripening, thereby increasing the shelf life of some berry fruit by up to6 weeks. The benefits of using CA storage are listed in Figure 9.3. However,CA storage is not without disadvantages. The technology is expensive, allcontainers must be airtight, and the gas exchange process can be slow. Inaddition, MAP may render products more vulnerable to the growth of food-borne pathogens if temperature abuse occurs during transport and storage,raising the concern that L. monocytogenes, Yersinia enterocolitica, Clostridiumbotulinum, and other pathogens will be able to grow.

Systems designed for CA storage can maintain the correct environmentby pumping in N2 gas to reduce O2 levels to the desired level. Berries withinthe storage unit continue to respire, further depleting O2 and elevating CO2.The quantity of CO2 is carefully monitored and when it exceeds a preset level,it can be removed by circulating the storage gases through a scrubber. Ethylenegas can also be removed at this time, although it generally does not pose aproblem for berries. Humidity must be monitored and carefully regulated.

Introducing 1.5% O2 to rapidly establish low O2 conditions, followed byan optimum mix of O2 and CO2 has proven effective for extending the shelf

Figure 9.3 Benefits of controlled atmosphere storage for berry fruit.

• lowers respiration rate• regulates ethylene production• decreases sensitivity to ethylene gas

• inhibits microorganisms (bacteria, mold)• controls insects• kills birds and rodents

Decreases rate of ripening

Reduces postharvest chemicals

Increases marketability• allows fully ripe fruit to be harvested• reduces exposure to chilling temperatures• permits transport to distant markets• extends quality and safety of fruits



life of fresh fruits.38 No loss of quality was visible when strawberries weretreated with 0% O2 or up to 80% CO2 for 6 days. When O2 levels were toolow (less than 0.25%) or CO2 levels were too high (greater than 50%), strongoff-flavors were detectable, corresponding with volatiles (e.g., ethanol,acetaldehyde) produced during the fermentative process that occurs underanaerobic conditions.28 However, sensory impacts can be ameliorated bytransferring the berries to air (0°C) before sale to reduce ethanol and acetal-dehyde levels. Conditions for storing berry fruits under CAs are listed inTable 9.4.

9.4.2 Modified atmosphere packaging

Modified atmosphere packaging is a packaging technology developed toextend shelf life by blanketing a product with a specialized atmosphere tomaintain freshness within the package. Generally CO2 is increased and O2

levels are decreased to slow the metabolic activity of the fruit. Berries pre-served by this technology retain their quality and nutritional value longerthan those stored in air. MAP inhibits the growth of many pathogens andexpands marketing options by increasing the time that fresh berries canspend in transit and retail outlets awaiting purchase. Whereas CAs involve

Table 9.4 Controlled Atmosphere Requirements for Berries

Berry fruitTemperature

(°C)Percent

O2

PercentCO2 Commercial use

Blackberry 0.5 to 0 5–10 10–20 Gases are sealed within pallet covers during transport

Blueberry 0.5 to 0 1–10 10–15 Sometimes used during transport

Cranberry (Vaccinium sp.)

2.0 to 4.0 1–2 0–5 Not used commercially

Grapes 0.5 to 0 5–10 15–20 Sometimes used during transport to replace sulfur dioxide for decay control

Raspberry 0.5 to 0 5–10 15–20 Gases are sealed within pallet covers during transport

Strawberry 0.5 to 0 5–10 15–20 Gases are sealed within pallet covers during transport

Source: Adapted from Salunkhe and Desai, 1984,79 Kader,80 and Haffner et al.81



continuous infusion of carefully controlled gases, MAP is generally aone-time adjustment of the atmosphere combined with a packaging materialthat prevents the newly introduced gases from being lost. Modified atmo-spheres can also be created passively by a fruit’s own respiration as it con-sumes O2 and gives off CO2 within a permeable packaging material.

Berries tend to lose moisture when the relative humidity decreases duringstorage; however, most MAP films are designed to be impermeable to water.This increases the possibility that condensation will form on the inside of thepackage during temperature fluctuations, allowing decay-causing microor-ganisms to grow. Methods for dispersing condensed water have been devel-oped, such as using surface treatments to spread the liquid into a uniformlythin film, or adding a natural adsorbent such as clay to retain excess moisture.41

A variety of MAP designs are being developed in response to the grow-ing demand for fresh market fruit. Selecting favorable conditions for MAPdepends on the characteristics of the produce (e.g., respiration rate, mass,temperature requirements), as well as properties of the packaging (e.g.,surface area, film thickness, perforation size). For MAP technologies to beeffective, the packaging must be able to contain the desired atmosphere forthe duration of transport and storage. A popular system available commer-cially for strawberries is a pallet box bulk unit wrapped with a barrier plasticfilm to hold the selected gases (Figure 9.4). Cartons that contain liners can

Figure 9.4 Pallet box wrapped with plastic film to contain the modified atmosphereduring transport of strawberries. (Photo provided by Elizabeth Mitcham, Universityof California–Davis.)



also retain MAP gases. Packaging materials that control the oxygen trans-mission rate (OTR) permit commodities with high respiration rates to receiveenough O2 to prevent fermentation from occurring. Microperforated filmsprovide a high OTR by allowing a more rapid exchange of gas than tradi-tional plastic films. Grapes packaged with 15 kPa O2 and 10 kPa CO2 in amicroperforated polypropylene film (35 µm) were found to have a lowerincidence of B. cinerea infection than the control clusters (60 days at 0°C).42

9.4.3 Effects of CA and MAP

The primary use of CA storage and packaging for berry fruit is to lower therespiration rate until the product can be sold. By slowing biochemical changesthat occur during postharvest handling and storage, the shelf life of the berriescan be significantly extended. CA and MAP technologies reduce the need forpostharvest fungicides and insecticides, and allow fully ripe fruit to be har-vested. After transport, when the berry fruits are removed from CA conditionsand exposed to air for marketing, residual effects may persist. Reduced respi-ration rates, decreased ethylene production, and delayed incidence of decaywere still present 1 week after strawberries were removed from reduced O2

storage.43 However, there is a critical point beyond which the fruit is damagedby the low O2 conditions. Thresholds for each product must be determinedindividually to ensure quality while being stored under CA conditions.

Controlled atmosphere storage can offset the effects of ethylene produc-tion, which naturally occurs in fruits. Ethylene is a colorless gas that triggersripening of fruit. Its presence allows some produce to be harvested beforeit is fully ripe, since the ripening process will occur during storage andtransit. Fruits that are sensitive to ethylene are called climacteric. Strawber-ries are nonclimacteric fruits and must be harvested with at least 75% oftheir surface already red, since the color intensity will not continue toincrease after harvest.28 Most berry fruits are nonclimacteric, and neitherproduce nor respond to ethylene in any significant way. Blueberries are anexception, since they can continue to ripen in the presence of ethylene;however, blueberries must be harvested almost fully ripe to attain acceptableflavor for fresh market sales. Oxygen concentrations of less than 5% areassociated with decreased ethylene production, while CO2 concentrations ofless than 1% result in elevated ethylene levels.38

9.5 Edible coatings for extending the shelf life of berriesEdible coatings can be applied as a barrier to extend the shelf life of freshmarket berries. Although waxes have been used for centuries to preventmoisture loss and protect perishable fruits from damage and contamination,new coatings with superior properties are continually being developed. Edi-ble films can be fortified with vitamins, probiotics, and antioxidants toimprove the nutritional value of the food. They can also be formulated withantimicrobial agents to protect against foodborne pathogens. Coatings and



films are biodegradable and may even lead to the decreased use of packagingmaterials. In some respects, edible coatings can be considered to be similarto MAP, since they both create a micro-controlled atmosphere around theberries, thereby modifying gas exchange with the surrounding air.

9.5.1 Developing coatings and films

An edible coating can be described as a food-safe solution that is directlyapplied to the surface of a product. Edible films are prepared separately asthin layers and then applied to the outside of a food as a barrier. A varietyof different films and coatings have been developed for protecting fruits,including polysaccharides such as starch, seaweed extracts, chitinous mate-rial, and cellulose derivatives.44 Protein and lipid coatings have also beenproduced. However, these are generally not used for berries. Ideally theseedible films should be transparent and should not interfere with the aromaand flavor of the food they protect. They should be easy to apply in a uniformlayer and they should adhere tightly to the food without transferring tosurrounding materials.

Edible films composed of polysaccharide compounds are usually hydro-philic, providing a barrier against oxygen and hydrophobic compounds suchas lipids. Unfortunately polysaccharides do not prevent the migration ofwater from fruit to the coating. To design a film with water-barrier propertiescapable of reducing moisture loss, it would be necessary to incorporatehydrophobic compounds such as oils or waxes. Fatty substances tightly alignat the molecular level to effectively repel water, but are sometimes difficultto stabilize when forming film barriers. Bilayer coatings can contribute valu-able characteristics from both hydrophilic and hydrophobic moieties. Coat-ings are capable of extending the shelf life of fresh fruit by reducing moistureloss and slowing the ripening process. However, to protect against the devel-opment of off-flavors, coatings should not be applied at a thickness thatprevents aerobic respiration from occurring within the encased cells.

9.5.2 Incorporating antimicrobial agents

Edible coatings can seal the surface of a fruit, sometimes creating a low O2

environment that is favorable for anaerobic pathogens such as C. botulinum.Incorporating antimicrobial compounds into coatings can inhibit unwantedmicrobial growth. Chitosan is derived from the shells of shrimp and crabs,and is known to exhibit antifungal activity in strawberries and raspberries.45

Fresh strawberries coated with a 2% chitosan-based solution demonstratedactivity against the fungi Cladosporium sp. and Rhizopus sp. (5°C, 50% relativehumidity). Coated strawberries experienced less weight loss and had loweraerobic microorganism counts than untreated controls.46

Edible films should not be detectable on the surface of a berry. Acid-dis-solved chitosan coatings have been perceived as bitter and astringent whenapplied to fresh strawberries (Fragaria ananassa). Sensory testing performedon chitosan solutions dissolved in acetic acid (0.6%) or lactic acid (0.6%)



indicated that chitosan coatings improved the appearance of the strawberrieswithout affecting their flavor, sweetness, or firmness.47 Chitosan solutionswere also evaluated for antifungal activity as preharvest sprays rather thanpostharvest coatings. Strawberry plants received chitosan treatments 5 daysbefore harvest, when the fruit was not yet fully red. After harvest, the berrieswere challenged with B. cinerea. Chitosan-sprayed berries experienced sig-nificantly less postharvest decay than the controls and their texture remainedfirmer throughout storage (4 weeks at 3°C).48

Chitosan coatings containing essential oils can also be inhibitory to fungi.49

When anise was combined with chitosan, the resulting coating was able toinhibit the growth of B. cinerea on strawberries.50 Antibacterial activity can alsobe incorporated into chitosan films by adding an antimicrobial enzyme suchas lysozyme. A film matrix prepared with chitosan and lysozyme retainedactivity against E. coli and Streptococcus faecalis without affecting water vaporpermeability, although the tensile strength and percent elongation values werefound to decrease with increasing lysozyme concentrations.51

9.5.3 Other novel coatings

New films and coatings for preserving berry fruit are always being studied.An edible coating based on aloe vera gel was evaluated for its ability toextend the shelf life of grapes during storage. Grape clusters coated withaloe vera gel experienced less softening, rachis browning, and color changesthan untreated controls (35 days at 1°C).52 Microbial decay caused by yeastand molds was also significantly decreased in aloe vera-coated berries with-out negatively impacting taste, aroma, or flavor characteristics.

Calcium has been added to edible coatings to control postharvest decayin raspberries, strawberries,53 and blueberries.54 Wheat gluten coatings andfilms were evaluated for their ability to extend the postharvest life of freshstrawberries, with promising antimicrobial results and consumer acceptance.55

Currently there is little demand for coatings designed to extend the shelflife of fresh market berry fruit. Berries are frequently packed right in thefield with as little handling as possible. This process does not encourage thedevelopment of edible coatings. Additional issues surrounding the produc-tion of edible films for berries involve manufacturing as well as formulationproblems. It is thought that coatings and films might not adhere to the foodand other film components might migrate inside. There is also a negativepublic perception concerning chemical additives on fresh fruit. These arejust a few of the concerns that keep this technology from becoming morecommon in fresh market sales.

9.6 Other technologies or treatments for shelf life extensionConsumers desire safe, healthy foods that are minimally processed andready to eat. Fresh berry fruits fall into this category as a highly nutritiouschoice. Controlling postharvest diseases generally requires fungicides.



However, the current trend toward using fewer chemicals in food, togetherwith growers’ concerns over fungicide-resistant pathogens, have led to thesearch for alternative treatments. To maintain the quality of freshly har-vested fruits such as berries, a variety of technologies are being evaluated.Low-dose irradiation has been successful in inhibiting the postharvestgrowth of gray mold on strawberries. Control of fungi has also been accom-plished by harnessing other organisms and employing them as biocontrolagents.

9.6.1 Irradiation

The use of ionizing radiation for extending the shelf life of fruits and vege-tables has received considerable attention. Gamma irradiation (2 kGy) inhib-ited Rhizopus sp. and Botrytis sp. decay in grapes during shipping andstorage56 and may offer an alternative to sulfur dioxide fumigation. Berryfirmness and other sensory qualities were not affected by the process.Gamma irradiation of fresh strawberries also significantly delayed thegrowth of molds.57 However, consumer acceptance of irradiated foodremains low. A study conducted in 2000 determined that only 50% of thepeople polled would purchase an irradiated food product.58

9.6.2 Biocontrol agents

The current trend to reduce the quantity of chemicals applied postharvestto berry fruit is being driven by environmental and health concerns. Theconcept of applying environmentally friendly biocontrol agents is often moreappealing to consumers than treating fresh produce with chemicals. Aure-obasidium pullulans, a yeast-like fungus, was found to suppress the growthof B. cinerea and R. stolonifer on strawberries and grapes.59,60 Aureobasidiumoutcompetes other fungi for nutrients, thereby preventing the growth ofdecay-causing fungi, even at refrigerator temperatures. Trichoderma isolateswere able to control anthracnose (Colletotrichum acutatum) and gray mold (B.cinerea) on strawberries with the same effectiveness as the chemical fungicidefenhexamid.61 Metschnikowia fructicola also inhibited postharvest rots instrawberries more effectively than fenhexamid.62 Bacillus pumilus andPseudomonas fluorescens were also able to suppress B. cinerea on strawberries.63

However, biological controls have not achieved widespread use in the freshmarket berry sector.

9.6.3 Other treatments

Researchers continue to search for new methods to extend the shelf life offresh berry fruit. For highbush blueberries (Vaccinium corymbosum L.), theethylene inhibitor 1-methylcyclopropene (400 nl/l) was effective in slowingpostharvest ripening when used in combination with CA storage (10 to 15 kPa



O2 and 10 kPa CO2) at 0°C for 12 weeks.64 Another form of storage thatalters the atmosphere surrounding the fruit is hypobaric storage. Reducedpressures (0.50 atm) were effective against postharvest rots such as B.cinerea and Rhizopus in strawberries and grapes.65 Low levels of ultravioletC (UV-C) light (1.0 kJ/m2) was also able to reduce the incidence of post-harvest Botrytis decay on strawberries significantly better than in nonirra-diated controls.66

Jasmonates are naturally occurring compounds that activate antifun-gal genes in plants. When methyl jasmonate was applied as a postharvesttreatment on strawberries and raspberries, B. cinerea was significantlydecreased.67,68 Eugenol, thymol, and menthol (0.5 ml) were individuallytested for their ability to preserve grapes for 35 days when used incombination with MAP (1.4 to 2.0 kPa CO2 and 10.0 to 14.5 kPa O2). Eachtreatment was found to be effective in inhibiting fungal decay caused byB. cinerea. In addition, weight loss and color changes were slowed andfirmness was retained; however, there were noticeable changes inaroma.69

9.7 ConclusionThe quality of fresh market berries after harvest depends to a large extenton postharvest care. The cumulative effects from handling, storing, andtransporting to market are critical in delivering a product that appeals toconsumers.

Mechanized harvesting, sorting, and packaging technologies must con-tinue to improve if damage to fruit is to be minimized. Until then, thelongest shelf life will be achieved when berries are harvested by handdirectly into retail containers. Each berry fruit has different postharveststorage and transport requirements. These are summarized in Table 9.5.The short shelf life makes shipping perishable fruits long distances forfresh market sale difficult. Spoilage of fresh berry fruit is sometimes diffi-cult to measure. Defects can include immature berries, which are less sweetat the time of harvest, splitting of berries (from overripening), and shriv-eling (from age and water loss). Overripe blueberries may appear uninjuredwhen picked, but they do not transport well, arriving in an unacceptablecondition for the consumer.

In a hungry and increasingly competitive world, reducing postharvestfood losses is a worthy agricultural goal. Even a partial reduction couldsignificantly reduce the overall cost of food production and lessen our depen-dence on marginal land and other scarce resources. With improvements instorage technologies and the increase in global trade, today’s consumerexpects to find fresh berries available for purchase outside of the local harvestseason. Proper postharvest handling, storage, and treatment of fresh marketberry fruit will ensure that this commodity remains available worldwidethroughout the year.


Chapter 9: Postharvest handling, storage, and treatment 283Ta

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66. Nigro, F., Ippolito, A., Lattanzio, V., Di Venere, D., and Salerno, M., Effect ofultraviolet-C light on postharvest decay of strawberry, J. Plant Pathol., 82, 29,2000.

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70. Ellis, M.A., Converse, R.H., Williams, R.N., and Williamson, B., Compendiumof Raspberry and Blackberry Diseases and Insects, APS Press, St. Paul, MN, 1991,chap. 1.

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72. Milholland, R.D., Anthracnose fruit rot (ripe rot), in Compendium of Blueberryand Cranberry Diseases, Caruso, F. and Ramsdell, D., Eds., APS Press, St. Paul,MN, 1995.

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Part III

Processing technologies for developing value-added berry fruit products



291

chapter 10

Freezing process of berries

Yanyun Zhao

Contents

10.1 Introduction ............................................................................................... 29210.2 Principles of the freezing process .......................................................... 293

10.2.1 Freezing steps and freezing rate................................................ 29310.2.2 Chemical changes......................................................................... 29410.2.3 Volume and texture changes ...................................................... 29410.2.4 Microbial changes ........................................................................ 29510.2.5 Nutrients of frozen berries ......................................................... 295

10.3 Methods for freezing berries................................................................... 29610.3.1 Preparation of berries for freezing ............................................ 29610.3.2 Air-blast freezer ............................................................................ 29810.3.3 Spiral belt freezer ......................................................................... 29810.3.4 Fluidized bed freezer................................................................... 30110.3.5 Liquid immersion and cryogenic freezer................................. 301

10.4 Innovation in the freezing process of berries....................................... 30310.4.1 Vacuum impregnation pretreatment

using cryoprotectants or cryostabilizers .................................. 30310.4.2 Edible coatings to improve integrity

and control drip loss of frozen berries ..................................... 30310.5 Ensuring the quality of frozen berries .................................................. 304

10.5.1 Quality standards of frozen berries .......................................... 30410.5.2 Rapid freezing to obtain small regular

ice crystal formation .................................................................... 30510.5.3 Prevention of quality deterioration during

frozen storage ............................................................................... 30510.5.3.1 Ice crystal size and shape............................................. 30510.5.3.2 Moisture migration........................................................ 30710.5.3.3 Sublimation..................................................................... 307



10.5.3.4 Solute crystallization and pH change ........................ 30710.5.3.5 Freeze/thaw cycles........................................................ 307

10.5.4 Packages for limiting moisture loss and gas transfer ............30810.6 Applications of frozen berries ................................................................ 30810.7 Conclusion.................................................................................................. 310References ........................................................................................................... 310

10.1 Introduction

The market of frozen berries is huge. In the United States, the volume offrozen berries, including blackberries, blueberries, boysenberries, red andblack raspberries, and strawberries, was about 478, 415, 434, 391, and 698 millionpounds in 2000, 2001, 2002, 2003, and 2004, respectively (Table 10.1).

Freezing is the most traditional method of preserving berries. Mostberries can be frozen satisfactorily, with long shelf life and minimal impactson quality and nutritional loss. However, the quality of the frozen berrieswill vary with the nature of the fruit, stage of maturity, and the type offreezing method and packaging. Selecting fruit with a firm texture andwell-developed flavor, and freezing and storing following appropriate prac-tices are critical to the final product quality.

In addition to serving as a food preservation method, the freezing pro-cess is also a commonly recommended pretreatment procedure prior to otherberry processes. Freezing is recommended prior to juice processing becauseit disrupts tissue cell structure for easy juice extraction, thus increasing theyield. Frozen berries are used for making dehydrated product because ofthe enhanced removal of moisture during drying. Moreover, frozen berriesare used to make berry jams and preserves because freezing facilitates easycooking. Hence, understanding the principles of the berry freezing process,the critical quality controls, and selection of appropriate freezing methodsand storage conditions is critical for achieving high quality product andimproving economic efficiency. This chapter covers the basic principles of

Table 10.1

Stocks of Frozen Berries in Cold Storage (all warehouses)

Type of berry 2000 2001 2002 2003 2004

Blackberries 23,470 22,171 22,796 23,395 42,032Blueberries 85,383 100,526 88,705 76,834 77,331Boysenberries 4,537 3,152 3,171 1,502 3,674Black raspberries 1,559 2,840 2,612 1,058 1,814Red raspberries 53,824 42,162 50,660 40,887 89,527Total strawberries 309,551 243,716 266,376 247,173 483,466Total frozen berries 478,324 414,567 434,320 390,849 697,844

All data shown in thousands of pounds.

Source

: Data are from the National Agricultural Statistics Service (NASS), AgriculturalStatistics Board, U.S. Department of Agriculture, Washington, D.C.


Chapter 10: Freezing process of berries 293

the freezing process, freezing methods applicable for berries, critical qualityand safety control procedures, and common food applications of frozenberries.

10.2 Principles of the freezing process

The principles of the freezing process are based on (1) low temperature, (2) reducedwater activity due to ice formation and high concentrations of solutes, and(3) blanching of some fruits and vegetables prior to freezing. Several reac-tions take place during the freezing process, including (1) chemical reactions,(2) effects on the tissue structures of plant products, and (3) biologicalreactions, typically microbial reactions. These reactions are closely associatedwith various properties of the food, such as its chemical composition andmaturity, and are directly affected by conditions of the freezing process, suchas freezing rate and method, packaging, and storage conditions.

10.2.1 Freezing steps and freezing rate

Freezing consists of lowering the temperature of a food to

−

18

°

C or less,which

crystallizes some of the water and solutes. There are two steps infreezing process:

1

• Supercooling. When the water temperature is below the freezingpoint and crystallization does not occur, the water is “supercooled.”Supercooling can occur when ice nucleation is not present and no icecrystals form.

• Crystallization of water. Formation of a systematically organizedsolid phase from a solution and solute.

The freezing rate is defined as the degree of temperature reduction in afood per minute (

°

C/min). It directly determines the quality of the frozenproduct and is affected by many product and processing factors. For fruits,the extent of cell wall rupture can be controlled by the freezing rate. Forrapid freezing, with a freezing rate greater than 4

°

C/min, a large numberof small ice crystals form. These small ice crystals produce less cell wallrupture than slow freezing (freezing rate less than 4

°

C/min), in which largeice crystals form, producing more cell wall ruptures. Factors affecting thefreezing rate include

• Temperature difference between the food product and the coolingmedium.

• Air velocity when cold air is used as a cooling agent.• Product characteristics, such as composition, structure, size, and shape.• Contact between the product and cooling medium.• Initial product temperature.• Type of freezing equipment used.



10.2.2 Chemical changes

After harvesting, berries continue to undergo chemical changes that cancause spoilage and quality deterioration. Fresh fruits should be frozen assoon after harvest as possible and at their peak of ripeness in order toproduce high-quality frozen products. When berries are frozen, chemicalchanges can occur, including concentration of solutes and chemicals in theliquid phase, enzyme activity, and oxidative reactions.

During freezing, as water migrates to ice crystals, the nonaqueous mate-rials (solutes) become concentrated in the residual unfrozen water. The resid-ual unfrozen water undergoes changes in pH, titratable acidity, ionicstrength, viscosity, freezing point, surface and interfacial tensions, and oxi-dation-reduction potential. In addition, carbon dioxide and oxygen areexpelled from the solution/water structure and water/solute interactionsare altered, macromolecules are forced closer together, and eutectic forma-tion occurs. As water molecules are removed from solution and depositedonto ice crystals, various solutes increase in concentration, eventually reach-ing their saturation point, then simultaneous ice crystallization and solutecrystallization becomes possible.

1–3

Enzymes present in berries can cause the loss of color, nutrients, andflavor in frozen products. Enzymes must be inactivated to prevent suchreactions from occurring. “Blanching,” a process in which fruits and vege-tables are subjected to hot water or steam for a short time and then cooledbefore freezing, is usually used to inactivate enzymes in vegetables and somefruits. The major problem associated with enzymes in berries is the devel-opment of browning discoloration and the loss of vitamin C. Since frozenberries are sometimes consumed raw, instead of blanching, enzymes in fro-zen berries can be controlled by using chemical compounds that interferewith deteriorative chemical reactions. Ascorbic acid is the most commoncontrol chemical used for this purpose, and it may be used in its pure formor in commercial mixtures with sugars. Other methods that may be utilizedinclude soaking the fruit in a dilute vinegar solution or coating the fruit withsugar and lemon juice. However, these latter methods do not prevent brown-ing as effectively as treatment with ascorbic acid.

Another group of chemical changes that can take place in frozen prod-ucts is the development of rancid oxidative flavors due to reaction of thefrozen product with air (oxygen). When berries are frozen, the solutes aremore concentrated, and thus can be more easily oxidated. This reaction canbe controlled by using packaging materials that are oxygen barriers, to limitthe oxygen passing into the product. Vacuum packaging is another approachto reduce oxidative changes.

10.2.3 Volume and texture changes

Fresh berries contain about 85% to 90% water. Water and other chemicalsubstances are held within the fairly rigid cell walls, which give structureand texture to the fruit. When water forms ice during freezing, it expands.



Pure water expands about 9% when freezing at 0

°

C. Most foods expand, butto a lesser extent than pure water, because other components are contracting.The overall extent of volume expansion for a given frozen fruit depends onmany factors, including fruit composition, the fraction of unfrozen water,the temperature at which the fruit is frozen and stored, the size of the icecrystals, and cooling prior to and after freezing. The volume changes infrozen berries in turn affect the texture of the thawed product.

Freezing damage in plant tissue systems includes disruption of meta-bolic systems, dislocation of enzyme systems, loss of turgor due to cell walland cell membrane damage, and permanent transfer of intracellular waterto the extracellular fluid through osmosis.

2

These cannot be reversed uponthawing. If the ice crystals rupture the cell wall, the texture of the fruit, whenthawed, will be much softer than when it was raw. The larger the ice crystalsformed, that is, the more the volume changes, the more the texture changesin thawed fruit. Drip loss, defined as the amount of liquid collected whenfrozen food is thawed, has been used as a indicator of the quality of frozenfood. Drip loss is a direct measure of volume changes in frozen food andthus the texture of thawed product.

10.2.4 Microbial changes

The freezing process does not actually destroy the microorganisms that maybe present on berries. Instead, during freezing and frozen storage, somemicroorganisms are killed, some are injured, and others survive. The growthof microorganisms is dependent on temperature. Pathogenic microorgan-isms usually do not grow at temperatures below 5

°

C, and most other micro-organisms do not grow at temperatures less than

−

5

°

C. Thus there is agradual decline in the number of microorganisms during freezing. However,sufficient populations are still present to multiply. Hence food preservationby freezing relies on inhibition of the growth of any surviving microorgan-isms. Controlling the temperature during freezing and storage is critical toprevent the growth of existing microorganisms. In addition, when blanchingis applied prior to freezing, it can also destroy some microorganisms.

10.2.5 Nutrients of frozen berries

When properly done, freezing may potentially preserve the greatest quantityof nutrients. To maintain the nutritional quality of frozen berries, it is essen-tial to freeze the fruit fast by using appropriate freezing methods, store thefrozen product at

−

18

°

C, and use it within suggested storage times.The U.S. Food and Drug Administration (FDA) published its final rule

about the nutrition profiles of frozen fruits and vegetables in the

FederalRegister

on March 25, 1998.

4

In an effort to evaluate the nutrient content offrozen fruits and vegetables compared to raw fruits and vegetables, theagency reviewed both the American Frozen Food Institute’s (AFFI) supple-mental data

5

and similar data from the U.S. Department of Agriculture(USDA). The nutrient profiles of selected raw fruits and vegetables and



frozen, single-ingredient versions of the same fruits and vegetables revealedrelatively equivalent nutrient profiles.

In fact, some data show that the nutrient content for certain nutrientswas higher in the frozen version of the food than in the raw version of thefood. This is probably due to the fact that unprocessed (i.e., raw) fruits andvegetables may lose some of their nutrients over time under certain storageconditions.

4

10.3 Methods for freezing berries

Berries may be frozen individually, packed in dry sugar or syrup (blockfrozen berries), or crushed into purees before freezing, depending on thefinal application of the finished product. Different types of freezers, includ-ing air-blast, spiral, fluidized bed, liquid immersion, spray, plate, and cryo-genic, are available for specific applications. The type of freezer selectedshould be based on freezing rate, cost, function, and feasibility. The freezingrate directly determines final product quality. Financial considerationsshould take into account both the capital and running costs of the equipmentand also projected losses from product damage and dehydration. Functionalconsiderations include whether the freezer is required for continuous orbatch operation and whether the freezer is physically able to freeze theproduct. The feasibility of operating the freezer in a specific plant locationshould also be considered. For processing individual quick frozen (IQF)berries, air-blast, spiral, and fluidized bed freezers can be utilized. Air-blastfreezers are also the most common type used for freezing packed berries.The following sections discuss preparation procedures for freezing berriesand the major types of freezers used.

10.3.1 Preparation of berries for freezing

Depending on the varieties and harvest times, berries vary significantly inflavor, color, and firmness. Only the berries harvested at peak quality shouldbe used for freezing to ensure final product quality and safety. Full-flavored,ripe berries of about the same size and with tender skins should be selected.After berries are harvested either by hand or machine, field debris shouldbe removed, usually using a blower. The berries are then sorted, washed,and drained. For strawberries, stems need to be removed before sorting andwashing. For some other berries, such as blueberries, steam blanching for 1minute and cooling immediately may be applied if desired, since preheatingin steam tenderizes the skin and makes a better flavored product. Figure 10.1is a general flow diagram of the freezing process for berries.

Berries may be individually quick frozen, packed in sugar syrup or drysugar, or dry packed without sugar before freezing.

6,7

In syrup packing,berries are well covered with syrup or juice during freezing and thawing toprevent darkening of the berries at the top. Crumpled freezer paper can beplaced under the lid of a rigid container to hold fruit under the syrup or juice.



When plastic bags are used, air has to be removed to prevent oxidation. Insugar syrup packing, sugar is first dissolved in water. If hot water is used,cool the syrup to about 21

°

C before using. The syrup can be made ahead oftime and kept in the refrigerator.

For sugar packing, one part sugar by weight is added to four parts fruitby weight, making the fruit sweet enough and preserving its quality. Thesugar and fruit are gently mixed until juice is drawn out and the sugar isdissolved. The fruit and juice are then packed in pails or drums. The drumsare usually lined with plastic bags or a piece of crumpled moisture and vaporresistance paper is placed on top to hold the fruit in juice.

In unsweetened packing, the fruit is placed in containers without liquidor sweetening, or may be covered with water containing ascorbic acid toprevent browning discoloration. Some berries, such as strawberries, may be

Figure 10.1

A general flow diagram for the freezing process of berries.

Raw fruits(choice of cultivars and crop production)

Maturity assessment

Picking and transportation

Inspection

Preparation before freezing (cleaning/washing,sorting, size grading, slicing, etc.)

Inspection again

Pack in sugar, syrup, or dried pack as needed

Freezing

Frozen storage at −23oC

Transportation

Marketing



more mushy when packed without sugar. It is best to cover light-coloredberries with water containing ascorbic acid. Berries may be crushed or slicedin their own juice without sweetening and then pressed into the juice or waterwith a small piece of crumpled paper, similar to syrup or sugar packing.

The selection of a packing method is based on market demand, profit-ability, and the quality of the fruit. Generally syrup packing is best for dessertuse, and dry sugar and unsweetened packing are best for most cookingpurposes. Details on the specific applications of different types of packedfrozen berries are discussed in Section 10.6. Table 10.2 describes suggestedpacking methods for different varieties of berries.

When berries are packed, the pallets of pails or drums are taken into afreezer at

−

28

°

C under forced-air circulation. It takes about 5 days to freezethe packed berries, depending on the type of freezer used.

10.3.2 Air-blast freezer

In air-blast freezers, cold air vigorously circulates, enabling freezing to pro-ceed at a moderately rapid rate. There are batch-type and continuous sys-tems. In the batch-type system, fruit is loosely placed on trays that are placedon carts or freezing coils in a low temperature room with cold air blowingover the product.

8

In some systems, the cold air is circulated by means oflarge fans, while in other systems the air is blown through refrigerated coilslocated either inside the room or in an adjoining blower room.

The continuous system, such as tunnel freezing, is possibly the mostcommonly used freezing system. In tunnel freezing, a long, slow-moving meshbelt passes through a tunnel or enclosure containing very cold moving air.The speed of the belt varies according to the time necessary to freeze theproduct. Usually the cold air is introduced into the tunnel at the opposite endfrom where the product to be frozen enters, that is, the air flow is usuallycounter to the direction of product flow. The temperature of the air is usuallybetween

−

18

°

C and

−

34

°

C. The air velocity varies from 30 m/min to 1067m/min; 762 m/min is considered a practical and economical air velocityat

−

29

°

C.

8

To achieve rapid freezing, it is necessary to recirculate a rather largevolume of the air in order to obtain a relatively small increase in the temper-ature of the air as it touches and leaves the product. Air has a very low specificheat, thus a large volume must be carefully distributed through the system.

Air-blast freezer is economical and capable of accommodating foods ina variety of sizes and shapes, and it can be used by berry processors forprocessing both IQF and pack-frozen berries. However, it can result in prod-uct with excessive dehydration if conditions are not carefully controlled.

8

10.3.3 Spiral belt freezer

Spiral belt freezers use a belt that can be bent laterally. The original spiralbelt design uses a spiraling rail system to carry the belt, with a central drumthat drives the belt through friction at the belt edge.



Tabl

e 10

.2

Type

s of

Pac

ks C

omm

only

Use

d f

or F

reez

ing

Ber

ries

Vari

ety

of b

erry

Sam

ple

pre

par

atio

nTy

pe

of p

acks

Am

ong

mos

t fir

m

berr

ies:

bl

uebe

rrie

s,

eld

erbe

rrie

s,

huck

lebe

rrie

s

Sele

ct f

ull-

flav

ored

, rip

e be

rrie

s w

ith

unif

orm

siz

e an

d t

end

er

skin

s; s

ort,

was

h, a

nd d

rain

be

rrie

s; if

des

ired

, ste

am

blan

chin

g fo

r 1

min

ute

and

coo

l im

med

iate

ly t

o te

nder

ize

skin

an

d m

ake

bett

er fl

avor

ed

prod

uct.

Syru

p pa

ck: P

ack

berr

ies

into

con

tain

ers

and

cov

er w

ith

cold

40%

syr

up.

Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Uns

wee

tene

d p

ack:

Tra

y pa

ck o

r pa

ck b

erri

es in

to c

onta

iner

s. L

eave

he

adsp

ace,

sea

l, an

d f

reez

e.C

rush

ed o

r pu

ree:

Cru

sh o

r pr

ess

berr

ies

thro

ugh

a fin

e si

eve

for

pure

e.

To 2

lb. c

rush

ed b

erri

es o

r pu

ree,

ad

d 1

to 1

1

/

2

cup

s of

sug

ar, d

epen

din

g on

tart

ness

of t

he fr

uit.

Stir

unt

il su

gar i

s d

isso

lved

. Pac

k in

to c

onta

iner

s.

Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Am

ong

the

mos

t so

ft b

erri

es:

blac

kber

ries

, bo

ysen

berr

ies,

d

ewbe

rrie

s,

loga

nber

ries

, yo

ungb

erri

es

Sele

ct fi

rm, p

lum

p, a

nd f

ully

rip

e be

rrie

s w

ith

glos

sy s

kins

, sin

ce

gree

n be

rrie

s m

ay c

ause

of

f-fl

avor

; sor

t be

rrie

s in

to

unif

orm

siz

es, a

void

ing

infe

cted

an

d in

jure

d f

ruit

; rem

ove

any

leav

es; w

ash

and

dra

in b

erri

es.

Syru

p pa

ck: P

ack

berr

ies

into

con

tain

ers

and

cov

er w

ith

cold

40%

or

50%

sy

rup,

dep

end

ing

on th

e sw

eetn

ess

of th

e fr

uit.

Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Suga

r pa

ck: T

o 1

lb. o

f be

rrie

s, a

dd

3

/

4

cup

of

suga

r. Tu

rn b

erri

es o

ver

unti

l mos

t of

the

sug

ar is

dis

solv

ed. F

ill c

onta

iner

s. L

eave

hea

dsp

ace,

se

al, a

nd f

reez

e.U

nsw

eete

ned

pac

k: P

ack

berr

ies

into

con

tain

ers.

Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Cru

shed

or

pure

e: C

rush

or

pres

s th

roug

h a

siev

e fo

r pu

ree.

To

each

2

lb. o

f cr

ushe

d b

erri

es o

r pu

ree,

ad

d 1

cup

sug

ar. S

tir

unti

l sug

ar is

d

isso

lved

. Pac

k in

to c

onta

iner

s. L

eave

hea

dsp

ace,

sea

l, an

d f

r eez

e.R

aspb

erri

esSe

lect

fully

rip

e, ju

icy

berr

ies;

sor

t, w

ash

care

fully

in c

old

wat

er, a

nd

dra

in t

horo

ughl

y.

Suga

r pa

ck: T

o 1

lb. o

f be

rrie

s ad

d

3

/

4

cup

of

suga

r an

d m

ix c

aref

ully

to

avoi

d c

rush

ing.

Put

into

con

tain

ers.

Lea

ve h

ead

spac

e, s

eal,

and

fr e

eze.

Syru

p pa

ck: P

ut b

erri

es in

to c

onta

iner

s an

d c

over

wit

h co

ld 4

0% s

yrup

. L

eave

hea

dsp

ace,

sea

l, an

d f

reez

e.

(

Con

tinu

ed

)



Tabl

e 10

.2 (

Con

tinu

ed)

Type

s of

Pac

ks C

omm

only

Use

d f

or F

reez

ing

Ber

ries

Vari

ety

of b

erry

Sam

ple

pre

par

atio

nTy

pe

of p

acks

Uns

wee

tene

d p

ack:

Put

ber

ries

into

con

tain

ers.

Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Cru

shed

or

pure

e: C

rush

or

pres

s th

roug

h a

siev

e fo

r pu

ree.

To

2 lb

. of

crus

hed

ber

ries

or

pure

e, a

dd

3

/

4

to

1 cu

p of

sug

ar, d

epen

din

g on

the

sw

eetn

ess

of t

he f

ruit

. Mix

unt

il th

e su

gar

is d

isso

lved

. Put

into

co

ntai

ners

. Lea

ve h

ead

spac

e, s

eal,

and

fre

eze.

Stra

wbe

rrie

sW

hole

frui

t or

slic

ed; c

rush

ed fr

uit

may

be

used

, thu

s d

iffer

ent

hand

ling

may

be

appl

ied

.W

hole

ber

ries

: Sel

ect fi

rm, r

ipe,

red

be

rrie

s w

ith

a sl

ight

ly t

art

flav

or.

Slic

ed b

erri

es: S

lice

larg

e be

rrie

s in

to

3

/

4

inch

or

othe

r th

ickn

ess

base

d o

n ne

eds

or c

rush

for

fas

t fr

eezi

ng.

Ber

ries

sho

uld

be

sort

ed, w

ashe

d

in c

old

wat

er, a

nd w

ell d

rain

ed,

and

hul

ls r

emov

ed.

Syru

p pa

ck: P

ut b

erri

es in

to c

onta

iner

s an

d c

over

wit

h co

ld 5

0% s

yrup

. L

eave

hea

dsp

ace,

sea

l, an

d f

reez

e.Su

gar

pack

: Ad

d

3

/

4

cup

of s

ugar

to 1

lb. o

f str

awbe

rrie

s. S

tir

unti

l mos

t of

the

suga

r is

dis

solv

ed o

r le

t sta

nd fo

r 15

min

utes

. Put

into

con

tain

ers.

L

eave

hea

dsp

ace,

sea

l, an

d f

reez

e.U

nsw

eete

ned

pac

k: T

ray

pack

or

pack

into

con

tain

ers.

Lea

ve h

ead

spac

e.

For

bett

er c

olor

, cov

er w

ith

wat

er c

onta

inin

g as

corb

ic a

cid

. Sea

l and

fr

eeze

.Sl

iced

or

crus

hed

: Slic

e or

cru

sh p

arti

ally

or

com

plet

ely.

To

1 lb

. of b

erri

es

add

3

/

4

cup

of

suga

r an

d m

ix w

ell.

Pack

into

con

tain

ers.

Lea

ve

head

spac

e, s

eal,

and

fre

eze.

Pure

e: P

ress

ber

ries

thr

ough

a s

ieve

. To

2 lb

. of

pure

e, a

dd

2

/

3

cup

of

suga

r an

d m

ix w

ell.

Put

into

con

tain

ers.

Lea

ve h

ead

spac

e, s

eal,

and

fr

eeze

.

Sour

ce

: Mod

ified

fro

m M

ixon

.

7



The latest spiral belt design uses a self-stacking, self-enclosing stainlesssteel belt for compactness, greater reliability, and improved airflow. Thisdesign eliminates the traditional rail system and friction drive. The numberof tiers in the belt stack can be varied to accommodate different capacities.In-feeds and out-feeds can be located to suit most line layouts. This type offreezer is available in a range of models with different belt widths and maybe completely factory assembled or partially assembled in modules for quickinstallation and future portability.

8

Spiral freezers are good systems for products requiring a long freezingtime (generally 10 minutes to 2 hours) and for products that require carefulhandling. Berries can be frozen using this system for IQF products with highquality and efficiency.

10.3.4 Fluidized bed freezer

The fluidized bed freezer is a modification of the air-blast freezer and is usedfor processing small IQF products. Solid food particles ranging in size frompeas to strawberries can be fluidized by forming a bed of particles 25 to 120 mmdeep on a mesh belt (or mesh tray) and then forcing air upward through thebed at a rate sufficient to partially lift or suspend the particles in a mannersomewhat reminiscent of a boiling liquid. If the air used for fluidization isappropriately cooled, freezing can be accomplished at a rapid rate. An airvelocity of at least 114 m/min is necessary to fluidize the particles, and anair temperature of about

−

34

°

C is common.

8

Bed depth depends on the easewith which fluidization can be accomplished, and this in turn depends onthe size, shape, and uniformity of the particles. Freezing time varies withconditions. For strawberries, it takes 9 to 13 minutes to reduce the temper-ature from 21

°

C to

−

18

°

C.

9

The primary product parameter influencing the energy required forfluidization is the size or mass of the product. The limits of use for the processare based on the energy requirements necessary to maintain the fluidizedcondition. Fluidized bed freezing has proven successful for berries becauseof their small sizes. The advantages of fluidized bed freezing compared toconventional air-blast freezing are

8

• More efficient heat transfer and more rapid freezing rate.• Less product dehydration and less frequent defrosting of equipment.• Short freezing time, which is responsible for the small loss of moisture.

A major disadvantage of fluidized bed freezing is that large or nonuni-form products cannot be fluidized at reasonable air velocities.

10.3.5 Liquid immersion and cryogenic freezer

In liquid immersion (usually referred to as direct immersion freezing), theproduct, either packaged or unpackaged, is frozen by immersion in or byspraying with a refrigerant that remains liquid throughout the process.



The common refrigerants used for immersion freezers are liquid nitrogenand carbon dioxide; Freon must be approved for food product contact. Veryrapid freezing is achieved, resulting in superior product quality when therate of ice crystal formation influences quality. The overall process efficiencyis influenced by recovery of expensive refrigerant when the freezing processis complete.

Cryogenic freezing refers to very rapid freezing achieved by exposingfood items, unpackaged or thinly packaged, to an extremely cold freezantundergoing a change of state. Heat removal is accomplished during a changeof state by the freezant, distinguishing this method from liquid immersionfreezing. The most common food-grade cryogenic freezants are boiling nitro-gen and boiling or subliming carbon dioxide.

8

The rate of freezing obtained with cryogenic methods is much fasterthan that obtained with air-blast freezing, but it is only moderately greaterthan that obtained with fluidized bed or liquid immersion freezing. Liquidnitrogen is used in many cryogenic freezers. The product is placed on aconveyor belt and moved into the insulated chamber, where it is cooled withmoderately cold gaseous nitrogen moving countercurrent to the product.Liquid nitrogen is then sprayed or dribbled on the product. After the desiredexposure time, the product passes to an area where it is allowed to equilibrateto the desired final temperature (

−

18

°

C to

−

30

°

C) before it is discharged. Thefinal product temperature is usually no different than that obtained duringconventional methods of freezing.

The advantages of liquid nitrogen freezing are

8

• Dehydration loss from the product is usually much l

es

s than 1%.• Oxygen is excluded during freezing.• Individually frozen pieces of product undergo minimal freezing

damage.• The equipment is simple, suitable for continuous flow operations,

adaptable to various production rates and product sizes, of relativelylow initial cost, and capable of high production rates in a minimalspace.

The disadvantage of liquid nitrogen freezing is its high operating cost,and this is attributable almost entirely to the cost of liquid nitrogen.

In summary, the differences in the costs of forced cold air freezing(air-blast, spiral, and fluidized bed freezing) are likely to be minor. However,when considering the use of cryogenic materials versus cold air, cost differencesbecome significant. The profit motive requires that the least costly method ofdoing a satisfactory job be used. But what is satisfactory or best varies byproduct. For some products, the freezing rate is not critical, such as slicedstrawberries mixed with sugar. Other products may have significant qualityloss when slow freezing is applied. For example, whole strawberries suffertexture damage with excessively slow freezing since they have a high moisturecontent and lack the physical structure to withstand freezing damage.



10.4 Innovation in the freezing process of berries

Several procedures and methods have been evaluated for improving thequality of frozen berries by focusing on reducing drip loss, improving firm-ness, and enriching nutrients. For example, calcium was used to improvethe firmness of frozen berries, and stabilizers, such as starches and gums,have been used to promote freeze/thaw stability.

3

Recently vacuum impreg-nation with cryoprotectants or cryostabilizers and the use of edible coatingson the surface of berries have been investigated as pretreatments for freezing;these are discussed in the following sections.

10.4.1 Vacuum impregnation pretreatment using cryoprotectants or cryostabilizers

Vacuum impregnation is a technology that immerses high porosity foods, suchas some types of fruits and vegetables, in a sugar or salt aqueous solution,applying a vacuum, and then restoring the system to atmospheric pressure. Thecortex, or the surface of the fruit or vegetable, acts as a semipermeable mem-brane, allowing solutes from the solution into the food and moisture from thefood into the solution. In this multiphase food system, both solutes and waterseek equilibrium. When the water activity and concentrations of all componentsequalize, the movement toward equilibrium stops. Vacuum impregnation hasbeen used as a pretreatment step before many complementary processing stages,such as drying, freezing, and canning, to improve quality and save energyduring further processing.

10,11

Cryoprotectant is impregnated into fruit beforefreezing to decrease the amount of freezable water, thus reducing texturalchanges and drip loss during thawing.

12–16

Vacuum impregnation was alsoapplied to impregnate both cryoprotectants (high fructose corn syrup [HFCS]or high methoxyl pectin [HMP]) and minerals (calcium gluconal [CG] and zinclactate [ZL]) into marionberry

15

and strawberries

16

before freezing to improvequality and enrich the nutrient content in the berries. The vacuum impregnationprocess consisted of 15 minutes in a vacuum at 50 mmHg, followed by atmo-spheric pressure restoration for 30 min. The vacuum impregnation pretreatmentincreased the maximum compression force of frozen marionberries 45% to 137%and strawberries 50% to 100%, and reduced drip loss 28% to 48% for marion-berries and 20% to 50% for strawberries, depending on the specific vacuumimpregnation conditions. Calcium provided additional benefits to the texturequality, and zinc improved color stability of frozen berries. It was suggested thatvacuum impregnation pretreatment might be applied for commercial freezingof IQF berries when high quality and enhanced nutritional value are required.

10.4.2 Edible coatings to improve integrity and control drip loss of frozen berries

Edible coatings is a technology of applying a thin layer of edible material to thesurface of a food to protect the food from deterioration or to add other func-tionalities. This technology has been commercially applied to fresh fruits and



vegetables, as well as other types of food for the purpose of food processingand preservation. For fresh fruits and vegetables, edible coatings are used toprotect the produce from deterioration by retarding dehydration, suppressingrespiration, improving textural quality, helping retain volatile flavor com-pounds, and reducing microbial growth.

17

Over the last decade, interest has beenrapidly growing in the development and use of edible coatings to prolong shelflife and improve the quality of fresh, frozen, and formulated food products.

18

Han et al.

19

investigated the use of edible coatings to reduce drip lossand protect the texture of frozen berries by controlling the migration of waterfrom the fruit. A 1% chitosan-based edible coating was applied to the surfaceof strawberries (Totem) and red raspberries (Tullmeen) before freezing. Theberries were then frozen inside an air-blast freezer at

−

23

°

C for 5 hours,packaged in zip-sealed polyethylene bags, and stored in the same freezer upto 6 months. The coating reduced the drip loss to 25% and helped maintainthe textural quality of frozen berries after thawing.

10.5 Ensuring the quality of frozen berries

The chief function of freezing is to preserve food while maintaining its highquality. This is accomplished by reducing product temperature, thereby slow-ing quality deterioration processes. For frozen berries, the major qualities takeninto consideration are flavor, color, nutrients, texture and drip loss after thaw-ing, the loss of surface moisture (dehydration), and potential microbial growth.The following sections cover suggested procedures for ensuring high qualityin the final product. It is important to note that quality control should start atthe beginning of the process and with raw fruit quality itself.

10.5.1 Quality standards of frozen berries

The U.S. Department of Agriculture’s (USDA) Agricultural Marketing Ser-vice has established grade standards as a measure of quality for frozenberries. The USDA provides an inspection service that certifies the qualityof frozen berries on the basis of these U.S. grade standards. The inspectionservice is voluntary and paid for by the users. Many processors, wholesalers,and buyers for food retailers use the USDA grade standards to establishvalues for their products described by grades. Under the program, frozenberries are inspected by highly trained specialists during all phases of prep-aration, processing, and packaging.

Frozen berries are generally ranked in four grades: U.S. Grade A (U.S.Fancy), U.S. Grade B (U.S. Choice), U.S. Grade C (U.S. Standard), and U.S.Grade D (U.S. Substandard).

20–23

U.S. Grade A are berries of similar varietalcharacteristics that possess a practically uniform typical color, a reasonablygood character, and a normal flavor and odor. This highest grade of fruits isthe most flavorful and attractive, and therefore is usually the most expensive.

U.S. Grade B berries are the predominant fruits that are frozen and are ofvery good quality. They are berries of similar varietal characteristics that



possess a reasonably uniform typical color; may possess a fairly good charactertypical of fairly well-ripened to very ripe berries with not more than 30%, byweight, for blackberries and not more than 40%, by weight, for boysenberries,dewberries, loganberries, youngberries, and other similar types that may becrushed; and possess a normal flavor and odor. These berries are only slightlyless perfect than Grade A in color, uniformity, and texture.

U.S. Grade C frozen berries may contain some broken and uneven pieces.While flavor may not be as sweet as in higher grades, these fruits are still goodand wholesome. They are useful where color and texture are not of greatimportance, such as in puddings, jams, and frozen desserts. Grade C fruitsvary more in taste and appearance than the higher grades and they cost less.

U.S. Grade D frozen berries are berries that fail to meet the requirementsof U.S. Grade C. Table 10.3 is a summary of the U.S. standard grades offrozen berries.

10.5.2 Rapid freezing to obtain small regular ice crystal formation

The freezing rate has a significant impact on the quality of frozen berries.Rapid freezing results in a large number of small ice crystals, while slowfreezing allows initially formed ice crystals to grow in size. Rapid freezingallows the product to get through the zone of solute concentration morequickly, thus minimizing concentration effects by decreasing the time con-centrated solutes are in contact with food tissues, colloids, and individualconstituents. Increasing the concentrations of dissolved solids lowers thefreezing point of a solution. As the water freezes, it concentrates the dissolvedsolids and reduces the freezing point of the unfrozen liquid. Lowering thefreezing temperature helps maintain desirable sensory properties by lessen-ing the types of damage that occur during frozen storage. Solute concentra-tion damage can be avoided during the freezing process if the freezing pointis depressed so that no ice is formed. Lowering the freezing point can alsomake the product easier to thaw and prepare, and can create softer texturesdirectly out of the freezer.

3

10.5.3 Prevention of quality deterioration during frozen storage

At subfreezing temperatures, foods are not completely frozen and will con-tinue to deteriorate. Freezing is very destructive to tissue cells or anythingelse containing water because water expands when it freezes. If the storagetemperature is incorrect or there is a temperature fluctuation, physical andchemical reactions can occur to reduce the quality and shorten the shelf lifeof frozen berries.

3

10.5.3.1 Ice crystal size and shape

During frozen storage, ice crystals undergo metamorphic changes. The num-ber of ice crystals is reduced and their average size increases as a result ofthe surface energy between the ice and the unfrozen matrix. Temperature



Tabl

e 10

.3

U.S

. Sta

ndar

ds

for

Gra

des

of

Froz

en B

erri

es

Vari

ety

of b

erry

Des

crip

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Styl

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Gra

de

Ref

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ces

Blu

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lueb

erri

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re p

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m s

ound

, pro

perl

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frui

t of t

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h (g

enus

Vac

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spec

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or v

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ties

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alle

d h

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ries

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n an

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mpe

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, Gra

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(U.S

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, Gra

de

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(U.S

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(U.S

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20

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frui

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stem

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and

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be

pack

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edia

, and

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t te

mpe

ratu

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r pr

eser

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on o

f th

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oduc

t.

Red

ras

pber

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are

red

or

red

dis

h pu

rple

in

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r. B

lack

ra

spbe

rrie

s ar

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ack

in c

olor

.

Gra

de

A (

Fanc

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rad

e B

(U

.S. C

hoic

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rad

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(U

.S. S

ubst

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)

21

Stra

wbe

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str

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s ar

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rope

rly

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sh f

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of

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stra

wbe

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plan

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hey

are

stem

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, pro

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d, a

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rain

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hey

may

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wit

h or

wit

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med

ium

, and

are

the

n fr

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in a

ccor

dan

ce w

ith

good

com

mer

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pra

ctic

es a

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mai

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at

tem

pera

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s ne

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for

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prod

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etai

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imat

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(U

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(U

.S. S

tand

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ubst

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22

Oth

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om p

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and

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the

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boys

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lo

ganb

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sim

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U.S

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A (

Fanc

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Gra

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U.S

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, U

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.S.

Subs

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23

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: Ad

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USD

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20–2

3



fluctuations reduce the size of small crystals more than that of large crystals.During cooling cycles, crystals with larger cross sections are more likely tocapture water molecules that are transferring back to the solid phase. Thecombined effect of product structure, interfaces, and the different moistureconcentrations work together to move water toward the surface of the product.

10.5.3.2 Moisture migration

Temperature gradients within a product during frozen storage may result inmoisture migration. Water will migrate down a temperature gradient becauseof the temperature dependence of water vapor pressure. When there is a voidspace around a product in a package, moisture transfers into this space andaccumulates on the product surface and on the internal package surface.

10.5.3.3 Sublimation

Sublimation occurs as water passes directly from the solid state to the vaporstate, or from frozen food into the atmosphere around the product. Moisturevapor in the atmosphere attempts to reach equilibrium with the foods withina room, as well as with the room itself. The temperature of the freezing coilis always lower than the air in the storage room, thus ice will form andaccumulate on the coil. Sublimation is a principal contributor to the forma-tion of freezer burn on food products. It increases the oxygen contact withthe food surface area, and in turn irreversibly alters color, texture, and flavor.

10.5.3.4 Solute crystallization and pH changeAfter freezing, solutes may be supersaturated in the unfrozen phase. In time,these solutes may crystallize or precipitate and change the relative amountsof solutes and the actual concentration of solutes. Therefore the ionic strengthand pH can change due to changing ratios of buffer components. Thesefactors also affect the stability of other molecules, causing changes in thecharacteristics of molecules in solution.3

10.5.3.5 Freeze/thaw cyclesRepeated freezing and thawing is very damaging to tissue structure (i.e., thetexture of food). Most frozen food distribution systems have measurable tem-perature cycles, but there is great variability in the temperatures of consumers’freezers. Whatever the fluctuation in storage temperature, there will be a lageffect on the food because heat transfer has a finite rate. However, largetemperature variations over long storage times can cause noticeable damage.

It is generally considered that below −12°C, microbial growth stops oris extremely slow. During frozen storage, the product must not be allowedto thaw, as this will allow any surviving microorganisms to grow. Thawingfollowed by refreezing causes ice crystals to grow larger, causing rupture ofthe cell structure and a product with poor texture. To maintain top quality,it is recommended that frozen berries be stored in commercial freezers at −23°or lower immediately after freezing. During transportation and distribution,



berries should be maintained in insulated packages/containers that areequipped with their own refrigeration units. Upon arrival at the retailer, thefruit should be stored and maintained at −18°C. Storing frozen berries attemperatures higher than −18°C increases the deterioration rate and canshorten shelf life. Frozen berries should be packed in tight-fitting, water-and vapor-proof material so that evaporation and sublimation cannot occur.3

10.5.4 Packages for limiting moisture loss and gas transfer

Frozen berries must be packaged properly to protect their flavor, color,moisture content, and nutritive value from the dry environment inside thefreezer. In general, packaging materials used for frozen berries should meetthe following requirements:

• Moisture and vapor resistant to prevent the transfer of moisture andair in and out of the package.

• Durable and leak-proof at low temperatures; also, it should not becomebrittle and crack at low temperatures.

• Prevent absorption of off-flavors or odors from the freezer.• Easy to seal and label.

The permeability characteristics of packaging materials govern the rateof weight loss during frozen storage. Suggested packaging materials forfrozen berries include rigid containers made of plastics, and flexible pack-aging materials, including plastic bags, heavy aluminum foil, plastic film,polyethylene, and laminated paper.

Moisture barrier polymer wraps and bags, waxed cartons, or over-wrapped trays are commonly used for packaging frozen berries. Polyethyl-ene is widely used for most IQF berries because it has high abuse resistanceat temperatures down to −50°C and gives the best moisture barrier propertiesof the readily available packaging materials. Polyethylene-coated chipboardis used where delicate berries are block frozen in their containers. Polyeth-ylene-lined multilayer paper bags may be used as larger containers. Waxedcartons are suitable for fragile fruit such as raspberries, and bags can be usedfor more robust fruit such as blueberries. Paper boxes can be used withplastic bags as liners, as they are easy to stack and help save space.

10.6 Applications of frozen berriesThe market for frozen berries is huge and growing because of increasedconsumer awareness of the health benefits of berries and their unique colors,flavors, and tastes. Frozen berries are utilized in many different ways. Someexamples of their applications include

• End products for direct consumer use.• Beverages, such as smoothies, milk shakes, malted drinks, and yogurt

drinks.• Jams, jellies, preserves, and dried fruits.



• Dairy products such as ice cream, yogurt, frozen novelties, sherbets,fruit bars, and puddings.

• Bakery goods, including berry bread, cakes, tarts, muffins, and piefillings.

Table 10.4 provides examples of applications of some frozen berries basedon packing types.

In the past 10 years, studies have identified an array of components inberries as nutraceutical ingredients. It has been noted that the combinationof phytochemicals (naturally occurring chemicals from plants) in berriesmakes them especially nutritious, with benefits that no individual phy-tochemical dietary supplement can even come close to providing.24

The use of berries in dairy products is increasing. One example is a newgeneration of flavored cottage cheeses.24 With cottage cheese, which inher-ently has texture due to the curd particles, fruit is desirable in both blendedand fruit-on-the-bottom varieties. Fruit integrity is most important inside-by-side fruited cottage cheese, as in yogurts.

The fruit form used in various dairy products varies based on the man-ufacturer’s goal for the product. For smoothies and gelato, low particulatefruit varieties are usually used. However, for ice creams, fruit with particu-lates along with identifiable berries is added.

For premium dairy products such as refrigerated desserts, or whereverfruit identity is of utmost importance, IQF berries are appropriate. Thesefruits typically contain no sugar or preservatives, but some processors offerIQF fruits infused with a sugar solution to prevent them from freezing solidin frozen applications. Either form separates easily when added to a mix,enabling even dispersion. Frozen sweetened and unsweetened berries arealso available; however, as the product thaws, traditionally frozen fruit losesits integrity, often breaking up.

Table 10.4 Examples of Applications of Some Frozen Berries Based on Packing Types

Type of frozen berry Example of applications

Individually quick frozen

Ice cream, yogurt, and toppings, cereals, juice, freeze-dried products, jams, preserves, and smoothies

Food service and bars mixesRetail grocery chains

Sugar packed (sliced or whole)

Dairy products, mainly ice creamJams and preserves

Puree Food serviceProduction of jams, jellies, ice cream, and yogurtJuice manufacturing and brewery specialty products

Other Juice stock, juice stock used for bar mixes, juice stock used for smoothies, and canned strawberries sold in retail grocery chains

Drum packs used for syrups and jams



Frozen berries packed in thick and sweetened syrup are best used as piefillings. Many consumers perceive pie filling as highly processed, and as a result,it is not typically used in dairy products, except in sundae-type novelty cups.

10.7 ConclusionFreezing is the most common processing and preservation technologyapplied to berries because of its power to reduce chemical and biologicalreactions in foods, preservation of nutrients and important quality attributes,and relatively low operating costs. Different freezing equipment—air-blast,spiral belt, fluidized bed, and liquid immersion—and packing methods—liq-uid or dried, sweetened or unsweetened, or IQF—may be applied based onthe requirements of final product quality, end application, and operatingcosts. The important quality controls in the freezing process include initialproduct condition (maturity, sanitation condition, etc.), freezing rate (rapidor slow freezing), packing methods before freezing (with or without sugar,dry or liquid sweetener), packaging materials, and storage conditions. Whenapplied appropriately, high quality and longer shelf life of frozen berries canbe obtained. Frozen berries have wide applications as end-use products oras ingredients in other manufactured products because of their importantnutritive and health benefits, as well as their colors, flavors, and tastes. Inaddition, the freezing process is a significant step in other food processes,such as dehydration and juice manufacture.

References1. Desrosier, N. and Tressler, D., Fundamentals of Food Freezing, Avi Publishing,

Westport, CT, 1977.2. Mogons, J., The Quality of Frozen Foods, Academic Press, London, 1984.3. Kobs, L., Designing frozen foods, Food Product Design, January, 27, 1997.4. Krese, C. and Jacobs, M., FDA rules frozen fruits and vegetables have equiv-

alent, if not better, nutrient profile than fresh product, American Frozen FoodsInstitute, http://www.healthyfood.org/sub/news_03.25.98.html, 1998.

5. American Frozen Food Institute, 2003 Frozen Food Pack Statistics Book, AmericanFrozen Food Institute, McLean, VA, 2004.

6. Brief instructions for freezing fruit, Electronic Publication HE-246, NorthCarolina Cooperative Extension Service, North Carolina State University,Raleigh, NC, http://www.ces.ncsu.edu/depts/fcs/food/pubs/fcs246.pdf, 1993.

7. Mixon, M.J., Freezing fruits and berries, Publication 1430, Mississippi StateUniversity Extension Service, Mississippi State, MS, 2002.

8. Freezing methods and quality loss at freezing temperatures, III UNISWORKFood Safety Programme, United Nations Industrial Development Organization(UNIDO), Vienna International Centre, Vienna, Austria, http://www.unido.org/file-storage/download/?file_id=32111, 2004.

9. Fennema, O., Karel, M., and Lund, D., Principles of Food Science, Part 2: PhysicalPrinciples of Food Preservation, Marcel Dekker, New York, 1975.

10. Torreggiani, D., Osmotic dehydration in fruit and vegetable processing, FoodRes. Int., 26, 59, 1993.



11. Torreggiani, D., Forni, E., Maestrelli, A., Bertolo, G., and Genna A., Modifi-cation of glass transition temperature by osmotic dehydration and color sta-bility of strawberry during frozen storage, in Proceedings of the 19th Congressof Refrigeration, Vol. 1, IIF-IIR, The Hague, 1995, p. 315.

12. Martinez-Monzo, J., Martinez-Navarrete, N., Chiralt, A., and Fito, P., Mechanicaland structural change in apple (var. Granny Smith) due to vacuum impreg-nation with cryoprotectants, J. Food Sci., 63, 499, 1998.

13. Sormani, A., Maffi, D., Bertolo, G., and Torreggiani, D., Textural and structuralchanges of dehydrofreeze-thawed strawberry slices: effects of different dehy-dration pretreatments, Int. J. Food Sci. Technol., 5, 479, 1999.

14. Torreggiani, D. and Bertolo, G., Osmotic pretreatments in fruit processing:chemical, physical and structural effects, J. Food Eng., 49, 247, 2001.

15. Xie, J. and Zhao, Y., Improvement of quality and nutritional value in frozenmarionberry by vacuum impregnation, J. Hort. Sci. Biotechnol., 78, 248, 2003.

16. Xie, J. and Zhao, Y., Vacuum impregnation with cryoprotectants and nutra-ceuticals to improve quality and enhance nutritional value of frozen straw-berries (Totem), J. Food Prot. Preserv., 28, 117, 2004.

17. Debeaufort, F., Quezada-Gallo, J.A., and Voilley, A., Edible films and coatings:tomorrow’s packagings: a review, Crit. Rev. Food Sci., 38, 299, 1998.

18. Diab, T., Biliaderis, C.G., Gerasopoulos, D., and Sfakiotakis, E., Physicochem-ical properties and application of pullulan edible films and coatings in fruitspreservation, J. Sci. Food Agric., 81, 988, 2001.

19. Han, C., Zhao, Y., Leonard, S.W., and Traber, M.G., Edible coatings to improvestorability and enhance nutritional value of fresh and frozen berries, PostharvestBiol. Technol., 33, 67, 2004.

20. USDA, United States standards for grades of frozen blueberries, U.S. Depart-ment of Agriculture, Washington, DC, http://www.ams.usda.gov/standards/fzblberr.pdf, 1957.

21. USDA, United States standards for grades of frozen raspberries, U.S. Departmentof Agriculture, Washington, DC, http://www.ams.usda.gov/standards/fzraspbe.pdf, 1957.

22. USDA, United States standards for grades of frozen strawberries, U.S.Department of Agriculture, Washington, DC, http://www.ams.usda.gov/standards/fzstrawb.pdf, 1958.

23. USDA, United States standards for grades of frozen berries, U.S. Departmentof Agriculture, Washington, DC, http://www.ams.usda.gov/standards/berries.pdf, 1967.

24. Berry, D., The latest and greatest on cherries and berries—the use of fruit indairy products, Dairy Foods, November, 2001.



313

chapter 11

Dehydration of berries


Contents

11.1 Introduction ............................................................................................... 31411.2 High-temperature dehydration .............................................................. 315

11.2.1 Water activity ................................................................................ 31511.2.2 Heat transfer ................................................................................. 31711.2.3 Mass transfer................................................................................. 31711.2.4 Drying phenomena ...................................................................... 318

11.3 Conventional methods for dehydrating berries .................................. 31911.3.1 Drying methods and equipment ............................................... 319

11.3.1.1 Sun drying ...................................................................... 31911.3.1.2 Hot air drying ................................................................ 32011.3.1.3 Drum and spray drying ............................................... 32111.3.1.4 Vacuum drying .............................................................. 32111.3.1.5 Freeze-drying ................................................................. 322

11.3.2 The drying line ............................................................................. 32211.3.3 Further processing of dried berries........................................... 326

11.4 Innovation in fruit dehydration ............................................................. 32711.4.1 Osmotic dehydration................................................................... 32811.4.2 Microwave and combined

microwave/vacuum processes .................................................. 32911.4.3 Vacuum infusion or impregnation process.............................. 329

11.5 Critical quality and safety factors: Control of qualityand nutritional losses during drying .................................................... 33011.5.1 Quality factors .............................................................................. 33011.5.2 Nutritional and safety factors .................................................... 33111.5.3 Packaging....................................................................................... 331



11.6 Applications of dried berry fruit............................................................ 33211.6.1 Snack foods ................................................................................... 33211.6.2 Breakfast cereals ........................................................................... 33211.6.3 Formulated foods ......................................................................... 332

11.7 Conclusion.................................................................................................. 333References ........................................................................................................... 333

11.1 Introduction

Dehydration is an ancient food preservation method. The principle of fooddehydration is based on the removal of water from food materials, using thedriving force of heat transfer for water evaporation or sublimation. In allcases, water is removed with the purpose of decreasing the water activityof food to produce a longer shelf life.

1–3

High-temperature dehydration includes two different unit operations:heat transfer from a heat source to the food material, and mass transfer fromthe food material to the surrounding media. When high temperature isinvolved, evaporation of water occurs at normal pressure, while infreeze-drying, temperature and pressure are low and sublimation of wateris the result of the process.

3

Dehydration of berries must consider the effect of temperature on allfactors that determine the nature of the fruit, such as phenol content, solublefiber content, vitamins, etc. The use of high temperatures can produce adeleterious effect in the product instead of maintaining the qualities forwhich these products are especially appreciated.

Dehydration is not the principal preservation or processing method usedin berries, but it is one of the more suitable alternatives to maintain specificfunctional components such as dietary fiber, pigment, and low molecularweight carbohydrates. Dehydration should be used with special care inberries with high phenolics and sugar content in order to avoid chemicalchanges that may lead to the loss of these important functional components.Dehydration should be carried out at low temperatures to produce a low-ratewater removal, thus avoiding hardening and sugar crystallization. One alter-native to high-temperature air dehydration is the use of osmotic dehydrationor sugar infusion to produce the same reduction in water activity.

Another dehydration method normally used for berries is spray drying,which applies a berry powder starting with a concentrated berry juice ofabout 50

°

Brix. The dried products are suitable for extracting pigments andother functional compounds.

When the term berry fruit is used, a large number of different botanicalfruits are included, but there are a few that have real economic importance,including grapes, blueberries, raspberries, strawberries, boysenberries, andcranberries. Most of these species have shown relevant functional activitiesrelated to scavenging free radicals, antioxidation, and antiseptic behavior toseveral microorganisms.


Chapter 11: Dehydration of berries 315

The value of these species in health enhancement has been noted in thelast 10 years and preservation of these qualities is necessary in any processingmethod. The natural fresh condition represents the baseline to which anyprocessed material should be compared, but concentration of the functionalcompounds present in the fruit is a requirement for the industrial productionof high-value functional foods.

Today, dehydration is a common method used to preserve berries. Thischapter discusses important dehydration processes used for berries, as wellas control of product quality and safety.

11.2 High-temperature dehydration

High-temperature dehydration is a combination of two unit operations act-ing simultaneously: heat transfer and water mass transfer. Heat is normallyproduced by a combustion source; an indirect heat exchanger transferringenergy to an air stream that conducts it to water in the product. Waterevaporates and the water vapor produced is then removed from the productsurface and out of the drier by the air stream. The heat transferred to theproduct and the water transferred from the product to the air stream areaffected by the air, water content, relative humidity, and dry bulb and wetbulb temperatures.

1,3,4

The dehydration process, in fact, is very complex.

11.2.1 Water activity

Water activity (

a

w

), not the total amount of water in the product, determinesthe available water for microbial growth, enzymatic activity, and chemicalreactions that change product quality and affect the nutritional value,appearance, and global acceptance of food products. Most bacteria will notgrow at water activity levels less than 0.80, while most molds and yeastswill not grow at water activity levels of less than 0.70. If water activity iscontrolled, it is possible to control the potential sources of spoilage. Dehy-dration is an effective way to reduce water activity, thus it is an effectiveway to control microorganisms that can cause damage to food products.Figure 11.1 shows the effect of water activity reduction on fruit leather. Iffruit leather is in the presence of a saturated water media, such as apotato-dextrose agar, water activity increases to greater than 0.75, a conditionin which molds will develop. If fruit leather is placed in an empty Petri dishat normal relative humidity, the product does not show any mold develop-ment for up to 6 months. This shows that at normal environment humiditylevels, reduced water activity in the product permits its preservation.

All food products have water in the form of bound water. While theamount of water is decreasing in the product matrix, the bound water energyis increasing, thus the amount of free water is reduced. Free water is the activewater available for microorganism growth and reactions, while bound waterstrongly links to hydroxyl groups of polysaccharides, carbonyl and aminogroups in proteins, and other polar groups in food product components.



Control of nonenzymatic reactions, such as Maillard reactions, could beeffective when water activity is reduced to less than 0.4, since most chemicalreactions develop with water activity levels of 0.6 to 0.7. Enzymatic reactionsnormally occur when water activity is 0.6 or greater, but they slow downwhen water activity is less than 0.6. In berries, enzymatic and oxidativereactions related to phenolic compounds should be controlled, since thosecompounds determine the antioxidant activity of fruits, one of the mostinteresting functional properties of berries.

Water activity is defined as

a

w

=

l

w

x

w

=

p

/

p

0

(11.1)

where

l

w

is the activity coefficient of water,

x

w

is the mole fraction of water in the aqueous fraction,

p

is the partial pressure of water in the material, and

p

0

is the partial pressure of pure water at the same temperature.

Defined in this way, water activity is equal to the equilibrium relativehumidity (ERH) divided by 100, expressed as a fraction. This relation permitscontrol of the storing process for low-moisture products, which has to bedone with use of special packaging materials that permit control of theexchange of moisture between the environment and the product. The ideais to maintain the inside environment at the ERH equivalent to the product’swater activity. Today, a number of materials have been developed to maintainconditions for low-moisture food materials.

Most raw berries have water activity levels greater than 0.95, with mois-ture contents of greater than 88%. A water activity level less than 0.70 fordehydrated berries permits their preservation. However, texture is modified

Figure 11.1

Effect of water activity of fruit leather pieces in the presence of (a) excesswater and at (b) environmental humidity.

a b



by the dehydration process and the reduction of water activity, thus dehy-drated berries have a different character compared to the original raw mate-rial, including structural transformations, enzymatic changes, nonenzymaticbrowning, and oxidation. All these deleterious changes depend on the wateractivity, temperature, and extent of water plasticization.

5

The quality of dehydrated berries depends on the process, the rate ofwater removal, the pretreatments applied, the condition of the fruit (whole,cut, mashed), and the packaging material used. Storage conditions of driedfruits can also have an impact on final product quality.

11.2.2 Heat transfer

Heat transfer is produced as a result of a temperature gradient between theair stream and the product surface. The evaporation rate of water is propor-tionally related to the heat transfer to the product surface. Water evaporationmay occur on the surface or in the interior tissues, depending on the amountof free water present in the tissue and the heat transfer rate occurring in theprocess. Conditions in the air stream are very important for the drying rate.

Energy can be supplied by the sun or mechanically produced from acombustion source or from a wave emission unit. Heat provides energy towater for evaporation. The water vapor pressure is increased by one of theheating mechanisms and water is then vaporized or sublimated from thesurface of the fruit or from the internal tissues. This water movement occursbased on mass transfer phenomena.

3

Heat transfer to the drying material in hot air dehydration occurs bytwo mechanisms: convection, in which heat is transported from an air streamflowing over or through the material, and conduction, in which heat ismoving inside the product. Heat transfer from the air stream to the productsurface occurs because of the temperature gradient and is controlled by aheat transfer coefficient that depends mainly on air speed and flow, whileheat transfer inside the product depends on the fruit type, water content,and temperature gradient inside the fruit.

4

The best way to optimize the heat transfer is to control the airflow; the moreturbulent the airflow, the higher the heat transfer coefficient, and thus the fasterthe heat transfer. Normally heat transfer is controlled by fruit internal resistance,but in a laminar airflow, heat transfer can be lower due to a lower heat transfercoefficient of the product surface. Therefore the heat transfer process can becontrolled in a well-designed drier by controlling the air temperature, the airflowspeed and the nature of the flow, the way the air contacts the product, and theresidence time of the product in the drier, since the temperature on the productsurface is part of the driving force in the heating process.

11.2.3 Mass transfer

Mass transfer in dehydration occurs by two phenomena: capillary flow dueto gradients of capillary suction pressure and diffusion in the liquid or vaporphase. Convection occurs principally between the product surface and air



with a different partial vapor pressure than the product. During the dryingprocess, water moves from the center of the product to the surface based ondiffusion. When water activity is high, that is, the amount of free water islarge, water moves inside the product by capillarity. During dehydration,the amount of free water is lower, the capillaries close because of tissueshrinkage, and thus diffusion occurs in the liquid phase. When there is nomore free water in the tissue, the dehydration plane is inside the tissue, butnot on the surface; hence, water diffusion through the tissue to the surfaceis in the vapor phase. Mass transfer is one of the important factors in dehy-dration efficiency, directly impacting the texture and structure of the productto be dried.

1,2

The nature of fruit tissue is determined by fruit ripeness, size, the waxcontent of the cuticle, and the amount of water and soluble solids. These areall important factors influencing water mass transfer from internal tissue tothe surface and from the surface to the air stream surrounding the fruit.Berries to be processed or preserved by dehydration normally present anopen structure, but the cuticle is a very strong barrier to water removal,especially when a thick layer of wax covers it. This is especially true forblueberries and black currants. Epicuticular wax can be treated with a dyesolution, but cracks in the wax permit water transfer to the surface andevaporation from there.

6

To summarize, there are several water-movement mechanisms in struc-tured materials. These include liquid water moving by capillary flow, liquiddiffusion, diffusion at the surface water layer adsorbed in solid tissue, watervapor diffusion, and water vapor flow caused by pressure differences invacuum drying.

1,4

11.2.4 Drying phenomena

When berries are placed in a drier, the process does not follow a linealbehavior. Water is removed in different stages depending on the variety ofthe fruit, its structure, the presence of seeds, and the nature of the skin andepicuticular waxes. In a homogeneous material model with no volumechange during drying, three stages are recognized. When the surface con-tains a significant amount of free water, after a very short period in whichthe tissue is warmed, the drying rate is constant. This stage remains untilthe water content reaches a point called the critical moisture content of thematerial. After this point, the drying rate decreases following a logarithmicfunction, becoming virtually zero after several hours.

The initial drying process is externally controlled, as mentioned byCrapiste and Rotstein.

4

The rate-controlling step for evaporation is the dif-fusion of water vapor through the thin layer of the air-surface interface. Itis assumed that at the beginning, the free water permits the process to beconducted at the wet bulb temperature on the surface. However, berriessuffer permanent deformation or shrinkage during the drying process, thusthere is no free water on the product surface controlling the drying rate.



This produces only one stage after the warm-up period. With the exceptionof freeze-drying, where the total volume of cells and tissue remains almostconstant throughout the drying process, all other drying methods involvingheat treatments have a very heterogeneous drying process, where the controlof water removal is very important to control shrinkage and other damageproduced by the process. Drying conditions and fruit transformation greatlyaffect product quality. Berries have very variable conditions in sugar andacid content, skin or cuticle thickness, seed presence, and water content.These variables determine the drying behavior of the fruit and thus thequality of the dried product.

For the dehydration of berries, some pretreatments are used to enhancethe drying rate, thus allowing shorter processing times for better productquality, including texture and color, and less damage to valued compounds(vitamins, phenols, etc.). Some of these pretreatments include mechanicalor chemical skin perforation and partial water removal with osmotic solu-tions. All these pretreatments produce a shorter drying time with a higherdrying rate.

5,7

11.3 Conventional methods for dehydrating berries

Conventional methods for the dehydration of berries include sun drying andmechanical dehydrators that use a heated air stream. The fruit is placed ondifferent still or moving devices, where hot air passes over the surface of thefruit or through the fruit in a concurrent or countercurrent direction, depend-ing on the structure and nature of the fruit to be dried. Conventional methodsremove moisture from the product to the air driven by the moisture differ-ence between the product surface and the air, and the temperature differencebetween the surface and the inner tissue of the product.

11.3.1 Drying methods and equipment

In addition to classic sun drying, there are several different types of equip-ment used for fruit dehydration, including hot air drying, drum or spraydrying to obtain fruit powders, microwave and vacuum drying, andfreeze-drying. In this section, some of the general principles of these methodsand equipment are discussed.

11.3.1.1 Sun drying

Sun drying is the classic method used in drying fruits, including grapes,prunes, apricots, peaches, and some berries. However, most industrial dehy-dration occurs under controlled conditions in mechanical driers.

In sun drying, the amount of sunlight, the humidity, and movement ofthe air mass around the product determine the drying rate. Sun drying cantake many days. During the drying period, changes in fruit color and flavorcan occur due to chemical and biochemical reactions, especially in the first2 or 3 days. Since water moves very slowly inside fruit tissues, one of the



advantages of sun drying is that it produces a uniform texture and flavor fromthe inner tissue to the surface of the fruit. After sun drying, the fruit has to befurther processed, including increasing the water content and cleaning thefruit to eliminate all dust materials and other biological contaminants.

Sun drying is a process that cannot be well controlled with respect towater removal efficiency, temperature, air relative humidity, and convectioncoefficients, since all these factors are dependent on the geographic locationwhere the drying occurs. Berries normally grow in temperate or cold weatherzones, which makes the sun drying process difficult. Sun drying requires alow relative humidity, low dew point, and long sunny days. Another prob-lem in sun drying of berries is the nature of the cuticle covering the fruit,especially in cranberries, blueberries, and currants, where a thick wax layerexists as a barrier to water evaporation.

11.3.1.2 Hot air drying

Hot air drying is one of the most common drying methods for food products,including fruits, vegetables, pasta, coffee, and aromatic and medicinal herbs.Dehydration is carried out in a mechanical device where food materials maybe either static or moving and hot air is conducted in different directionsdepending on the product nature. This is the most used system for dehy-dration of berries because the process can be well controlled, producing highquality products. Variables to be controlled include the feeding rate, airvelocity, air humidity inside the apparatus, air recirculation conditions, andfinal moisture content in the product.

According to Crapiste and Rotstein,

4

the selection of a drier for a givenfood depends on the heat source, the type of drying equipment, transporta-tion of the product, the feed nature and state, operating conditions, andproduct residence time. Some of the suitable driers for berries include traycabinet, tunnel type, belt conveyor, and fluidized bed driers. Small wholeberries or cut berries can be processed in any of these types of driers.

Most of hot air driers use product movement to some extent; however,the product can also be completely still during the drying process. Batch-typedriers require some homogenization process, since not all the areas insidethe drier have the same efficiency, thus the final moisture content of theproduct can vary greatly from one area of the dryer to another. Therefore,at the end of process all the products are mixed together and homogenizedin a bin cabinet drier with a high-volume, low-speed hot air current. Thisproduces a product with a uniform moisture content. This procedure issometimes is applied to products dried in a continuous drier to ensureproduct uniformity.

In continuous driers, there are many different ways to move the productfor continuity of the process. For example, trays may enter in the lower partof the drier and exit in the upper part. After a certain period of time, eachtray moves up one level in the dryer. Other driers have a continuous beltthat transports the product from a lower temperature, higher humidity zoneto a higher temperature, lower humidity zone. Wet product with a low



temperature and high humidity will have a low dehydration rate, while thewithdrawing (dried) product will have a high temperature and low humid-ity; thus the drying rate can be controlled. Air movement in these driers mayflow parallel to the product flow or countercurrent to it. The direction ofairflow can also be horizontal or vertical to the direction of product flow.Airflow is a very important factor in the dehydration rate, not only the airspeed, but also the way the air contacts the product.

One very important variable in hot air dehydration is the loading of thetrays or feeding in a continuous system. The relationship between weightand surface area is an important factor in the efficiency of the drying process.This relationship depends on the nature of the fruit to be processed, its sizeand form, potential drying rate, and the geometry of the system.

11.3.1.3 Drum and spray drying

All the systems discussed previously consider the use of whole or cut fruit;however, fruit powders have become important products. Dried fruit pow-ders are usually produced using drum or spray driers, where the materialsto be dried are a concentrated fruit pulp or concentrated fruit juice. Drumdriers are heated internally by steam and the fruit pulp or slurry is fed evenlyinto the drum. The critical factor in this process is the feeding rate, sincecontact between the pulp or slurry and the hot drum surface has to be asshort as possible to avoid heat damage, especially chemical and bioactivedegradation.

Spray drying, on other hand, usually uses clarified concentrated juice,although cloudy juice can also be used. Spray drying consists of atomizationof fruit juice into small drops that are conducted against a hot air currentinside of a conical drum, where water is evaporated and dried powder fallsto the bottom and is collected. For products containing large amounts ofsugar, spray drying has to be carried out with the help of coadjuvants inorder to avoid problems with stickiness and to improve the drying rate. Thissystem uses very high temperatures and has high drying rates. Control ofthe air temperature and the speed of juice feeding are very critical in thissystem. Also, the amount of coadjuvant should be carefully determined foreach product. Berries such as raspberries, blackberries, and strawberries aresuitable for this process, producing high-quality dried powders that can beused in the manufacture of different formulated products as natural func-tional ingredients.

11.3.1.4 Vacuum drying

All the methods presented include the physical transportation of heat byone of two mechanisms: convection, a transport method that applies to gasesor liquids, and conduction, molecular transport that applies to liquids, gases,and mainly solids. Convection requires mass to permit heat transfer andcannot operate under vacuum conditions. There are only two ways to pro-duce heat transfer in a vacuum: (1) by conduction, which has the problemthat the transference inside of fruit will be too small compared to that



occurring from the heat source to the fruit; and (2) by radiation. Because ofthis, vacuum drying has been developed mainly after the use of microwavedrying.

In the last 10 to 15 years, microwave/vacuum dehydration has devel-oped very quickly. Today there are several companies manufacturing driersusing this technology at a very affordable cost. Although this system is moreexpensive that other drying methods, the quality of the products is highenough to compensate for the cost. In this system, products are dried underlow temperature with very little damage to their chemical and bioactiveconstituents. Berries are very well processed by this method, preserving allthe principal quality attributes that make the product highly desirable.

11.3.1.5 Freeze-drying

One unique method of drying is freeze-drying, a combined method that usesfreezing and then sublimation of water at very low pressures and tempera-tures. A comparison of freeze-drying with other drying methods is shownin Table 11.1.

In freeze-drying, fruit—whole, cut, or pulp—is frozen at less than 35

°

Cand then heated at low temperature to produce ice sublimation at a very lowpressure, around 0.25 inch of mercury. This low pressure permits sublimationof ice at a very low temperature, a condition where fruit quality is well main-tained. The cost of this drying system is higher than other dehydration meth-ods and thus it is mainly used for products with high quality standards,including berries. Table 11.2 compares the different drying methods.

11.3.2 The drying line

Figure 11.2 shows a general flow diagram for berry dehydration. Not all theunit operations that appear in the diagram are included in the processing ofall types of berries, but most of them are.

2

As in all food processing, the most important control for productquality is the raw material itself: its quality, ripeness, variety, agriculturaland postharvest management, etc. Today, most of the raw materials comefrom agricultural production, but there are several types of fruits that comefrom natural production and collection. The latter, called forest fruits, arevery important because of their organic nature, and thus are usually mar-keted as fresh fruits, but they are also important as high-quality processedingredients for some formulated foods, including yogurt, ice cream, andbreakfast cereal.

Raw materials used in the dehydration process can be fresh or frozen.Normally the water content of raw berries is about 90%, with a wateractivity greater than 0.95%. Hot air dehydration can reduce the moisturelevel to 12% to 18%, with a water activity of about 0.5 to 0.6. This type ofproduct can used directly as a snack or as an ingredient in other processedfoods.



Tabl

e 11

.1

Qua

lity

Los

ses

Prod

uced

by

Diff

eren

t D

ryin

g M

etho

ds

in S

aska

toon

Ber

ries

(

Am

elan

chie

r al

nifo

lia

Nut

t.)

Dry

ing

met

hod

Vari

ety

Ph

enol

ics

(%)

An

thoc

yan

in(%

)R

edu

cin

gp

ower

(%

)

DP

PH

(1,

1-d

iph

enyl

-2-

pic

rylh

ydra

zyl)

rad

ical

sca

ven

gin

g (%

)

AB

TS

(2,2

azi

nob

is(3

-eth

ylbe

nzo

thia

zolin

e-6-

sulf

onic

acid

) ra

dic

al s

cave

ngi

ng

(%)

Froz

en f

ruit

Thi

esse

n10

010

010

010

010

0Sm

oky

100

100

100

100

100

Free

ze-d

ryin

gT

hies

sen

6768

5059

57Sm

oky

9077

7391

79V

acuu

m

mic

row

ave

Thi

esse

n48

5034

3635

Smok

y64

4745

4643

Com

bina

tion

d

ryin

gT

hies

sen

4438

3230

29Sm

oky

5737

4638

30A

ir d

ryin

gT

hies

sen

3417

3126

24Sm

oky

4312

3726

25

Ad

apte

d f

rom

Kw

ok e

t al

.

20



Tabl

e 11

.2

Com

pari

son

of D

iffer

ent

Dry

ing

Met

hod

s

Dry

ing

met

hod

Com

ple

xity

a

Adv

anta

ges

Dis

adva

nta

ges

Inve

stm

ent

Ap

plic

atio

ns

Sun

dry

ing

Ver

y si

mpl

eG

ener

al a

pplic

atio

nD

epen

den

t on

zon

es a

nd

wea

ther

Low

Lim

ited

to

firm

fru

it

like

blue

berr

yH

ot a

ir, b

atch

Sim

ple

Wel

l kno

wn

Non

-hig

h-qu

alit

y pr

oduc

tsL

ow/

med

ium

All

berr

ies

Hot

air

, co

ntin

uous

Sim

ple/

com

plex

Wel

l kno

wn

Non

-hig

h-qu

alit

y pr

oduc

tsM

ediu

mFi

rmer

ber

ries

Dru

m d

ryin

gSi

mpl

eG

ood

for n

onse

nsit

ive

pow

der

Med

ium

mic

robi

olog

ical

qu

alit

yL

ow/

med

ium

Ber

ry f

ruit

pow

der

Spra

y d

ryin

gSi

mpl

e/co

mpl

exG

ood

for

sen

siti

ve

pow

der

Hig

h op

erat

ing

cost

sM

ediu

m/

high

Ber

ry f

ruit

pow

der

Vac

uum

dry

ing

Com

plex

For

sens

itiv

e pr

oduc

tsC

ost

Hig

hA

ll be

rrie

sFr

eeze

-dry

ing

Sim

ple

For

very

sen

siti

ve

prod

ucts

Cos

tH

igh

All

berr

ies

a

Sim

ple:

eas

y to

ach

ieve

, eas

y to

lea

rn t

he t

echn

olog

y , e

asy

to m

anag

e th

e pr

oces

s; S

impl

e/co

mpl

ex: r

equi

res

som

e ex

pert

ise,

tec

hnol

ogy

know

led

ge;

Com

plex

: req

uire

s te

chno

logy

kno

wle

dge

to

oper

ate

the

equi

pmen

t, so

me

basi

cs in

the

rmod

ynam

ics.



After grading, washing, and inspecting, raw materials may be subjectedto some pretreatment for the purpose of enhancing the drying rate or finalproduct quality. The pretreatment step can be done by using mechanical(physical), chemical, or thermal methods.

Mechanical treatments include cutting the fruits into small pieces orperforating the skin of the fruit over 20% to 30% of the surface area.

5

Chem-ical treatments include dipping fruits in a high-temperature chemical solu-tion, such as sodium hydroxide or ethyl oleate in boiling water. Most of thesetreatments significantly affect the acceptability of the product. It has beendemonstrated that a high-temperature treatment at 100

°

C for a short time ismore acceptable than a lower temperature of 20

°

C for a longer time, sincethe shorter the treatment time, the better the quality of the final product.

5

Low-temperature thermal treatment has been used in blueberries. Fruits areindividually quick frozen and stored at 40

°

C until use. Fruits are then thawedat 4

°

C for at least 5 hours; it is during this time that some damage can occur. Thisdamage increases the drying rate due to enhanced mass transfer. Since there

Figure 11.2

General flow diagram for dehydration of berries using hot air.

Storing rawmaterial

Feeding toprocessing

line

Stemmingwhen is

necessary

Grading

Washing

Dewatering Inspecting

Slicing,perforating or

skin alcalitreatment

Drying

Binhomogenizing

Inspecting

Cartonfilling

Warehousingand

shipping



is no further treatment after thawing, the qualities of the blueberries are mostlypreserved. However, this method may add extra costs to the processing.

After pretreatment, the fruit is placed on trays, on a belt conveyor, or ina fluidized bed system for processing in a tunnel or cabinet drier. Becauseof the resistance of the waxy skin to mass transfer in some berries, the amountof fruit material in a given surface area (mass density of fruit materials)inside the drier has to be well controlled to ensure short processing times.

Because of the relatively slow removal of water from berries, the airstream is normally countercurrent to the product or through the productbed. The heating process should be carefully controlled to avoid hardeningas the result of sugar migration from the inner tissue to the surface. If casehardening occurs, the drying process becomes very slow.

The size of the fruit pieces and the density of the fruit material insidethe drier are also very important to obtain uniformly dried material. How-ever, since the geometry of the drier is not always perfect for homogeneousdrying, there are always some variations in the moisture content of the finalproduct.

2

By cutting fruits into small pieces, this variation can be controlledmore easily. Also, products can be homogenized after the primary dryingprocess. After the first drying step, the moisture content is usually loweredto about 12% to 18%; after the homogenizing step, the moisture content canbe lowered up to 5%.

After the product has been homogenized it should be inspected toremove any defective product. Inspected products are then sent to a pack-aging line or are kept in bins for further processing. If the products areimmediately delivered to other processors, they are dried to a moisturecontent not less than 10%, while products that are kept for storage in theplant should be processed to a moisture content of about 5%. The driedproducts are then stored in bulk in a low-humidity environment.

11.3.3 Further processing of dried berries

Most dried fruits are processed according to the uses and quality specifica-tions of clients. Processing consists of several potential operations, includingfurther cleaning, grading, washing, and moisture adjustment. Figure 11.3shows a flow diagram of further processing for dried fruits. The processstarts with dried material at a low-moisture level of about 5% to 6%. Thisproduct has to be inspected, classified by size, and graded. In the case of cutfruits, the size of the pieces or a size range is stated.

After grading, washing is the second most important operation becauseof the necessity to increase the moisture level up to the clients requirements.This operation has to be carried out with high-quality water that has nochemical residues, is low in metal contamination, and is low in chlorine.

Materials with the correct moisture content are sometimes treated with anantimycotic compound such as sorbate, but this operation depends on themoisture content of product and client specifications. Not all clients will acceptpreservatives added to their products. All products with more than 15%



moisture content need some type of food preservative for longer shelf life.

2

This processing step has a high correlation with the quality of products. Sincethe cost of this type of product is fairly high, the process has to be rigorouslycontrolled in all aspects of general quality, safety, and presentation.

11.4 Innovation in fruit dehydration

Major technical innovations in berry dehydration include sugar infusion andimpregnation under high or low pressure, microwave dehydration under vac-uum, and pulsed-mode microwave applications. There are several advantagesto the use of sugar infusion and impregnation, most related to improved flavor,texture, and color. These quality factors are very important for commercialacceptance, especially when products are used as industrial ingredients.

Sugar infusion is usually applied as a pretreatment before the finaldrying process because the moisture reduction is not always enough toreduce water activity to levels that will ensure preservation. Water activ-ity reduction by this method is normally in the range of 0.70 to 0.75.

Figure 11.3

Flow diagram for processing of dried fruits.

Stored driedmaterial


line

Dryscreening

Grading

Holding toaccumulatefruit graded

Blending toaccomplish

number/massWashing

Control ofmoisture to

requiredvalues

Dewateringby centrifuge

Cartonfilling

Warehousingand

shipping

Sorting

Inspectionincludingmagnetic



Infused products need to be further dehydrated using hot air or microwave/vacuum technology as a complementary process.

11.4.1 Osmotic dehydration

Osmotic dehydration process can be done using simple osmosis, osmoticdrying, or forced infusion using pressure changes. High pressure or vacuuminfusion produces more effective reductions in water activity to levels thatpermit fruit preservation. Osmotic dehydration consists of diffusion of sugarin a countercurrent mass transfer against water movement. As water isflowing out of the fruit due to the osmotic pressure difference, sugar solutionis flowing into the fruit. This process occurs as a result of chemical potentialgradients that affect the product-osmotic medium interface.

8

In the osmotic dehydration process, tissue maintains its condition, cellsare not disrupted, and cell membrane integrity remains intact. Sugar solu-tions are confined to intercellular spaces; they do not penetrate the cells dueto the cell membrane barrier. Most recent studies have been oriented towarddefining the kinetic models to apply osmotic drying to biological tissues.

8,9

For some berries, osmotic dehydration can be a problem due to their skinstructure, which can effect mass transfer, especially when the process is carriedout at a low temperature range of 45

°

C to 55

°

C. It is well known that temper-ature has an important impact on diffusion. It has been reported that hightemperatures significantly effect water diffusion from fruit tissues, due mainlyto swelling and plasticizing of membranes at high temperature. The faster thediffusion of water inside the fruit tissue, the higher the mass transfer on theproduct surface because of the lower viscosity of the medium.

8

Lazarides et al.

8

reported that different tissues in the same product havedifferent behaviors in the diffusion of osmotic solutions. Different tissues showdifferent porosities and pore connectivities—factors that greatly influencetransport phenomena—especially when the membranes maintain their integ-rity. This observation has been confirmed by several authors in the temperaturerange of 5

°

C to 40

°

C. In near room temperature osmosis, transport is relatedto the depth (location) of the tissues. Surface tissues suffer some changes, cellsplasmolyze quickly, but inner tissues show fully turgid cells for a longer time,especially when tissues are still alive.

9

This heterogeneity in tissue propertiesmakes it difficult to develop practical models to characterize the process.Berries are especially heterogeneous, and thus require new technologies inorder to minimize the effects of these tissue characteristics on the process. Thishas been the goal of many researchers when developing different technologiesto enhance mass transfer in osmotic dehydration.

Several factors are responsible for osmotic process efficiency, includingthe type and concentration of osmotic solution, temperature, size and shapeof the fruit, osmotic solution:fruit ratio, and the movement of solution byagitation. Improvement of the dehydration rate is very important, sinceosmotic drying is a rather slow process.

10,11

In order to improve the efficiency of mass transfer in osmotic dehydration,several studies have been carried out using vacuum, high pressure, and



high-intensity electric field pulses to enhance the process.

10,11

High pressure inthe range of 100 to 700 MPa for 5 minutes and a temperature of about 35

°

Cduring pressurization and about 15

°

C during decompression have been appliedto enhance mass transfer during osmotic drying. The temperature of theosmotic solution was in the range of 40

°

C to 50

°

C and the fruit:osmotic solutionratio was 1:25 in order to avoiding dilution of the latter. It was found that thediffusivity of water and solution in high-pressure materials was significantlyhigher than that of normal osmotic dehydration. This is evident up to a pressureof 400 MPa, above which diffusivity does not change significantly.

10

Another example of a coadjuvant technique is the use of a high-intensityelectrical field pulse (HELP). A HELP applied in carrots by Rastogi et al.

11

hadfive pulses, with an electric field strength of 0.22 to 1.60 kV/cm and a pulseduration of 378 to 405 µsec and a cell disintegration index (

Z

p

) of 0.09 to 0.84 (with0.0 for intact cell wall permeability and 1 for total cell disintegration). ThereforeHELP was responsible for increasing cell wall permeability, thus improving themass transfer in osmotic dehydration with sucrose as the osmotic agent.

Ade-Omowaye et al.

12

demonstrated the positive effect of using a com-bination of different solutes on the sensory quality of red paprika. Sucroseand sodium chloride were used, showing improved water and solid diffu-sion coefficients and equilibrium moisture and solid contents.

11.4.2 Microwave and combined microwave/vacuum processes

Several combinations of osmotic and other types of drying methods havebeen developed in last decade. A vacuum drying/microwave system usingcontinuous or pulsed energy was used to produce dehydration.

13

Thismethod is faster and produces more uniform heating than conventional airdehydration. In addition, quality and energy efficiency are improved.

Yongsawatdigul and Gunasekaran

13

studied the behavior of microwave/vacuum technology in producing high-quality dried cranberries. Eventhough microwave technology is recognized as a better process than airdrying, there are a few quality problems, such as texture and surface dryingrelated to temperature control in the process and the drying rate of thesurface tissues of the fruit.

14

Sunjka et al.

15

carried out a comparative studyof microwave/vacuum and microwave/convective drying and concludedthat there were no major differences in fruit color between these two meth-ods. The power level of the microwave is more important than the vacuumor hot air convective factor. The texture of dried fruit depends on the dryingmethod; microwave/vacuum-dried products are softer than microwave/convective-dried products. Organoleptic analysis shows that ordinary hotair convective drying is better than both microwave methods.

11.4.3 Vacuum infusion or impregnation process

This is a minimal process consisting of forced mass transfer to plant tissuesthat have been air evacuated by applying a vacuum. Plant tissues are firsttreated under a vacuum of 0.1 to 0.2 bar for several minutes and then infused



(or impregnated) with a solution containing different solutes, including cal-cium and hydrocolloids. To avoid potential impacts of pressure changes onthe product and to obtain the maximum mass rate during infusion or impreg-nation, an isotonic solution should be used in the process.

16

Several products have been tested with this technology, and the resultshave been very promising in whole and sliced apples, peaches, strawberries,pears, mushrooms, cucumbers, and peppers. Infusion solutions that have beenused include pectin, alginate, gums, ascorbic acid, malic acid, calcium, sugars,and sodium chloride. In most cases, the sensory characteristics and physicalproperties of the product are improved. This technique has been used as apretreatment for both drying and freezing processes, and has been demon-strated to be very useful for retaining firm texture, desirable color, and aroma.

Moreno et al.

17

reported that some quality attributes of Chilean papaya,including firmness and color, are different from those treated with osmoticdehydration when vacuum impregnation is applied, but the differences werenot significant and the product quality from both methods is similar. Masstransfer is slightly enhanced with the use of vacuum impregnation. Changesin pH were different: while the pH decreased with osmotic dehydration,probably due to enzymatic action, the pH increased with vacuum impreg-nation, probably due to acid lixiviation during the application of the pulsedvacuum at the beginning of the process. Both methods showed improvedquality of papaya tissues.

Roa et al.

18

proposed a mathematical model based on mass transferequations to predict final mass transfer and composition changes of productsthat have been vacuum impregnated. Pulsed vacuum impregnation wastested on several fruits, including papaya, pineapple, melon, apricot, andbanana (pineo gigante type). It was concluded that simple equations basedon the volumetric fraction and a measure of liquid adherence can be usedto produce a model that permits prediction of the final mass to an error ofless than 2.5% and composition to an error of less than 6%.

11.5 Critical quality and safety factors: Control of quality and nutritional losses during drying

Process conditions need to be controlled for two principal reasons: to ensure theprocess is economically efficient and to obtain a safe and high-quality product.Dehydration is a process with a huge impact on the quality of the final product.

11.5.1 Quality factors

The quality of dried fruits is affected by processing and storage conditions,including temperature, relative humidity, and other environmental condi-tions. Potential changes in texture, transformations of chemical compounds,and losses of color, flavor, and aroma can occur during processing andstorage. Thus drying conditions have to be carefully controlled to ensure aminimum impact on product quality. Hot air drying, in general, has a large



impact on quality, but even innovative drying techniques such as micro-wave/vacuum drying have some effect on product quality. The color ofberries is especially sensitive to the drying process, and strongly dependson process intensity, process length, temperature, and pretreatments applied.Fruit texture can also change, becoming firmer or softer, based on the natureof the fruit and the process applied.

Talens et al.

19

showed the effect of osmodehydration in preserving vol-atile compounds responsible for the aroma in strawberries. Osmotic pretreat-ment before freezing promoted formation of key compounds in the fruitaroma, preventing the loss of volatiles during freezing.

11.5.2 Nutritional and safety factors

Normally the effect of the drying process on the nutritional value of foodsis caused by the processing time instead of temperature: the longer theprocessing time, the larger the effect. Kwok et al.

20

studied the effects ofdifferent drying methods on quality in Saskatoon berries (

Amelanchier alni-folia

Nutt.). Hot air, freeze-drying, vacuum/microwave drying, and a com-bination of hot air and vacuum/microwave methods effected several qualityparameters, including total phenolics and anthocyanin content and antiox-idant activity. The best results were obtained by freeze-drying followed byvacuum/microwave drying. The worst results were obtained in berries driedusing hot air, and the second worst results were obtained for the combinationof hot air and vacuum/microwave drying. In this study, freeze-dried berrieswere first frozen at 35

°

C for 3 days. After 1 day of drying, the water activitywas 0.33 to 0.42. In spite of the long freezing period, this freezing methodresulted in better product quality.

Table 11.1 shows the effect of different dehydration methods on thequality of the berries, including color, antioxidant capacity, flavor, and taste.Almost all the drying methods had some effect on final product quality.

As discussed previously, water activity is a major factor in the preservationof dried products. This has to do with microbiological stability as well aschemical and biochemical stability. Chemical and enzymatic reactions requirewater, as the diffusion of chemical compounds or substrates and enzymes doesnot take place under low-moisture conditions. A low-water activity generallyproduces lower reaction rates.

6

Thus maintaining a low-moisture contentkeeps the product chemically and microbiologically stable.

11.5.3 Packaging

Packaging plays a very important role in preserving the quality of driedproducts. Dried berries are very hygroscopic and absorb moisture presentin the environment. The shelf life of dried berries depends on packaging andstorage conditions. Flexible materials are commonly used for dried foods.Cellophane, polypropylene, polyvinyl chloride (PVC), and other polymershave been the basis for better preservation of dried foods. New materials



not only have to have high gas and water vapor barrier properties, but alsoultraviolet (UV) light protection in order to control deterioration caused bylight. This function of packaging materials is critical for providing a barrierbetween the product and the environment, a barrier to microorganisms,transit protection, and protection from physical, chemical, and sensorychanges.

In order to maintain good barrier properties, containers have to be her-metically sealed to avoid oxygen, vapor, and volatiles transfer. Moisture cancause significant losses in product quality. Since oxygen contributes to anumber of deteriorative reactions, this gas has to be removed from thecontainer. Berries are characterized by their unique colors, flavors, and aro-mas, and should be maintained in hermetically sealed containers to avoidpigment oxidation, chemical transformation of sugars, changes in texture bycrystallization, and loss of texture by humectation.

11.6 Applications of dried berry fruit

There are many uses for dried berries. Most are classified as ingredients inother foods. In some of these products, food preservatives may be added toextend shelf life.

11.6.1 Snack foods

One of the most popular products in recent years has been the fruit snack. It is anintermediate moisture product that includes a mixture of cereals and dried fruitstabilized with some permitted food preservative. These products contain wild orcultivated berries and are popular because of the recognized health benefits ofberries associated with their antioxidant activity, scavenging of free radicals, andhigh content on soluble dietary fiber. These snacks may also include other ingre-dients besides dried fruit and cereals, including dried yogurt or honey.

11.6.2 Breakfast cereals

The addition of berries to breakfast cereals has become very popular becauseof the healthy attributes of berries. The benefits of soluble dietary fiber fromberries complement very well the insoluble fiber of cereals. Fruit added tobreakfast cereals are medium moisture, and coatings are sometimes appliedto the surface of the fruit to prevent cereal humectation by fruit moisture.When low-moisture fruit is used, the texture of the fruit may not be accept-able at the moment the cereal is mixed with milk or juice. In some cases,berries are laminated after drying so they will have a better texture, butnormally they are softened by the addition of water vapor or some type of oil.

11.6.3 Formulated foods

Dried berries can be used as food ingredients in a wide variety of differentproducts, including ice cream, toppings, fruit pieces in pastries and cookies,yogurt, snacks, and pressed for fruit leathers. In some of these products, a



second heat treatment could be deleterious to the chemical quality of thedried fruit. In this case, it is better to use dried fruits that are protectedagainst deterioration of these compounds.

11.7 ConclusionDehydration is a valuable solution for the preservation of berries. Differentdehydration methods are available to process this high-value product, butsome methods may be more suitable than the others depending on therequirements of the final product, available facilities, investment costs, andtechnical capacity. Sun drying is a low-cost method, but care is needed inorder to ensure product quality and microbial safety. Other methods, suchas freeze-drying and microwave/vacuum drying, that provide high qualityproducts with high values are more expensive. In the middle, there areseveral conventional methods that use water removal and water activitydepression to preserve the product. Dehydration, when starting withhigh-quality raw materials, applying appropriate drying methods, and usingproper packaging, can preserve berries for a long time with high quality.Dried berries have broad applications as snacks or as functional food ingre-dients in many different types of manufactured foods.

References1. Van Arsdel, W.B., Copley, M.J., and Morgan, A.I., Food Dehydration, 2nd ed.,

Vol. 1, Avi Publishing, Westport, CT, 1973, p. 347.2. Van Arsdel, W.B., Copley, M.J., and Morgan, A.I., Food Dehydration, Vol. 2, Avi

Publishing, Westport, CT, 1973, p. 529.3. Fellows, P., Food Processing Technology, CRC Press, Boca Raton, FL, 2000, p. 591.4. Crapiste, G.H. and Rotstein, E., Design and performance evaluation of dryers,

in Handbook of Food Engineering Practice, Valentas, K.J., Rotstein, E., and Singh,R.P., Eds., CRC Press, Boca Raton, FL, 1997, chap. 4.

5. Roos, Y.H., Water activity and plasticization, in Food Shelf Life Stability: Chemical,Biochemical, and Microbiological Changes, Eskin, N.A.M. and Robinson, D.S.,Eds., CRC Press, Boca Raton, FL, 2001, chap. 1.

6. St. George, S.D., Cenkowski, S., and Muir, W.E., A review of drying technol-ogies for the preservation of nutritional compounds in waxy skinned fruit,Paper no. 04-104, 2004 North Central ASAE/CSAE Conference, September24–25, 2004, Winnipeg, Manitoba, Canada.

7. Grabowski, S., Marcotte, M., Poirier, M., and Kudra, T., Drying characteristicsof osmotically pretreated cranberries—energy and quality aspects, DryingTechnol., 20, 1989, 2002.

8. Lazarides, H.N., Fito, P., Chiralt, A., Gekas, V., and Lenar, A., Advances inosmotic dehydration, in Processing of Foods: Quality Optimization and ProcessAssessment in Conventional and Emerging Technologies, Oliveira, F.A.R. andOliveira, J.C., Eds., CRC Press, Boca Raton, FL, 1999, chap. 11.

9. Salvatori, D., Andres, A., Albors, A., Chiralt, A., and Fito, P., Structural andcompositional profiles in osmotically dehydrated apple, J. Food Sci., 63, 606,1998.



10. Rastogi, N. and Niranjan, K., Enhanced mass transfer during osmotic dehy-dration of high pressure treated pineapple, J. Food Sci., 63, 508, 1998.

11. Rastogi, N., Eshtiaghi, M., and Knorr, D., Accelerated mass transfer duringosmotic dehydration of intensity electrical field pulse pretreated carrots,J. Food Sci., 64, 1020, 1999.

12. Ade-Omowaye, B.I.O., Rastogi, N.K., Angersbach, A., and Knorr, D., Osmoticdehydration behavior of red paprika (Capsicum annum L.), J. Food Sci.,67, 1790, 2002.

13. Yongsawatdigul, J. and Gunasekaran, S., Microwave-vacuum drying of cran-berries: part II. Quality evaluation, J. Food Proc. Preserv., 20, 145, 1996.

14. Jolly, P.G., Temperature controlled combined microwave-convection drying,J. Microwave Power, 22, 65, 1986.

15. Sunjka, P.S., Rennie, T.J., Beaudry, C., and Raghavan, G.S.V., Microwave-convective and microwave-vacuum drying of cranberries: a comparativestudy, Drying Technol., 22, 1217, 2004.

16. Martinez-Monteagudo, S.I., Salais-Fierro, F., Perez-Carrillo, J.R., Valdez-Fragoso, A., Welti-Chanes, J., and Müjica-Paz, H., Impregnation and infiltra-tion kinetics of isotonic solution in whole jalapeño pepper using a vacuumpulse, J. Food Sci., 71, E125, 2006.

17. Moreno, J., Bugueno, G., Velasco, V., Petzold, G., and Tabilo-Munizaga,G., Osmotic dehydration and vacuum impregnation on physicochemicalproperties of Chilean papaya (Carica candamarcensis), J. Food Sci., 69, E102, 2004.

18. Roa, V., Tapia, M.S., and Millan, F., Mass balances in porous food impregna-tion, J. Food Sci., 66, 1332, 2001.

19. Talens, P., Escriche, I., Martinez-Navarrete, N., and Chiralt, A., Study of theinfluence of osmotic dehydration and freezing on the volatile profile of straw-berries, J. Food Sci., 67, 1648, 2002.

20. Kwok, B.H.L., Hu, C., Durance, T., and Kitts, D.D., Dehydration techniquesaffect phytochemical contents and free radical scavenging activities of Saska-toon berries (Amelanchier alnifolia Nutt.), J. Food Sci., 69, S122, 2004.


335

chapter 12

Commercial canningof berries

Hosahalli S. Ramaswamy and Yang Meng

Contents

12.1 Introduction ............................................................................................... 33612.2 Canning principles.................................................................................... 337

12.2.1 Target microorganisms or enzymes .......................................... 33812.2.2 Microflora in canned berry fruits .............................................. 33912.2.3 Composition of berry fruits........................................................ 33912.2.4 Microbial destruction kinetics.................................................... 340

12.2.4.1 Survivor curve and D value ........................................ 34012.2.4.2 Thermal inactivation time of enzymes ...................... 34112.2.4.3 Temperature dependence and

z

value ....................... 34212.2.4.4 Lethality .......................................................................... 342

12.2.5 Heat penetration test ................................................................... 34312.2.6 Thermal process calculations ..................................................... 345

12.2.6.1 General methods............................................................ 34512.2.6.2 Formula methods........................................................... 346

12.3 Process calculations .................................................................................. 34712.4 Canning operations .................................................................................. 349

12.4.1 Raw material selection ................................................................ 35112.4.2 Washing.......................................................................................... 35112.4.3 Sorting/grading............................................................................ 35212.4.4 Filling ............................................................................................. 352

12.4.4.1 Type of pack ...................................................................35212.4.4.2 Type of covering liquid ................................................ 35212.4.4.3 Container specifications and types ............................35312.4.4.4 Container sizes............................................................... 35312.4.4.5 Can lacquer..................................................................... 354

5802_C012.fm Page 335 Monday, April 30, 2007 5:05 PM


12.4.5 Exhausting and vacuum ............................................................. 35412.4.6 Seaming/closing........................................................................... 35512.4.7 Container coding.......................................................................... 35512.4.8 Retort operations .......................................................................... 35512.4.9 Cooling........................................................................................... 35612.4.10 Labeling and storage ...................................................................357

12.5 Grades of canned berries......................................................................... 35712.6 Canning of berry fruit .............................................................................. 358

12.6.1 Blackberry...................................................................................... 35812.6.2 Blueberry ....................................................................................... 35912.6.3 Black currant ................................................................................. 35912.6.4 Cranberry....................................................................................... 36012.6.5 Gooseberry .................................................................................... 36012.6.6 Loganberry .................................................................................... 36112.6.7 Raspberry....................................................................................... 36112.6.8 Strawberry ..................................................................................... 361

Nomenclature ......................................................................................................363References ........................................................................................................... 364

12.1 Introduction

Since ancient times, several techniques have been used for the preservation ofberry fruits and their products: drying, concentration, freezing, fermentation,and chemical preservation by use of vinegar, wine, sugar, and spices. SinceNicholas Appert proposed the processing method of canning foods in 1809,canning has proven to be one of the most effective techniques used for fruitpreservation.

1

In the early stages of this method, food was placed intowide-mouthed glass bottles or jars and carefully corked, after which they wereheated in boiling water. It was believed that if food is sufficiently heated andsealed in an airtight container, it will not spoil. Louis Pasteur, in 1864, demon-strated that food spoilage is caused by the growth of microorganisms and heatcan kill microorganisms. The basic principles of canning have not changed dra-matically since Nicholas Appert developed the process: provide enough heat todestroy the microorganisms in foods enclosed in a hermetically sealed container.

By the turn of the century, significant progress in microbiology and theheating behavior of packaged foods led to scientific approaches in thermalprocess calculation. In the 1910s and 1920s, the basic biological and toxico-logical characteristics of

Clostridium botulinum

were first determined by sev-eral researchers. The importance of controlling

C. botulinum

in canned foodsbecame clear and the basis for its control was established. A detailed histor-ical perspective of the developments in thermal processing is provided byLopez.

2

In 1920, Bigelow et al. developed the “general method,” which isthe first scientifically based process calculation method. Ball

3

developed the“Ball formula method.” In 1950, Stumbo revised the Ball formula methodand made the process calculation more versatile and accurate. The general


Chapter 12: Commercial canning of berries 337

method and formula method are still the basic procedures used for processcalculations in canning industry. In the last few decades, Pflug,

4

Hayakawa,

5,6

Teixeira et al.,

7

Griffin et al.,

8,9

Manson et al.,

10

Tung and Garland,

11

Ramaswamy et al.,

12

Pham,

13

and many others have further refined mathe-matical heat process determination concepts and applications.

The intervening period also saw significant developments in the manufac-turing of thermal processing equipment in the form of improved versions ofthe retort system. Next in the line of process equipment were continuous sys-tems for thermal sterilization of food cans and glass jars and systems for han-dling high-temperature, short-time (HTST) processes in batch or continuousmodes in still or rotary autoclaves. Developments such as aseptic processingand packaging, thin profile processing, fully automated agitating retorts, andretort systems based on different media have revolutionized the food industry.

14

New processes such as combined methods technology

15

are continually beingintroduced, especially for heat-sensitive products such as berry fruits, to pre-serve overall color, flavor, and other quality attributes. Berry fruits, in general,are commodities with special organoleptic properties that must be carefullypreserved when establishing operating conditions for a thermal process.

12.2 Canning principles

Canning is the most commonly used technique to heat sterilize foods inorder to prevent microbiological and enzymatic spoilage. A variety of foodsare canned, including meat, fish, poultry, fruit, dairy, and vegetable products.Heat processes used for these foods are dependent on the type of the food,its chemical composition, and the types of microorganisms that cause spoil-age or public health concerns, in addition to properties related to containermaterial, shape, and size, as well as properties related to the heating medium.

Any thermal process for a food should be designed to achieve three basicobjectives, the most important being to reduce the number of microorgan-isms to statistically small levels, whether they are of public health concernor of the spoilage type, which cause off-flavors and odors. The second objec-tive is to create an environment in the container that will suppress the growthor activity of spoilage-type microorganisms by utilizing one or more of thefollowing methods: (1) oxygen removal, (2) pH control, and (3) control ofstorage temperature. The third objective is to ensure an adequate or hermeticseal of the container to prevent recontamination following processing andduring storage. Thermal processing is not intended to completely sterilizethe packaged food. Such an approach might produce a stable product, butit will be at the expense of severe destruction of product quality. The successof thermal processing depends on selectively destroying the microorganismsof spoilage and public health concern while creating an environment aroundthe product to minimize the growth and activity of other microorganisms.

In order to determine the extent of heat treatment, several factors mustbe known:

16

(1) The type and the heat resistance of the target microorganism,spore, or enzyme present in the food; (2) the pH of the food; (3) the storage



conditions following the process; (4) heating conditions; and (5) thermophysicalproperties of the food, and container shape and size.

12.2.1 Target microorganisms or enzymes

The first step in designing a thermal process is to verify the target microor-ganisms or enzymes upon which the process should be based. Several factorsshould be considered. For example, in foods that are packaged under vacuumin hermetically sealed containers, low oxygen levels are achieved. The aerobicmicroorganisms that require oxygen thus have no supporting environmentto exist. In addition, spores of the aerobic microorganisms are less heat resis-tant than anaerobic microorganisms. Therefore the target microorganismsshould be anaerobic microorganisms. Considering that the growth and activ-ity of most anaerobic microorganisms are pH dependent, foods are generallyclassified based on their pH values. From a thermal processing point of view,foods are divided into three pH groups: high-acid foods (pH

<

3.7), acid ormedium-acid foods (3.7

<

pH

<

4.5), and low-acid foods (pH

>

4.5). Examplesof foods in each group are as follows: high-acid foods include apple, applejuice, apple cider, applesauce, berries, cherry (red sour), cranberry juice, cran-berry sauce, fruit jellies, grapefruit juice, grape fruit pulp, lemon juice, limejuice, orange juice, plum, pineapple juice, sour pickles, sauerkraut, and vin-egar; medium acid foods include fruit jams, fruit cocktail, grapes, tomato,tomato juice, peaches, pineapple slices, potato salad, prune juice, and vege-table juice; and low-acid foods include meat, fish, vegetables, mixed entrees(beans and pork, chicken with noodles, etc.), and most soups.

17

For low-acid foods (pH

>

4.5), the target microorganism is

C. botulinum

.It is a highly heat-resistant, rod-shaped, spore-forming, anaerobic pathogen,and if it is not destroyed by the heat treatment, it can thrive and produce adeadly botulism toxin when stored under anaerobic conditions at ambienttemperatures. It has been generally recognized that

C.

botulinum

does notgrow and produce toxin at a pH of less than 4.6. Hence the dividing pHbetween the low-acid and acid groups is set at 4.5 such that in medium- andhigh-acid foods (pH

<

4.5) it is not necessary to worry about

C.

botulinum

.Berry fruits and their products are mostly considered as high-acid foods(pH

<

3.7). Other anaerobic microorganisms that are more heat resistant than

C.

botulinum

, such as

Bacillus stearothermophilus

,

Bacillus thermoacidurans

, and

Clostridium thermosaccolyticum

, although highly heat resistant, low-acid, andspore forming, are of little concern if the processed cans are stored at tem-peratures below 30

°

C, because they are generally thermophilic in nature(optimal growth temperature approximately 50

°

C to 55

°

C).Anaerobic, spore-forming microorganisms are so heat resistant that nor-

mally severe heat treatment (sterilization at temperatures greater than 110

°

C)is used for long-term storage under elevated storage temperature conditions.For acid and medium-acid foods (pH

<

4.5),

C. botulinum

and most sporeformers will not grow and the target of the thermal process is usually theheat resistant, spoilage-type vegetative bacteria or enzymes, which are easilydestroyed, even by a mild heat treatment (pasteurization in boiling water).

18



If not inactivated following thermal processing, several heat-resistantenzymes in fruits (including peroxidase, pectin esterase, lipoxygenase, cat-alase, and polyphenol oxidase) may cause undesirable quality changes inthe final canned product during storage, especially related to color, texture,and flavor. For thermal processing of acid foods, such as berry fruits, inac-tivation of these enzyme systems is often used as a basis because they usuallypossess a higher thermal resistance than the microorganisms present in thefood. As peroxidase is known to have a very high heat resistance, its destruc-tion is often used as an adequate marker for the destruction of all heat-resistant enzymes present in the food. Nevertheless, the heat resistance ofenzymes varies with the fruit, its variety, pH, and total soluble solids.

19

12.2.2 Microflora in canned berry fruits

Of the three groups of microorganisms, yeasts are heat sensitive; a 5-minuteexposure to 66

°

C destroys living forms and the same exposure time at about80

°

C destroys spores. Non-spore-forming bacteria are also very heat sensi-tive. Obviously the heat process for the preservation of berry fruits will notnecessarily kill spore-forming bacteria such as

C. botulinum

; however, theyare unlikely to cause problems even if they are present.

Molds in canned berry fruits are quite insignificant because some aredestroyed with spores in 30 minutes at about 66

°

C, the effect being greaterin anaerobic conditions. Some molds possess an extremely high resistanceto heat in canned acid foods, including the species

Byssochlamys

,

Paecilomyces

,and

Phialophora

.

Byssochlamys fulva

is exceptionally heat resistant as it breaksdown pectinous materials, disintegrating fruit and sometimes producinggas. Its limited ability to grow in the presence of air permits its growth inproducts such as sterilized compotes and jams. It has been found that

B. fulva

is more heat resistant in foods containing citric acid,

20

which is the mostimportant organic acid in berry fruits.

The thermal resistance of microorganisms in fruits depends upon vari-ous factors, such as the amount and type of sugar present, the pH, and thetype of acid.

21

Organic acids have a detrimental effect on microorganismsdue to the toxicity of the hydrogen ion and the undissociated molecule.Lower pH levels are more toxic to bacteria, which explains the addition ofan acidulant to adjust the pH to a standard value, often allowing for a shortersterilization time. In some instances, however, decreasing the temperatureis also possible. Different acids possess various levels of effectiveness inlowering the heat resistance of microorganisms. This order is lactic acid

>

citric acid

>

acetic acid. Based on the pH of the product, the order is aceticacid

>

citric acid

>

lactic acid.

19

12.2.3 Composition of berry fruits

The acids present in berries are advantageous for preservation, especially becausethey have a bacteriostatic effect. In good-quality berry fruits ready for processing,the organic acid most frequently encountered is citric acid.

20

In blueberries,



40% of the organic acids present is quinic acid. Organic acids reach peak levelsin fruits just as they reach the ripeness stage. The organic acids content tends todecrease in several types of fruit at the end of the ripening period throughconversion to sugars. Thus the acid content decreases while the sugar contentincreases. During storage, the acid is consumed through respiration.

Berry fruits are rich in sugars; however, their levels depend on a varietyof factors, such as species, soil, location, and the ripening stage. Sugar levelsgenerally range between 0.5% and 25%. When the fruit is detached from themother plant, sugar levels decrease due to the increase in respiration rate(cells consume sugar). In maturing fruit, the total sugar content rises for twomain reasons: (1) hydrolysis of polysaccharides and (2) formation of sugarsas secondary products following acid conversion.

12.2.4 Microbial destruction kinetics

Target microorganisms for thermal destruction in a food vary according to thetype of food and the composition. Thus these target components and theirrespective thermal resistances determine the thermal process itself. To establisha thermal processing schedule, the thermal destruction rates of the targetmicroorganisms must be determined under the conditions that normally pre-vail in the container so that an appropriate heating time can be determined ata given temperature. Furthermore, because packaged foods cannot be heatedto process temperatures instantaneously, data on the temperature dependenceof the microbial destruction rate are also needed to integrate the destructioneffect through the temperature profile under processing conditions.

12.2.4.1 Survivor curve and

D

value

Normally the thermal destruction of microorganisms is traditionallyassumed to follow first-order inactivation kinetics, with their destructionbeing a semilogarithmic function of time at a constant temperature, whichignores any lag or tailing phenomena that could be important. In otherwords, the logarithm of the surviving number of microorganisms in a heattreatment at a particular temperature plotted against the heating time willgive a straight-line curve known as the survivor curve (Figure 12.1). Themicrobial destruction rate at a given temperature is defined as the decimalreduction time (

D

value), which is the heating time in minutes at a giventemperature required to cause a one decimal reduction in the survivingmicrobial population. Graphically this represents the time range betweenwhich the survival curve passes through one logarithmic cycle (Figure 12.1).Mathematically it can be written as

, (12.1)

where

N

1

and

N

2

represent the microbial population at time

t

1

and

t

2

, respectively.

Dt t

NN

=−⎡⎣⎢

⎤⎦⎥

2 1

1

2log



The logarithmic nature of the survivor curve indicates that the completedestruction of a microbial population is not theoretically possible because adecimal fraction of the population should remain even after an infinitenumber of

D

values. In food microbiology, another term that generally con-tradicts this logarithmic destruction approach is often employed: thermaldeath time (TDT), which is the heating time required to cause completemicrobial destruction. Such data are obtained by subjecting a microbial pop-ulation to a series of heat treatments at a given temperature and testing forsurvivors. The death in this instance generally indicates the failure of a givenmicrobial population after the heat treatment to show a positive growth inthe subculture media. Comparing the TDT approach with the decimal reduc-tion approach, it can easily be seen that the TDT value depends on the initialmicrobial load (while the

D

value does not). Furthermore, the TDT representsa multiple of the

D

value. For example, if the TDT represents the time toreduce a population from 10

12

to 10

0

, then the TDT is a measure of 12

D

values, or

TDT

=

nD

, (12.2)

where

n

is the number of decimal reductions.

12.2.4.2 Thermal inactivation time of enzymes

The thermal inactivation curve for enzymes is established in a manner sim-ilar to that of the TDT curve for bacteria. This is done by subjecting the foodsample to a series of heat treatments at a specific temperature and testingfor residual enzyme concentrations. When there is no measurable residualactivity, the enzyme is considered inactivated and the corresponding heatingtime is called the thermal inactivation time (TIT).

Since most enzyme systems in berry fruits (peroxidase, pectinesterase,and polyphenol oxidase) generally possess a higher thermal resistance than

Figure 12.1

A typical survivor curve.

10

100

1000

10000

100000

0 5 10 15 20

Heating time (min)

Num

ber

of s

urvi

vors

D



microorganisms, the calculation of the process time for canned berry fruitsis based on the TIT of the most heat-resistant enzyme present in the product.

12.2.4.3 Temperature dependence and

z

value

The temperature sensitivity of

D

values at various temperatures is normallyexpressed as a thermal resistance curve with log

D

values plotted againsttemperature (Figure 12.2). The temperature sensitivity indicator is called the

z

value, which represents a temperature range that results in a 10-fold changein

D

values, or graphically it represents the temperature range through whichthe

D

value curve passes through one logarithmic cycle. Mathematically itcan be written as

, (12.3)

where

D

1

and

D

2

are

D

values at temperature

T

1

and T2 (in °C), respectively.

12.2.4.4 LethalityThe effectiveness of a thermal process in killing microorganisms or inacti-vating enzymes in a food product may be denoted by the lethality; in otherwords, the lethality is a measure of the effectiveness of the heat treatment.To compare the relative sterilizing capacities of different heat processes,lethality (F0 value) is defined as an equivalent heating time at a referencetemperature, which is usually taken to be 121°C for sterilization or 82°C forpasteurization. The F0 value can be expressed as

(12.4)

Figure 12.2 A typical thermal resistance curve.

1

10

100

1000

90 95 100 105 110

Temperature (°C)

D v

alue

(m

in)

Z

zT T

DD

=−⎡⎣⎢

⎤⎦⎥

2 1

1

2log

Lethality or F FT T

z0 = ×

−

100

,



where T0 is the reference temperature and F is the heating time at temperature T.Thus an F value of 2 minutes at 88°C is equivalent to an F0 value of 20 minutesat 82°C, while the same F value at 85°C is equivalent to an F0 value of6.3 minutes at 82°F when z = 6°C. For real thermal processes, heating to theappropriate temperature and the subsequent cooling are not instantaneous,where the food passes through a time-temperature profile. It is possible to usethis concept to integrate the lethal effects through the various time-temperaturecombinations. The combined lethality thus obtained for a process is calledthe process lethality and is also represented by the symbol F0. The term alwaysapplies to a specific location in the product container or the slowest heatingpoint (cold spot). For conduction heating, the cold spot is the thermal center,whereas for convection heating, it is located approximately one-tenth of thelength of the can from the bottom. Generally it is assumed that if the coldspot receives an adequate process lethality, then all other points within thecontainer will receive an equal or greater process lethality.

The criterion for the adequacy of a thermal process is normally based onmicrobiological consideration, especially for low-acid foods for which theminimal criterion is the destruction of C. botulinum spores. It has been arbi-trarily established that the minimum process should be severe enough toreduce the population of C. botulinum through 12 decimal reductions (the “botcook”). Based on published information, a decimal reduction time of 0.21 minutesat 121°C is normally assumed for C. botulinum.22 A 12-decimal reductionwould thus be equivalent to an F0 value of 12 × 0.21 = 2.52 minutes. Theminimal process lethality (F0) required is therefore 2.52 minutes. In practice,an F0 value of 5 minutes is perhaps more common for low-acid foods. Thereason is the occurrence of more heat-resistant spoilage-type microorganismsthat are not a public health concern. The average D value for these spoilagemicroorganisms is about 1 minute. An F0 value of 5 minutes would only beadequate to achieve a 5D process with reference to these spoilage microor-ganisms. Thus it is essential to control the raw material quality to keep theinitial count of these organisms below 100 per container on average if thespoilage rate is to be kept below 1 can in 1000 (102 to 10−3 = 5D).

In the case of acid foods, such as berry fruits, the criterion for theadequacy of the process is based more specifically on the reduction in theamount of spoilage-causing bacteria and inactivation of the most heat-resistantenzymes present. The two objectives of thermal process calculations are (1)to estimate how much destruction a given process will accomplish and (2)to arrive at an appropriate process time required to accomplish the desiredlevel of destruction or inactivation (in the case of enzymes). In order to attainthese two objectives, thermal destruction kinetics and the product heatingprofile must be obtained.

12.2.5 Heat penetration test

In order to establish thermal process schedules, information on the temper-ature history of the product going through the process is needed in addition



to thermal resistance characteristics of the target microorganisms or enzymes.A heat penetration test is carried out to gather the time-temperature data,normally with a thermocouple measuring the product temperatures.Simple time-temperature curves during heating and cooling of conductionand convection heating are shown in Figure 12.3.

Heat penetration parameters are obtained from a plot of the logarithmof the temperature difference between the retort and the product center,known as the temperature deficit (TR − T during heating and T − Tw duringcooling), against time on a linear scale. For the heating process, as shown inFigure 12.4, a straight line is obtained after the initial lag. By extending the

Figure 12.3 Typical heat penetration curves.

Figure 12.4 Heat penetration parameters.

60

80

100

120

0 20 40 60 80

Process time (min)

Tem

per

atu

re (

°C)

Convection heatingConduction heatingRetort temperature

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 10 20 30 40 50 60

Heating time (min)

Lo

g (

TR–T

)

fh

log(TR–Tih)

log(TR−Tpih)

jch=(TR–Tpih)/(TR–Tih)



straight line portion of the curve to the y axis representing Tpih, the heatinglag factor (jch) is obtained (see Equation 12.5). jch is a measure of the thermallag (or delay) in heating the product. Part of the lag is due to the come-uptime of the retort, and this can be accounted for by determining the newzero time for the process. Ball and Olson23 used 58% of the come-up time asa useful contribution to the process, and this is widely accepted.24 Thisimplies that 42% of the come-up time should be added to the process timeat retort temperature.

(12.5)

The slope of the line (Figure 12.4) represents the time for the curve totraverse one log cycle. The negative reciprocal of this slope is referred toas the heating rate index (fh). fh is an indicator of the heating rate. Thehigher the value, the longer it takes for the log to traverse one cycle,indicating a slow rate of heat penetration. For the cooling process, a similarapproach can be used to get the cooling parameters: the cooling rate index (fc)and the cooling lag factor (jcc).22

12.2.6 Thermal process calculations

Thermal process calculations are carried out using thermal destructionkinetics of target microorganisms or enzymes and heat penetration param-eters. The purpose of thermal process calculations is to determine therequired process time under a given set of heating conditions that resultsin the required process lethality, or alternatively, to estimate the achievedlethality of a process. The process calculation methods are broadly dividedinto two classes: (1) general methods and (2) formula methods. The generalmethods integrate the lethal effects by a graphical or numerical integrationprocedure based on the time-temperature profiles obtained from the testcontainers processed under actual commercial processing conditions. For-mula methods, on the other hand, make use of the heat penetration param-eters together with several mathematical procedures to integrate the lethaleffects.14

12.2.6.1 General methodsIn the original general method, the reciprocal of the TDT is defined as thelethal rate at the corresponding temperature. A lethal rate curve is drawnby plotting the lethal rate against the heating time; the area under this curveyields the sterilization value of the process. A sterilization value of unity isthe minimal requirement with respect to the target microorganism orenzyme. If the resulting sterilization value is greater than or less than thedesired value, the cooling curve is shifted manually to the left or right andthe procedure is repeated to get the new sterilization value. This whole

jT T

T TchR pih

R

=−− 0



process is repeated until the desired sterilization value is obtained and thecorresponding process time is noted.

The improved general method, devised by Ball,3 calculates the processlethality F0 value at the reference temperature T0 with graphical or numericalintegration of Equation 12.6:

(12.6)

where is the lethal rate (L value) at any temperature T.The general method is the most accurate method for determining the

sterilization value of a heat process. It is used as a basic method for calcu-lating the F0 value used to compare the performance of the formula methods.While the results of the general method are very specific to the product underthe conditions employed for testing, extrapolation and generalization shouldbe avoided.

12.2.6.2 Formula methodsThe formula methods are based on characterizing heat penetration data andcombining kinetic data with heat penetration parameters. Ball’s method3 isthe simplest and most widely used technique for process calculations. It isbased on the following equations derived from the heat penetration curveto estimate the process time, B (in minutes):

, (12.7)

Ih = TR − Ti, (12.8)gc = TR − Tic, (12.9)

where B is the process time (in minutes), fh is the heating rate index (inminutes), jch is the heating lag factor, Ih is the initial temperature differenceat the start of heating process, TR is the retort temperature, Ti is the initialproduct temperature, and gc is the temperature difference at the end ofheating or beginning of cooling, respectively. The determination of gc is thekey to estimating the process time. Ball provided the relationship betweenfh/U and gc in the form of a table as well as in figure format. U is numericallyequivalent to

U = F0Fi (12.10)

, (12.11)

where F0 is the desired process lethality and Fi is the number of minutes at theretort temperature (TR) equivalent to 1 minute at the reference temperature, T0.

F dtT T

zt

0010

0

=−

∫ ,

10 0( )/T T z−

B fj Ighch h

c

=⎛

⎝⎜⎜

⎞

⎠⎟⎟log

Fi

T T

zR

=−

100



In deriving these relationships, Ball assumed (1) the cooling rate index(fc) is equal to the heating rate index (fh); (2) the cooling lag factor jcc is 1.41;(3) the z value is 10°C; and (4) the effectiveness of the come-up time is 42%.These assumptions give some limitations to the use of Ball’s method.

In order to overcome the limitations of Ball’s method, Stumbo andLongley25 published revised tables for process calculations, taking intoaccount the variability of jcc and z values. Stumbo’s method is very flexible;it can accommodate the destruction of bacteria spores, vegetative cells, ornutrients, all of which possess different thermal resistances (D and z values).All types of thermal processes can be calculated; for example, the z value ofa typical pasteurization process is 5.6°C (vegetative bacteria), that of asterilization process is 10°C (C. botulinum), and that of nutrients is typically22°C to 28°C. Table 12.1 shows the fh/U versus gc relationships (z = 5.6°C)necessary for typical pasteurization processes.22

Formula methods can be used to determine the process time if the targetprocess lethality F0 value is known and it can also be used to calculate thedelivered lethality of a given process. Since it uses heat penetration data inthe form of parameters (fh, jch, and jcc) for the same product in many differentcontainers, different retort temperatures (TR), or different initial producttemperatures (Ti), new processes can be calculated directly using availableparameter conversion procedures.

12.3 Process calculationsHeat processing is quite clearly the most destructive method of berry fruitprocessing. Since berry fruits are high in organic acids, such as citric andquinic acid, their overall pH is quite low and they require much less rigorousheat treatment as compared to low-acid foods such as meats.

In order to establish a processing schedule for canned berry fruits sub-jected to pasteurization, the most heat-resistant microorganism of publichealth concern in the container must be identified and evaluated for itsthermal destruction rate. In most cases, however, it is the most heat-resistantenzyme system and vegetative bacteria that are used as the basis for estab-lishing the thermal process. The thermal inactivation time for the particularenzyme, which is usually peroxidase, should be adequate to provide a micro-biologically safe berry fruit product. In contrast to the destruction of sporesduring the sterilization process, the pasteurization process targets vegetativecells only. The D and z values of these vegetative cells are much smaller thanthose of spores. This decreased thermal resistance permits the use of lowerprocessing temperatures.

With reference to berry fruit pasteurization, first, the reference temper-ature is changed from 121°C to a lower value, typically 85°C. In addition,the reference z value is changed from 10°C to 5.6°C. Process calculations canthen be performed by either the general or formula method. A typical processcalculation using the improved general method (numerical integration tech-nique) is shown in Table 12.2.



ble

12.1

f h/U

Rel

atio

nshi

ps W

hen

z =

5.6°

C (

10°F

)

Valu

es o

f g c

(°F

) w

hen

j o

f co

olin

g cu

rve

isf h

/U0.

40.

60.

81.

001.

201.

401.

601.

802.

00

0.2

2.68

E-0

.52.

78E

-0.5

2.88

E-0

.52.

98E

-0.5

3.07

E-0

.53.

17E

-0.5

3.27

E-0

.53.

36E

-0.5

3.46

E-0

.50.

52.

10E

-0.2

2.21

E-0

.22.

40E

-0.2

2.60

E-0

.22.

79E

-0.2

2.99

E-0

.23.

18E

-0.2

3.38

E-0

.23.

57E

-0.2

1.00

0.28

20.

294

0.30

50.

317

0.32

90.

340

0.35

20.

364

0.37

62.

001.

141.

171.

191.

211.

291.

261.

291.

311.

333.

001.

831.

881.

921.

972.

012.

052.

102.

142.

194.

002.

332.

412.

482.

552.

632.

702.

772.

852.

925.

002.

712.

812.

923.

033.

143.

243.

353.

463.

576.

003.

013.

153.

293.

433.

573.

723.

864.

004.

147.

003.

253.

433.

613.

783.

964.

134.

314.

494.

668.

003.

473.

683.

894.

104.

304.

514.

724.

935.

149.

003.

673.

904.

144.

384.

624.

855.

095.

335.

5710

.00

3.84

4.11

4.38

4.64

4.91

5.17

5.44

5.70

5.97

20.0

05.

225.

676.

126.

577.

017.

467.

918.

358.

8030

.00

6.27

6.81

7.34

7.88

8.41

8.95

9.48

10.0

10.6

40.0

07.

147.

728.

318.

899.

4810

.110

.711

.211

.850

.00

7.87

8.49

9.10

9.72

10.3

11.0

11.6

12.2

12.8

60.0

08.

519.

159.

7810

.411

.111

.712

.313

.013

.670

.00

9.07

9.72

10.4

11.0

11.7

12.3

13.0

13.6

14.3

80.0

09.

5610

.210

.911

.612

.212

.913

.614

.214

.990

.00

10.0

10.7

11.4

12.0

12.7

13.4

14.1

14.7

15.4

100.

0010

.411

.111

.812

.513

.113

.814

.515

.215

.920

0.00

13.0

13.7

14.5

15.2

16.0

16.8

17.5

18.3

19.0

300.

0014

.315

.216

.016

.817

.718

.519

.320

.121

.040

0.00

15.2

16.1

17.0

17.9

18.8

19.7

20.6

21.5

22.4

500.

0015

.816

.817

.818

.719

.720

.621

.622

.623

.560

0.00

16.3

17.4

18.4

19.4

20.4

21.4

22.4

23.4

24.5

700.

0016

.817

.818

.919

.921

.022

.123

.124

.225

.380

0.00

17.1

18.2

19.3

20.4

21.5

22.6

23.7

24.8

25.9

900.

0017

.418

.519

.720

.822

.023

.124

.325

.426

.6



The formula method may also be employed using one of twoapproaches. The first approach is based on the criterion of achieving a certainminimal center point temperature in the product, for example, 85°C. In thisscenario, the process time can easily be calculated using Equation 12.7. Theparameters fh and jch are obtained from the heat penetration data, and Ti andTR are known. The value for gc is also known because gc = TR − 85°C (usingthe above criterion). A sample calculation to determine the process time toachieve a final temperature (Tc) of 85°C is shown in Table 12.3.

The other approach using the formula method is based on Stumbo’smethod to calculate process time when the required process lethality (withany selected reference temperature, e.g., 85°C, and z value, e.g., 5.6°C) isknown or to calculate process lethality when the process time is given.Calculation examples are shown in Table 12.4 and Table 12.5.

12.4 Canning operationsConsidering variations in the canning process for different types of berryfruits, the following operations are described in general, with reference tospecific fruits whenever appropriate. The flow chart of a typical berry fruitcanning process is shown in Figure 12.5.

Table 12.2 Process Calculation by the Improved General Method (Numerical Integration Technique)

Time(minutes)

Temperature(°C)

Lethal rate (L = 10(T−85)/5.6) L × time interval

0 54 0.000 0.0002 71 0.003 0.0064 82 0.291 0.5826 91 11.79 23.588 85 1.000 2.000

10 71 0.003 0.00612 54 0.000 0.000

F0 = Σ (L × Δt) 26 minutes

Table 12.3 Process Time Calculation Using Ball’s Formula Method

1. fh 16.2 minutes2. jch 1.23. Retort temperature (TR) 100°C4. Initial temperature (Ti) 15°C5. Ih = TR − Ti 85°C6. jchIh 1027. log(jchIh) 2.018. Final temperature (Tc) 85°C9. gc = TR − Tc 15°C10. log (gc) 1.1811. B = fh[log(jchIh) − log(gc)] 13.4 minutes



Table 12.4 Calculation of Process Time Using Stumbo’s Formula Method1. fh 12.3 minutes2. jch 1.123. Retort temperature (TR) 93°C4. Initial temperature (Ti) 15°C5. Ih = TR − Ti 78°C6. jchIh 87.47. log(jchIh) 1.948. Required process lethality (F0) 30 minutes9. z 5.6°C10. Fi = 10[(85−TR)/z] 0.0411. U = F0Fi 1.2 minutes12. fh/U 10.313. jcc 1.614. From Stumbo’s table, for z = 5.6°C, jcc = 1.6, obtain gc value by

interpolationfh/U gc (°F)10 5.4420 7.91

Interpolate10.3 5.51

5.51°F temperature difference corresponds to 3.06°C temperature difference

15. log(gc) 0.4916. B = fh[log(jchIh) − log(gc)] 17.8 minutes

Table 12.5 Calculation of Process Lethality Using Stumbo’s Formula Method1. fh 16 minutes2. jch 1.363. Retort temperature (TR) 93°C4. Initial temperature (Ti) 20°C5. Ih = TR − Ti 73°C6. jchIh 99.37. log(jchIh) 2.008. Process time (B) 20 minutes9. z 5.6°C10. Fi = 10[(85−TR)/z] 0.0411. B/fh 1.2512. log(gc) = log(jchIh) − B/fh 0.7513. gc 5.62°C14. jcc 1.815. From Stumbo’s table, for z = 5.6°C, jcc = 1.8, obtain fh/U by interpolation

5.62°C temperature difference corresponds to 10.1°F temperature differencegc fh/U10 3011.2 40

Interpolate10.1 30.8

16. U = fh/(fh/U) 0.5217. F0 = U/Fi 13 minutes



12.4.1 Raw material selection

The quality of processed fruit depends largely on the quality of the raw fruit,and this in turn depends on how the fruit is harvested, handled, and stored.26

Harvesting at the proper maturity is an important step in the thermal pro-cessing of berry fruits. Practically all berry fruits are harvested in the“firm-ripe” stage, when they have attained the desired shape and size, andare still firm enough to withstand reasonable handling without bruising.

In the “mellow-ripe” stage, most berries are in prime condition forconsuming. Therefore most berry fruits are canned in the “mellow-ripe”stage to capture maximum natural nutrients, flavor, aroma, and color. A fewberry fruits, such as black currants and gooseberries, are canned in the“firm-ripe” stage. In such cases, different ingredients may be added, suchas spices, salt, sugar, calcium, colors, flavors, and nutrients (e.g., vitamin C),to compensate for the underdeveloped full natural flavor and aroma. Berriesthat are used to produce juices, purees, preserves, marmalades, and saucesare processed in the “soft-ripe” stage because flavor and aroma are moreimportant than texture.26

12.4.2 Washing

Berries are washed with water to remove dust, dirt, insect frass, mold spores,and plant parts that will affect their color, aroma, and flavor. This processshould be carried out thoroughly to ensure the removal of the heat-resistantmicromycete Neosartorya fischeri, which has been linked to mold formationin canned fruits.27 In addition, the water is also used to cool the produce byremoving field heat following harvesting.

The volume of water required varies with the method of preparation forcanning and the kind of the berry fruit.2 Detergents are frequently used inthe wash or rinse water. The water temperature should be kept low becauseit will keep the fruit firm and reduce leaching. The effectiveness of thewashing operation depends on the amount, temperature, acidity, hardness,and mineral content of the water and the force at which it is applied.26

Figure 12.5 Typical berry fruit canning operations.

Raw material

Sealing Exhausting

Washing

Cooling Labeling

Sorting/grading

Filling

Storage

Thermalprocessing



12.4.3 Sorting/grading

This operation ensures the removal of inferior and damaged produce. Aninspection belt may be used in addition to trained personnel who detectpoor-quality produce unsuitable for canning. Sorting labor costs may bereduced by new technologies that are noninvasive, such as magnetic reso-nance imaging.28 Considerable recent research has been focused on usingoptical techniques to measure the internal quality of fruit. Near-infraredspectroscopy (NIRS), which measures diffusely reflected or transmitted lightover a range of invisible wavelengths longer than visible light, has been usedfor predicting the sweetness of fresh fruits. Commercial application of NIRSfor sorting apples and other fruits for sweetness has started recently. How-ever, there are still considerable technological challenges for measuring firm-ness and other quality attributes of fresh fruit.29

Acceptable fruits are then size sorted, where they are mechanicallypassed over a screen with different size holes or slits. Undersized fruit issorted out and used as concentrate or for jam manufacture.28 Fruits withaesthetic defects may be used for juices and concentrates.

12.4.4 Filling

Can filling is usually done by automatic machines, although it may be doneby hand for very soft fruits that have a tendency to bruise easily. Mechanicalfillers are adjusted to dispense each can a predetermined volume of fruitfrom a chamber and add a given amount of syrup or water. These quantitiesmust be uniform in order to ensure accurate and constant fill weights, whichis desirable not only for economic reasons, but is also technically important.

Most berry fruit products require a headspace in the can, especiallythose that are processed in an agitating retort. The headspace bubble in thecan is crucial for movement of the contents during agitation. The amount ofheadspace in a can is important; insufficient space may cause the can endsto bulge, whereas excessive space can cause under processing and evencollapse of cans during processing, as well as lead to can corrosion duringstorage due to insufficient vacuum.

12.4.4.1 Type of packBerry fruits are available for canning mostly in the form of whole fruit aswell as in other forms such as sauce, puree, juice, or in mixed fruit packssuch as fruit cocktail.

12.4.4.2 Type of covering liquidDuring thermal processing of canned berries, heat is first transferred fromthe heating medium (steam or water) to the container surface and then tothe covering liquid. The covering liquid may include syrup, water, mixturesof fruit juices and water, or fruit juices alone. Heat from the covering liquidis then transferred to the fruit itself. Besides facilitating heat transfer to the



fruit, the covering media also serves to sweeten the product and improvethe quality characteristics (aroma and color), as well as to fortify the nutri-ents. The most common syrups in canned berry products are sucrose syrup(cane or beet sugar), corn syrup, invert sugar syrup, dextrose, and highfructose corn syrup.2 The different designations for syrups range from lightfruit juice syrups to extra heavy syrups. Their designations followed by their°Brix measurement are extra heavy syrup (E), 22° to 35°; heavy syrup (H),18° to 22°; light syrup (L), 14° to 18°; and light fruit juice syrup or water (W),less than 14°.2 Another option is canning in natural fruit juices.30 Syrupstrengths can be verified using a refractometer or a Brix hydrometer. Recentmarket trends, however, have found a growing popularity toward packingin concentrated juice of the same fruit with no sugar added.28 According toCanadian labeling standards, when fruits are packed without sugar the labelmay indicate “no sugar added” or “unsweetened.”

12.4.4.3 Container specifications and typesIn the United States, Canada, and a majority of other countries, can dimen-sions are expressed using two numbers, each number consisting of threedigits. The first of both numbers refers to whole inches, and the second andthird digits together refer to the additional fraction of the dimensionexpressed in sixteenths of an inch. The first three-digit number refers to thecan diameter and the second three-digit number refers to the can height. Forexample, a can with the dimensions 401 × 411 would be 4 1/16 inches indiameter (from the outside edge of both double seams) and 4 11/16 inchesin height (the outside edge of both terminal seams).

Specifications for dimensions of glass containers are similar to cans,except that specific numbers for jars are assigned to the equivalent candimensions. Glass containers are frequently used for products such as berryfruits. Three numbers are used for rectangular cans to denote the dimensionsof length, width, and height, respectively.

In addition to the traditional can, which is recyclable, but costly withrespect to its requirements for tin, steel, and aluminum, other types of con-tainers are competing for an advantage in the processed fruit industry. Plastic-ring six-pack carriers for beverages, thinner wall metal cans, and paper-basedcomposites (e.g., paper, plastic, and metal foil laminates) have been and willundoubtedly be used on a larger scale in the future due to current concernsfor convenience, cost, and environmental issues.28

12.4.4.4 Container sizesIn the California canned fruit industry, the most popular consumer sizes arethe buffet (8 oz.), the no. 303 (16 oz.), and the no. 2 1/2 (l lb. 13 oz.). Cannedfruits in Canada are usually packed in standard sizes of 5 fl. oz. (142 ml), 10fl. oz. (284 ml), 14 fl. oz. (398 ml), 19 fl. oz. (540 ml), 28 fl oz. (796 ml), 48 floz. (1.36 l), and 100 fl. oz. (2.84 l).

For information on “Suggested New Quantity Statements for Fruits,” refer tothe Almanac of the Canning, Freezing, Preserving Industries.31 Suggested container



sizes are listed for a variety of canned fruits with different levels of syrup(from light to extra heavy), along with the imperial and metric measures fornet capacity. A table with label measurements for various can sizes is alsoincluded, with the common name of the can, the can size from 202 × 204 to603 × 700, and label sizes.

12.4.4.5 Can lacquerAs high-acid and highly colored fruits, most berries require an acid-resistantlacquer. Cans for jams made from these fruits also require a lacquer. Goose-berry fruit is an exception, which can be packed in plain-bodied cans.

Two kinds of lacquered cans are available: an acid-resisting (AR) lacquer(for acid foods, mostly fruits) and a sulfur-resisting (SR) lacquer (for low-acidfoods such as vegetables, beans, and meat). The “R” enamel protects thenatural pigment of highly colored fruits such as dark-colored berries.2

12.4.5 Exhausting and vacuum

The primary reason for exhausting and vacuum is to create an anaerobicenvironment in the can that inhibits microbial spoilage. Vacuum treatmentalso removes occluded gases from fruit tissue, which is necessary in orderto increase its specific gravity. Generally three methods of can exhaustingare used in order to remove headspace gas and produce a vacuum.

The conventional technique is thermal exhausting, which involves thepassage of cans through a steam chamber or exhaust box. The steam replacesthe air inside the can and it is sealed while still hot. The vacuum is createdin the can following condensation of the steam. This process is very energyintensive because of the excessive steam requirements.

Another available method is “steam-flow” or “steam-vac” closing, wherehigh-pressure steam is injected into the can headspace just prior to closing(approximately 5 to 8 minutes at 100°C).28 Thus all of the air is quicklyreplaced with steam, which will condense and form a vacuum followingseaming. Steam-flow closing is relatively efficient, less energy intensive, andless expensive than thermal exhausting.

High-speed mechanical vacuum sealing is also commonly used. In thismethod, cans filled cold with fruit and syrup are passed into a clincher thatclinches the cans (first operation roll seam) but does not form an airtight seal.The cans are then subjected to a vacuum for only a short period of time. Thispractice removes the free headspace air, but not all dissolved gases within theproduct. An advantage of this method is that it eliminates the need for exhaust-ing of cans as a separate unit operation and saves processing space. Vacuumcan-closing machines may pose potential problems for fruits packed in syrup.Because of the excess liquid in the can, the vacuum applied may draw someof the liquid out of the can. In order to prevent such loss of liquid, a prevacuumstep before vacuum closing is employed, where a vacuum is drawn first onfruit alone in the can, and then, while still under vacuum, the syrup is added.2The filled cans are then subjected to the vacuum sealer with practically nodissolved air in the can and no subsequent loss of syrup.



12.4.6 Seaming/closing

The can should be closed immediately after filling and exhausting to preventexcessive cooling of the surface of the product. Modern can seamingmachines operate at speeds as high as 300 cans/min. Liquid products maybe sealed in cans at speeds of up to 1600 cans/min.2 The double-seamingoperation is critical to ensure a hermetic seal and good quality of the finalproduct during storage. Faulty seaming can result in deformations in thecan during processing and eventually recontamination. Glass jars are closedwith a screw cap.

12.4.7 Container coding

All containers should be coded for recall purposes in case of problems inthe stored product, such as spoilage, contamination, or consumer complaints.The code should provide necessary information such as the canning plantwhere packed; the day, year, and hour packed; the packing period; and theline on which the product was packed.2 This practice should be carefullyfollowed, along with the filing of adequate production and shipping records.

12.4.8 Retort operations

The simplest pasteurization equipment is a water bath maintained at anappropriately high temperature.32 Full crates containing berries packed insyrup or water are placed in steam-heated water in large steel tanks. Afterthe required processing time, cold water is added to the tank for cooling orthe crates are lifted out and immersed in a cold water tank for cooling.

Continuous water bath pasteurizers consist of a long tank through whichcans move along on a belt. Alternately, the containers can travel through atunnel along a conveyor belt and are subjected to continuous water sprays.As they travel, the cans pass through several temperature zones from pre-heating and pasteurization to the final cool. In the pasteurization section,steam (100°C) at atmospheric pressure is sometimes injected for quickerheating. The moderated temperatures that are possible in these systemsmake them ideal pasteurizers for berry products in glass jars that are sensi-tive to thermal shocks.

Another type of unit that is used for pasteurization of berry products isthe continuous agitating atmospheric cooker.32 Its operation is similar to thatof more conventional high-pressure continuous cookers, but the operationis limited to atmospheric pressure to accomplish pasteurization. These agi-tation processes are used to uniformly cook products throughout the con-tainer. Product agitation is also possible in batch-type rotary retorts, in whichcans are often subjected to end-over-end agitation.

Aseptic or ultra-high temperature (UHT) processing has become a suc-cess story for fruit beverages, purees, and juices containing small particles.In this process, the food and the packaging material are sterilized separatelyand then assembled under sterile conditions. The product is first subjected



to heat by passing the liquid product through a shell and tube or plate heatexchanger and held for sufficient time in holding tubes to complete therequired pasteurization treatment. Following the required treatment, theproduct is then passed through another heat exchanger where it is cooled.The filling and sealing operations are then performed in presterilized con-tainers (laminated cartons) under aseptic conditions. Plate-type indirect heatexchangers are extensively used for such purposes. The juice flows throughone side of a wall while the heating medium (steam or hot water) flows onthe other side. The plate is designed in such a way that it yields extremelyhigh rates of heat transfer. Tubular heat exchangers are also available forpasteurization purposes. For more viscous products such as cream, yogurt,and salad dressing, and for products containing small particulate matter,scraped surface heat exchangers are used to prevent surface fouling prob-lems and promote rapid heat transfer.

Because the packaging material must be sterilized prior to filling, thematerial should possess physical properties that permit this application aswell as that of hermetic sealing. One type of composite package that is exten-sively used as a packaging material for aseptic processing is a paperboard-foil-plastic laminate known as “Tetra-Pak.” This type of package consists ofa series of six layers of materials, with polypropylene as the outermost layer,followed by “Surlyn” aluminum foil, polyethylene, paperboard, and polyeth-ylene again as the innermost layer. Polypropylene and polyethylene act asheat-sealing surfaces, whereas aluminum foil acts as a barrier material thatis protected from mechanical damage by the paperboard. This compositepackage acts as a barrier to oxygen, light, moisture, and microorganisms, andit meets all of the requirements necessary for successful application of theaseptic process, including heat sealability and strength. Prior to filling, acommon sterilization method for this packaging material is the use of hydro-gen peroxide in combination with heat or ultraviolet radiation treatment.

For maximum nutrient retention, HTST pasteurization methods are oftenrecommended if heat resistant enzymes such as peroxidase or pectin esteraseare not present in the product. This is because increases in processing tem-peratures will cause faster destruction rates for microbial population ascompared to nutrients. The presence of heat resistant enzymes, which havea higher heat tolerance than microorganisms, do not always permit fruits,for example, to be subjected to such a process.

12.4.9 Cooling

After thermal processing, the contents of the can should be cooled to anaverage temperature of about 35°C to 40°C.33 Storage at higher temperatureswill cause loss of color and darkening or pink discoloration (stack burn). Ifcans are cooled too far below the average temperature, they will remain wetand rusting may result due to insufficient surface drying. Water used forcooling should be noncorrosive, low in bacterial and yeast content, andchlorinated for measurable free-chlorine residual detected at the discharge



end of the cooler. The cooling water should also be chlorinated with 2 ppmof available chlorine to prevent infection of the can contents with spoilagemicroorganisms.

12.4.10 Labeling and storage

Following cooling, cans are labeled for identification purposes. Adequatelyprocessed cans usually ensure acceptable canned fruit quality on the retailmarket for at least 1 year. Storage temperature has been found to be the mostimportant variable in the maintenance of an acceptable product with mini-mal flavor, color, texture, and nutritive changes. Common storage tempera-tures for canned berries seldom average above 21°C.1 Above 27°C, gradualsoftening occurs. Freezing causes greater changes and canned berries shouldnot be allowed to freeze. Freezing can cause distortion of the can seams andmay eventually lead to microbial spoilage. The most important cause ofquality deterioration in canned fruit is very slow chemical changes that takeplace during storage, resulting in changes in nutritive value, flavor, color,and texture. However, based on estimated kinetic parameters for modelingquality changes, it may be possible to predict color degradation of juices orother liquid foods during processing.34

12.5 Grades of canned berriesMost heat-processed fruits in Canada are sold by grade. The standards areestablished by the Processed Fruit and Vegetable Regulations of the CanadaAgricultural Products Standards Act. The products are graded on a varietyof quality factors such as flavor and aroma, tenderness and maturity, color,consistency of texture, appearance of the packing media, uniformity of sizeand shape, and freedom from defects and foreign matter.35

There are three general grades: Canada Fancy, Canada Choice, and CanadaStandard. Canada Fancy fruits are free from blemishes, clean, and of goodcolor and uniform size. Canada Choice fruits have slight variations in size,color, and maturity, but are almost completely free of blemishes. CanadaStandard fruits are mainly used for sauces and puddings because they maybe broken and more or less ripe. The appropriate grade must appear on themain part of the label.

The U.S. grade standards for fresh and processed fruits are under thejurisdiction of the U.S. Department of Agriculture (USDA) Food Safety andQuality Service (FSQS). The USDA provides an inspection service to certifythe quality of processed fruits based on U.S. grade standards. The inspectionservice is voluntary and paid for by the user. Under the program, processedfruits are inspected by highly trained specialists during all phases of prep-aration, processing, and packaging.

Many processors and wholesalers use the USDA grade standards toestablish the value of their product described by the grades. Manufacturersand packers frequently employ them in quality control work.



The standards for grades usually vary for each commodity. The gradestandards for canned berry fruits can be found in 7 CRF 52 Section 551(Blackberries, and other similar berries, canned), Section 581 (Blueberries,canned) and Section 3311 (Raspberries, canned). The U.S. grades include thefollowing: U.S. Grade A (U.S. Fancy), U.S. Grade B (U.S. Choice), U.S. GradeC (U.S. Standard), and U.S. Grade D (U.S. Substandard).

Grade A fruits are the very best, free from defects, with similar varietalcharacteristics, good color, uniformity in size, good character, normal flavor,and score not less than 90 points when scored in accordance with the associatedscoring system. Having the proper ripeness and few or no blemishes, fruitsof this grade are excellent for special purpose use where appearance and flavorare important. They are excellent for special luncheons or dinners, served asdessert, used in fruit plates, or broiled or baked to serve with meat entrees.

U.S. Grade B fruits make up much of the fruit that is processed and are ofgood quality. Only slightly less perfect than Grade A in color, uniformity, andtexture, they score not less than 80 points when scored in accordance with theassociated scoring system. Grade B fruits have good flavor and are suitable formost uses: as breakfast fruits, in fruit cups, toppings for ice cream, or as side dishes.

U.S. Grade C fruits may contain some broken and uneven pieces. Theyscore not less than 70 points when scored in accordance with the associatedscoring system. While the flavor may not be as sweet as in higher qualities, thesefruits are still good and wholesome. They are useful where color and textureare not of great importance, such as in puddings, jams, and frozen desserts.

U.S. Grade D fruits are those whose quality fails to meet the requirementsof U.S. Grade C. The scoring system for grading is different for differentberry fruits. Table 12.6 shows the score points of factors for canned black-berries and other similar berries.

12.6 Canning of berry fruit12.6.1 Blackberry

Cultivated blackberries are used for processing. In California, the principalcultivar is the boysenberry. Blackberries should be harvested in shallowboxes to prevent crushing. They should be picked just before becoming soft

Table 12.6 Score Points of Factors for Different Grades of Canned Blackberries and Other Similar Berries

Factors Points Grade A Grade B Grade C Grade D

Color 20 18–20 16–17 14–15 ≤13Uniformity of size 20 18–20 16–17 14–15 ≤13Absence of defects 30 27–30 24–26 21–23 ≤20Character of fruits 30 27–30 24–26 21–23 ≤20Total score 100 ≥90 ≥80 ≥70 <70

Source: USDA.



so that they will remain in good condition and will not soften too much inprocessing.2 If possible, they should be canned on the same day they arepicked, otherwise serious deterioration may occur.36

Blackberries are sorted on an inspection belt and then washed thor-oughly in a flood washer and sprayed with clean water as they emerge onan inclined belt. They are then packed in lacquered cans filled with wateror light syrup for pie making or heavy syrup for dessert purposes. No matterwhether water or syrup is used, it should be added to the can at or near theboiling temperature. The cans should then be given a short exhaust andsealed. If a steam flow closing machine is used, the syrup filling temperaturecan be 82°C or higher. The sealed cans are processed in boiling water toattain a center can temperature of 85°C. The cans should then be well cooledbefore stacking or casing.

12.6.2 Blueberry

The highbush cultivars are handpicked, while the lowbush cultivars arepicked by raking. After harvesting, blueberries are cleaned mechanicallyin the field through a fanning mill, which removes leaves, twigs, stems,and other light trash using blasts of air. Following this, the berries arewashed either in a shaker washer or paddle washer. They are then sortedon a convey belt. The sorted blueberries are packed in lacquered cans andcovered with boiling water for pie making or boiling syrup for dessertfruits. Wild blueberries packed in no. 2 or smaller cans need not beexhausted when a mechanical vacuum or steam flow closing machine isused. Cultivated blueberries should be exhausted regardless of the closuremethod used, since they are more corrosive than the wild species.2 All no.10 cans should be exhausted and seamed with a steam flow closing machineto get sufficient vacuum for satisfactory storage life. The sealed cans areprocessed in boiling water to raise temperature in the center of the can to85°C. Blueberries are available in various forms, from a highly attractive,free-flowing product to one that is clumped into a firm mass. Clumpingcan be greatly reduced by agitation during cooling. Overcooking also con-tributes to clumping.36

12.6.3 Black currant

Only firm, ripe black currants should be used for canning. The most suitablecultivar is probably Baldwin. Harvesting and strigging black currants is laborintensive. Commercially, mechanical strigging is used to pull the stem froma hard frozen currant.37 After leaving the strigging machine, the currants areinspected on a slow-moving belt to remove split or broken berries. Thecurrants are then packed in lacquered cans that are filled with syrup. Thefilled cans are exhausted to reach a can center temperature of 82°C, sealed,and processed in boiling water. Black currants are also processed into puree,syrup, and juice.



12.6.4 Cranberry

Cranberries ripen in the fall and can be picked by hand or by a machineusing air suction to strip the berries. Popular canned cranberry products arestrained (jelly-like) and unstrained (whole berry) sauce.2 Whole cranberrysauce is prepared by cooking the berries with water in a steam-jacketed kettleand adding sugar. The berries must first be cleaned to remove all stems. Thesurface of the cranberry must be roughened slightly. The berries may beadded to already heated water in the kettle and are cooked for 8 to 10 minutes.Sugar, another sweetener, or a blend of sweeteners is added after the berriesare well cooked, the quantity being determined by the product desired.Usually about the same weight of sugar is added as the weight of raw berries.The finish is determined by cooking to a definite temperature, which isgenerally 102°C or by the percentage of solids, as determined by a refractometer.It has been found that cooking equal weights of berries, water, and sugar toa temperature of 102°C gives a satisfactory product with about 43% totalsugar content as determined by refractometer. Whole cranberry sauce shouldnot be cooked to a solid gel, but should flow slowly when poured into adish. Care should be taken in handling berries for whole sauce to preventexcessive crushing, especially while they are being stirred.

To prepare strained cranberry sauce, all the stems must be removed andthe berries placed directly into kettles of water. The berries are then heated 8to 10 minutes and run through a cyclone to remove the skins and seeds. Thescreens should be sufficiently fine to remove most seeds, a suitable openingsize being 0.03 to 0.04 inch. The pump from the cyclone passes to anothersteam-jacketed kettle, where the sugar is added. Evaporation is determinedby thermometer, refractometer, or by appearance or consistency when the gelpoint is reached. The weight of sugar added is approximately equal to theinitial weight of the berries. The gel point is usually reached when the sauceis heated to about 102.8°C and has a total solid of approximately 43%.

The sauce is filled into lacquered cans at a temperature of at least 82°C. Thecans should be completely full at the closing machine, leaving no headspace, toprevent air from darkening the sauce. No process is necessary and the cans passdirectly to the cooler, where they should be cooled to 35°C to 40°C.

12.6.5 Gooseberry

Most fruits lose their flavor when canned, but gooseberries improve theirflavors.37 The most important cultivars are Careless and Keepsake. Goose-berries are canned when they reach full size, but before they become soft orshow a color change.

Gooseberries pass through a cleaning machine to remove the leaves andother light vegetable materials by air flow. Then they go through a snipperto remove the stalks and blossom ends. The gooseberries are then sorted ona slow-moving belt. The fruits are washed, drained, and filled into plaincans. The bulk of gooseberries are packed in water in no. 10 cans for thebakery trade and a few are packed in heavy syrup in no. 2 or no. 303 cans



for table use.2 After filling the cans, boiling water or boiling syrup is addedand the cans are exhausted in a steam box, sealed under steam injection, andprocessed in boiling water.

12.6.6 Loganberry

Loganberries have a very large size and a deep red color. They are mostly usedfor pie making and thus are canned in lacquered cans in water. The processesof harvesting, canning, and sterilizing are basically the same as for blackberries.36

12.6.7 Raspberry

Raspberries are picked when they are ripe, but firm. They should never becanned after they become soft, otherwise they will break down completelyin the container. They are transported to the cannery in small shallow pun-nets to avoid crushing. They should be kept in a refrigerated room at 1°Cto 4°C and should be canned promptly when they arrive at the cannery.37

The berries are washed and sorted to remove deformed and overripeberries. They are gently filled into fully lacquered cans and then hot water orsyrup is added. If syrup is used, its temperature should be at least 93°C. Whenwater is used it should be added at the boiling point. The cans are exhaustedby passing them through a hot water or steam exhaust box to reach a centercan temperature of 74°C to 77°C for no. 2 cans and 71°C for no. 10 cans. Cansare closed in a steam flow closing machine and processed in boiling water toreach a temperature of 82°C to 88°C at the center of the can.

12.6.8 Strawberry

The color and texture of strawberries deteriorate considerably during the can-ning process, and food coloring is not permitted by the FDA. This makes frozenstrawberries more popular in the United States, as they have a more attractivecolor and texture. Canned strawberries are more common in the United King-dom, where the addition of artificial color is permitted. Developing new straw-berry cultivars with more resistance to heat processing is promising.

Strawberries are delivered to the cannery in shallow trays or punnets toprevent crushing. They are first delivered to the preparation belt for stem-ming. Grading is necessary so berries are of a uniform size; this can beaccomplished with a mechanical grader. The berries are given a light spraywashing to remove soil, straw, and leaves, especially following a rain.Washed berries are filled into fully lacquered cans and covered with syrup.Before sealing, the cans must be thoroughly exhausted to collapse the berriesslowly and release oxygen from their cells. If the exhaust is insufficient, theberries will collapse during cooking, with the result that the vacuum in thecontainer will not be maintained and the berries will spoil quickly.36 Sealedcans are processed in boiling water.

Table 12.7 lists typical conditions for processing selected berries in boil-ing water.



Tabl

e 12

.7Ty

pica

l Con

dit

ions

for

Pro

cess

ing

of B

erri

es in

Boi

ling

Wat

er

Fru

it

Typ

e of

can

Filli

ng

tem

per

atu

re

(°C

)

Exh

aust

tim

e (m

inu

tes)

Pro

cess

tim

e (m

inu

tes)

Cov

erin

g liq

uid

cE

nam

el c

oati

nga

Stee

lbC

an s

ize

Can

siz

eB

ody

En

ds

No.

2N

o. 1

0N

o. 2

No.

10

Bla

ckbe

rry

E*

EL

824–

56–

1015

23–2

7E

, H, L

, WB

lueb

erry

E*

EE

L82

E, H

, L, W

Wild

and

nor

ther

n cu

ltiv

ated

spe

cies

4–6

8–12

1020

–25

Sout

hern

cul

tiva

ted

sp

ecie

s10

18–2

03–

45–

10

Bla

ck c

urra

nts

E82

8–12

Cra

nber

ry s

auce

E*

82G

oose

berr

yP

10W

15H

, W15

–20H

Ras

pber

ryE

*E

L82

10L

23W

E, H

, L, W

15H

28L

Stra

wbe

rry

E*

EL

825–

87–

1410

E, H

, L, W

a E

, sin

gle-

coat

ena

mel

; EE

, dou

ble-

coat

ena

mel

; E*,

wit

h in

sid

e se

am s

trip

of

enam

el; P

, pla

in.

b L

, use

d f

or s

tron

gly

corr

osiv

e fr

uits

.c E

, ext

ra h

eavy

syr

up; H

, hea

vy s

yrup

; L, l

ight

syr

up; W

, wat

er.

Sour

ces:

Woo

dro

of a

nd L

uh1

and

Lop

ez2 .



NomenclatureB Thermal process time; Ball process time (BB) corrected for come-up

period (steam on to steam off −0.6l).fc Cooling rate index. It is the time required for the straight-line portion

of the cooling curve to pass through one complete log cycle. It is alsothe negative reciprocal of the cooling rate curve.

fh Heating rate index. It is the time required for the straight-line portionof the heating curve (Figure 12.5) to pass through one complete logcycle. It is also the negative reciprocal of the heating rate curve.

gc The difference between the retort temperature and food temperatureat the end of the heating or beginning of the cooling period (TR − Tic).

Ic The difference between the cooling water temperature and food tem-perature at the start of the cooling process (Tic − Tw).

Ih The difference between the retort temperature and food temperatureat the start of the heating process (TR − Tih).

jcc Cooling rate lag factor; a factor, which when multiplied by Ic locatesthe intersection of the extension of the straight-line portion of thesemilog cooling curve and the vertical line representing the start ofthe cooling process; jcc = (Tw − Tpic)/(Tw − Tic).

jch Heating rate lag factor; a factor, which when multiplied by Ih locatesthe intersection of the extension of the straight-line portion of thesemilog heating curve and the vertical line representing the effectivebeginning of the process; jch = (TR − Tpih)/(TR − Tih).

l Come-up period. In batch processing operations, the retort requiressome time to reach the operating condition. The time from steam onto when the retort reaches TR is called the come-up period.0.6l Effective beginning of the process. The retort come-up periodvaries from one process to another and from one retort to another.In process evaluation procedures, about 40% of this come-up periodis generally considered the time at retort temperature because theproduct temperature increases even during this period. In order toaccommodate this, the effective beginning of the process is movedleft a distance 0.4l from the time the retort reaches TR or is movedright 0.6l from steam on.

Pt Operator’s process time (the time after the come-up period; Pt = B − 0.4l).Tic Initial food temperature at the start of the cooling period.Tih Initial food temperature at the start of the heating period.Tpic Pseudo-initial temperature during cooling; the temperature indicated

by the intersection of the extension of the cooling curve and thevertical line representing the start of cooling.

Tpih Pseudo-initial temperature during heating; the temperature indicatedby the intersection of the extension of the heating curve and thevertical line representing the effective beginning of the process (0.6l).

TR Retort temperature.Tw Cooling water temperature.



References1. Woodroof, J.G. and Luh, B.S., Commercial Fruit Processing, 2nd ed., Avi Pub-

lishing, Westport, CT, 1986.2. Lopez, A., A Complete Course in Canning and Related Processes, 12th ed., CTI

Publications, Baltimore, MD, 1987.3. Ball, C.O., Thermal Process Time for Canned Food, Bulletin 37, Vol. 7, Part 1,

National Research Council, Washington, DC, 1923.4. Pflug, I.J., Evaluating the lethality of heat processes using a method employ-

ing Hick’s table, Food Technol., 33, 1153, 1968.5. Hayakawa, K., A procedure for calculating the sterilization value of a thermal

process, Food Technol., 22, 905, 1968.6. Hayakawa, K., Mathematical methods for estimating proper thermal processes

and their computer implementation, Adv. Food Res., 23, 75, 1977.7. Teixeira, A.A., Dixon, J.R., Zahradnik, J.W., and Zinsmeister, G.E., Computer

optimization of nutrient retention in the thermal processing of conduction-heated foods, Food Technol., 23, 845, 1969.

8. Griffin, R.C., Jr., Herndo, D.H., and Ball, C.O., Use of computer-derived tablesto calculate sterilizing processes for package foods. 2. Application to broken-line heating curves, Food Technol., 23, 519, 1969.

9. Griffin, R.C., Jr., Herndo, D.H., and Ball, C.O., Use of computer-derived tablesto calculate sterilizing processes for package foods. 3. Application to coolingcurves, Food Technol., 25, 134, 1969.

10. Manson, J.E., Zahradnik, J.W., and Stumbo, C.R., Evaluation of lethality andnutrient retentions of conduction-heating foods in rectangular containers,Food Technol., 24, 1297, 1970.

11. Tung, M.A. and Garland, T.D., Computer calculation of thermal processes, J. FoodSci., 43, 365, 1979.

12. Ramaswamy, H.S., Lo, K.V., and Tung, M.A., Simplified equations for tran-sient temperatures in conductive foods with convective heat transfer at thesurface, J. Food Sci., 47, 2042, 1982.

13. Pham, Q.T., Calculation of thermal process lethality for conduction-heatedcanned foods, J. Food Sci., 52, 967, 1987.

14. Ramaswamy, H.S. and Marcotte, M., Food Processing Principles and Applications,1st ed., CRC Press, Boca Raton, FL, 2005.

15. Alzamora, S.M., Tapia, M.S., Argaíz, A., and Welti, J., Application of combinedmethods technology in minimally processed fruits, Food Res. Int., 26, 125, 1993.

16. Fellow, P., Food Processing Technology: Principles and Practices, Ellis Horwood,Chichester, UK, 1988.

17. Ramaswamy, H.S. and Abdelrahim, K., Thermal processing and computermodeling, in Encyclopedia of Food Science and Technology, Hui, Y.H., Ed., Wiley,New York, 1991, p. 2538.

18. Ramaswamy, H. S. and Abbatemarco, C., Thermal processing of fruits, inProcessing of Fruits—Science and Technology, Vol. 1, Biology, Principles, andApplications, Somogyi, L.P., Ramaswamy, H.S., and Hui, Y.H., Eds., TechnomicPublishing, Lancaster, PA, 1996.

19. Ranganna, S., Handbook of Analysis and Quality Control for Fruit and VegetableProducts, McGraw-Hill, New Delhi, India, 1986.

20. Kyzlink, V., Principles of Food Preservation, Elsevier Science, New York, 1990.21. Desrosier, N.W., Elements of Food Technology, Avi Publishing, Westport, CT, 1977.



22. Stumbo, C.R., Thermobacteriology in Food Processing, 2nd ed., Academic Press,Orlando, FL, 1973.

23. Ball, C.O. and Olson, F.C.W., Sterilization in Food Technology, McGraw-Hill,New York, 1957.

24. Holdsworth, S.D., Thermal Processing of Packaged Foods, 1st ed., Chapman &Hall, London, 1997.

25. Stumbo, C.R. and Longley, R.E., New parameters for process calculation, FoodTechnol., 20, 341, 1966.

26. Prussia, S.E. and Woodroof, J.G., Harvesting, handling and holding fruit, inCommercial Fruit Processing, 2nd ed., Avi Publishing, Westport, CT, 1986, chap. 2.

27. Jesenka, A., Pieckova, E., and Septikova, J., Thermoresistant propagules ofNeosartorya fischeri; some ecologic implications, J. Food Prot., 54, 582, 1991.

28. Moulton, K., Maintaining the Competitive Edge in California’s Canned FruitIndustry, University of California–Berkeley, Berkeley, CA, 1992.

29. Lu, R., Apple quality’s more than skin deep, Agric. Res., 53, 8, 2005.30. Vyas, K.K. and Joshi, V.K., Canning of fruits in natural fruit juices. I. Canning

of peaches in apple juice, J. Food Sci. Technol., 18, 39, 1981.31. Almanac of the Canning, Freezing, Preserving Industries, Vols. 1 and 2, Edward

E. Judge & Sons, Westminster, MD, 1993.32. Lund, D.B., Heat processing, in Principles of Food Science, Part II. Physical

Principles of Food Preservation, Fennema, O.R. and Lund, D.B., Eds., MarcelDekker, New York, 1975.

33. Jackson, J.M, Canning procedures for fruits, in Fundamentals of Food CanningTechnology, Jackson, J.M. and Shinn, B.M., Eds., Avi Publishing, Westport, CT,1979, chap. 7.

34. Cohen, E., Birk, Y., Mannheim, C.H., and Saguy, I.S., Kinetic parameter esti-mation for quality change during continuous thermal processing of grapefruitjuice, J. Food Sci., 59, 155, 1994.

35. Agriculture Canada, Canada’s Food Grades, Publication 1720E, Minister of Sup-ply and Services Canada, Ottawa, Ontario, Canada, 1982.

36. Luh, B.S., Kean, C.E., and Woodroof, J.G., Canning of fruits, in CommercialFruit Processing, 2nd ed., Avi Publishing, Westport, CT, 1986, chap. 6.

37. Arthey, D. and Ashurst, P.R., Food Processing: Nutrition, Products, and QualityManagement, 2nd ed., Aspen Publishers, Gaithersburg, MD, 2001.



367

chapter 13

Berry jams and jellies


Contents

13.1 Introduction ............................................................................................... 36813.2 Principles of jam and jelly processing................................................... 370

13.2.1 Essential ingredients in jams and jellies................................... 37013.2.2 Sugar concentration and water activity control...................... 37013.2.3 Sugar concentration and microbial growth ............................. 37113.2.4 Sugar infusion as pretreatment and preconcentration .......... 37213.2.5 Pectin .............................................................................................. 37213.2.6 Acid ................................................................................................ 373

13.3 Common procedures for making berry jams and jellies.................... 37313.3.1 Fruit and sugar preparation ....................................................... 37413.3.2 Jam and jelly manufacture.......................................................... 375

13.3.2.1 Jams.................................................................................. 37513.3.2.2 Jellies ................................................................................ 377

13.4 Innovation in berry jam and jelly processing ...................................... 37913.4.1 Low-sugar jam and jelly manufacture...................................... 37913.4.2 Low pressure and low temperature process ........................... 382

13.5 Critical quality and safety factors .......................................................... 38313.5.1 Quality factors .............................................................................. 38313.5.2 Nutritional and safety factors .................................................... 38413.5.3 Packaging....................................................................................... 384

13.6 Applications of berry jams and jellies................................................... 38513.6.1 Spreads........................................................................................... 38513.6.2 Pastries and cookies ....................................................................385




13.1 Introduction

Jams and jellies are products made principally from fruits, but they can alsobe made from some vegetable materials, such as sweet potatoes, tomatoes,carrots, and some legumes. The U.S. Code of Federal Regulations (CFR)provides definitions and standards for jams and jellies: 21 CFR 150.140 forfruit jelly, 21 CFR 150.141 for artificially sweetened jellies, 21 CFR 150.160for jams, and 21 CFR 150.161 for artificially sweetened jams. This part alsoincludes definitions and standards for fruit butter.

1

Generally a preserve orjam is a product manufactured with one or a permitted combination of fruitingredients, and one or any combination of some optional ingredients. Fruitingredients should be mature and properly prepared, including fresh, con-centrated, frozen, or canned. The regulations divide the materials that canbe used for this purpose into two groups: Group I: blackberry (other thandewberry), black raspberry, blueberry, boysenberry, cherry, crabapple, dew-berry (other than boysenberry, loganberry, and youngberry), elderberry,grape, grapefruit, huckleberry, loganberry, orange, pineapple, raspberry, redraspberry, rhubarb, strawberry, tangerine, tomato, yellow tomato, andyoungberry; and Group II: most of the less acidic and higher in pecticsubstances including apricot, cranberry, damson, damson plum, fig, goose-berry, greengage, greengage plum, guava, nectarine, peach, pear, plum (otherthan greengage plum and damson plum), quince, red currant, and currant(other than black currant).

Based on the regulations, any combination of two to five of these fruitsmay be used, providing each of them is not less than one-fifth of the weightof the combination, with the exception of pineapple, which may be not lessthan one-tenth of the weight of the combination. It can also be any combi-nation of apple and one to four of these fruits in which the weight of eachis not less than one-fifth the weight of the combination and apple is not morethan one-half the weight of the combination, with the exception of pineapple,which may not be less than one-tenth of the weight of the total combination.Fruit includes all material listed above, and in any combination such fruitsare considered an optional ingredient.

Regulations permit the use of some safe and suitable optional ingredi-ents, including nutritive carbohydrate sweeteners, spices, acidifying agents,and pectin in an amount that compensates for deficiencies in some of thefruit ingredients, buffering agents, preservatives, and antifoam agents, withthe exception of those derived from animal fat. The proportions of fruit andsugar for mixtures containing only fruits from Group I should be 47 partsby weight of fruit to each 55 parts by weight of sugar. In all other cases, themixture should not be less of 45 parts by weight of fruit to each 55 parts byweight of sugar. For fresh fruit, pits and seeds have to be excluded; forconcentrated fruit, weight considers properly prepared fresh fruit to producethe concentrate.

The final soluble solids of the product shall be 65

°

Brix or 65% by weight.Soluble solids are measured by refractometry according to official methods.

1


Chapter 13: Berry jams and jellies 369

Therefore jams are a mixture of fruit—whole, in pieces, or pulped; fresh,concentrated, frozen, or canned—sugar, and other minor ingredients thathelp develop texture because of the formation of a gel between sugars andpectin substances along with fruit and vegetable acidity. Sometimes it isnecessary to add the last two substances because not all fruits and vegetablehave enough acidity or pectin content for gel formation.

2

Jellies, on other hand, according 21 CFR 150.140, are gelled food made of oneor a permitted combination of fruit juice ingredients and one or any combinationof the optional ingredients. Such a mixture is concentrated with or without heat.Volatile flavoring materials from the mixture may be captured during concentra-tion, separated, concentrated, and added back to the mixture at the end of theprocess. Fruit juice used in jelly manufacture is the filtered or strained liquidextracted with or without application of heat and with or without addition ofwater from mature, properly prepared fruits that are fresh, frozen, or canned.

Some of the fruits used for making fruit jellies include apple, apricot,blackberry (other than dewberry), black raspberry, boysenberry, cherry,crabapple, cranberry, damson, damson plum, dewberry (other than boysen-berry, loganberry, and youngberry), fig, gooseberry, grape, grapefruit, green-gage, greengage plum, guava, loganberry, orange, peach, pineapple, plum(other than damson, greengage, and prune), pomegranate, prickly pear,quince, raspberry, red raspberry, red currant, currant (other than black cur-rant), strawberry, and youngberry. The permitted combinations are two tofive of the fruit juice ingredients, the weight of each being not less thanone-fifth of the weight of the combination. Other optional ingredients, suchas mint flavoring and artificial green coloring, are permitted for apple,crabapple, pineapple, or a combination of these fruits. Cinnamon flavoring,other than artificial flavoring, and artificial red coloring may be used if thefruit juice ingredients are extracted from apple or crabapple. The mixtureshall contain not less of 45 parts by weight of the fruit juice ingredients toeach 55 parts by weight of sugar. The final concentration of soluble solids isnot less than of 65% by weight.

1

Therefore jellies are made from fruit juice, pectin substances, sugar, andan organic acid, normally citric acid, to control acidity to obtain the appro-priate pH for gel formation. Jellies should be translucent, with very low orno pulp, forming a continuous and firm gel structure.

Berries are one of the most suitable fruits for processing into jams andjellies because of their quality, acidity, color, normally high pectin content,flavor, and aroma.

2

Evolution of jams and jellies in recent years has been oriented towardlower amounts of added sugar in order to decrease their effect on the gly-cemic index, especially in people who suffer from diabetics. Some nongly-cemic products have been developed using the basic principles of jam andjelly processing, replacing sugar with nonglycemic sweeteners and a greateramount of pectin substances.

Numerous snack products and pastries are prepared with a variety ofjams and jellies, and thus their quality is a very important factor in the quality



of the final products. Jams and jellies are products called intermediate mois-ture foods. They are self-preserved with respect to most bacteria, but shouldbe preserved against molds and yeast. These two types of microorganismshave to be controlled with chemical preservatives or by using a tightly sealedvacuum container and refrigeration after the container is opened. Low sugarcontent means a higher product water activity (

a

w

). Products with less addedsugar normally have to be thermally treated to prevent bacterial growth, aprocess known as “pasteurization.”

13.2 Principles of jam and jelly processing

There are some differences between jams and jellies. Jams are made withwhole, cut, or crushed fruits or vegetables, while jellies are made withstrained fruit juice. The different nature of the materials leads to differentbehaviors in jam and jelly systems. Relationships between the fruit and otheringredients in the product are very important to ensure product quality. Thepresence of invertase in fruit tissue and its action on fruit sugar duringblending will significantly affect gel formation, color, and taste and shouldbe considered in the formulation of the product.

13.2.1 Essential ingredients in jams and jellies

Jams and jellies are products based in texture formation. They are charac-terized by the formation of a special viscous structure in jams and gelformation in jellies, and both properties are developed by the interactionof sugar, pectic substances, and acidity (pH). In jams, the viscosity is theresult of an interaction between sugar and pectin in the presence of a highfiber content. All cell wall materials are present in the product and theeffects of cellulose and hemicellulose molecules do not permit the formationof a continuous gel. In jellies, clarified or strained juices with very lowfiber content are used; hence the relationship between pectin and sugarpermits the formation of a continuous gel structure.

The gel formation and stability are controlled by pH; thus acidity is adeterminant of jam and jelly rheological properties. Almost all berries havean adequate acidity, but sometimes it is necessary to add additional organicacids in order to improve product quality, especially with very ripe fruit.The quality of jams and jellies depends on the equilibrium between the threeessential ingredients. When sugar is lowered or eliminated, pectin or othergelling substances must be included to compensate for the lack of sugar.

13.2.2 Sugar concentration and water activity control

Water activity strongly depends on the concentration of any solute addedto a solution. The sugar content of fruit depends on the fruit species andmaturity. The types and concentrations of sugar are responsible for some ofthe taste in jams and jellies; added sugar, normally sucrose, does not havethe same effect on this important quality factor.



Jam and jellies water activities are in the range of so-called intermediateproducts, 0.80 to 0.85. These products are not self-preserved because thewater activity values are not low enough to control microbial growth orchemical reactions. The principal microbiological problems are molds andyeast, not bacteria. In this case, chemical preservatives such as sorbate andbenzoate salts can be used. If preservatives are not used, water activity canbe complemented by the use of hermetically sealed containers (glass orgas-tight plastic containers) and recommendations of refrigeration once thecontainers are opened.

Table 13.1 shows sugar, moisture content, and water activity related toshelf life for some berry jams. Most jams have a shelf life of 18 to 36 monthswhen they are prepared with sugar. Sugar is a good depressor of wateractivity, and other water binding components in formulated products makean important contribution in decreasing water activity.

3

13.2.3 Sugar concentration and microbial growth

Sugar is the most important water activity depressor in jams and jellies.Normally the total sugar content of jams and jellies is more than 50%; thusthe effect of sugar content on decreasing free water and water activity isvery significant. This effect is responsible for the intermediate moisturebehavior of these products. One of the effects of this osmotic force causedby the decrease in free water is the control of biological processes like bacteriamultiplication and spore formation in molds. If a fruit pulp is heated afterthe sugar content is increased, the effect of temperature will act synergisti-cally on the microorganisms, preventing multiplication, spore formation, andtoxin formation. The final point of a jam, at 65

°

Brix and at normal pressurewill produce at 104

°

C; in a jelly the temperature could be a little higherbecause the concentration is normally two or three points higher. Highconcentrations of sugar added to fruit pulp can also produce some osmoticdehydration of microorganisms, which can affect their biological functions.

The osmotic tolerance of microorganisms depends greatly on the condi-tions of the media, pH, the temperature at which the product is prepared,acid content, some natural inhibitors, and water activity, which are the most

Table 13.1

Sugar, Moisture Content, Water Activity, and Shelf Life of Some Berry

Jams

Product

°

BrixWater

activity

Moisture content

(%)

Shelf life in glass container before

opening (months)

Strawberry jam 65 0.84 29.8 36Raspberry jam 66 0.85 29.3 36Chilean murtilla jam (

Ugni molinae

Turcz)65 0.83 27.8 36

Blueberry jam 65 0.84 29.0 36Nonsugar strawberry jam 67 0.87 30.0 18



important factors affecting the behavior of bacteria, molds, and yeasts. Berriesare normally high in acidity. When they are prepared with a low water activity,microorganisms do not find appropriate conditions to develop.

3

Therefore, ifjams and jellies are manufactured from sound fruits, the probability of micro-organisms developing in the product is very unlikely. Jams and jellies withsoluble solids of 65% or more, mostly sugar, packaged in a sterilized containeror hot packed will be safe until the container is opened. After the container isopened, the condition of the product can be maintained by using refrigerationor by using preservatives such as sorbic or benzoic salts.

3

13.2.4 Sugar infusion as pretreatment and preconcentration

Preparation of fruit for jam and jelly manufacture includes the blending offruit with a portion of the total sugar of the formula; one-third or one-half,for instance. Sugar in contact with whole or cut fruit produces a sort ofosmotic dehydration, with removal of part of the fruit water. Expansion infruit tissue and movement of solutes to the external sugar solution producescontact between sugar and fruit invertase. This invertase action in sucrosewill occur at room temperature, producing an inversion of part of the addedsugar to glucose and fructose. This chemical change in the mixture producesseveral important benefits in jam and jelly quality, including brightness, fruitflavor enhancement, and the avoidance of crystallization in case the concen-tration of sugar is higher than normal.

Sugar addition and maceration of the fruit liberates fruit juice, and thiscan be separated from the pulp for jelly preparation. In jams, macerationsoftens the fruit pieces and helps homogenize the mixture. This solubilizationof sugar permits better distribution in the product during heating and con-centration.

13.2.5 Pectin

Pectin is a very complex molecule formed by a polymer of D-galacturonicacid. The degree of esterification indicates the capacity of the pectin to forma gel. The pectin content and quality are species dependent, meaning thatdifferent fruits have different amounts and quality of pectin.

Gel formation is produced by the relationship between pectin, water inthe fruit, and sugar, under a controlled pH. In high methoxyl pectins, witha degree of esterification greater than 55%, gelation is produced by nonco-valent bonding between polymer chains. In high methoxyl pectins, with adegree of esterification of 70%, hydrogen bonding doubles the hydrophobiccontribution, but is not sufficient to produce gelation, and the participationof sugar is essential to help the hydrophobic interaction between methylester groups in pectin. High methoxyl pectins gel at acid pH (less than 3.5)in the presence of sugar. Low methoxyl pectins, on the other hand, gel athigher pH in the presence of some divalent counterions, of which the mostrelevant is Ca

2+

. Gels are produced when the polymer chains interact to forma continuous three-dimensional polymer network within which the solvent



water is held; this means that high methoxyl pectins will form a gel structurein acid conditions only when the sugar content is greater than 55% and lowmethoxyl pectins (degree of esterification 50% or less) will form gel withlower amounts of sugar (50% or less) and could be used to formulate lowsugar jams and jellies.

4,5

Another division that is used to classify pectins is the time of setting,which is very important to control process conditions. Table 13.2 shows thedifferent setting times for different pectins under standard conditions. Set-ting time is related to the degree of esterification of pectin. Depending onthe nature of the product, the use of different setting times may be necessary.It has been determined that under similar conditions, jams and jellies thatuse high methoxyl pectin can have a reduced taste compared to those madewith low methoxyl pectin. This phenomenon has to do with the effect ofesterification on the taste.

5

13.2.6 Acid

The third essential component in jams and jellies is acid. Normally fruit usedfor making jams and jellies has a low pH; most are less than pH 4.0 andsome are less than pH 3.5. Acid stabilizes the relation between pectin andsugar. High acidity, represented by a pH of 3.2 to 3.4, permits an increasednumber of unionized carboxyl groups in pectin molecules, reducing theelectrostatic repulsion between pectin chains.

5

Berries have low pH due to their content of some common organic acids,such as ascorbic, citric, tartaric, and malic acid. All these acids can be usedto increase the acidity in jams and jellies. A synthetic acid, adipic acid, mayalso be used for the same purpose.

Acids also help produce the inversion of sugar at the beginning of theprocess. Sucrose is converted into glucose and fructose, which may improvethe quality of products by increasing the brightness, reducing crystallization,and reducing the sugar flavor in products.

13.3 Common procedures for making berry jams and jellies

Jams and jellies are differentiated by the amount of pulp they contain, wherejams have all the pulp of the fruit and jellies are only the fruit juice with a verylow pulp content. Jams can be prepared with the whole fruit or fruit pieces.

Table 13.2

Setting Time and Esterification of Different High Methoxyl Pectin

Pectin typeSetting time

(sec)Degree of

esterification Optimum pH

Rapid set 20–70 72–75 3.4Medium set 100–150 68–71 3.2Slow set 180–250 62–66 3.1

Source

: Adapted from Baker et al.

5



Normally products with whole fruit or with large pieces of fruit in heavy sugarsyrup are called preserves; jams have small fruit pieces or pulped fruit.

The main goal in a jam is to form a gel that can be spread or can flowwith consistency. Jelly, on the other hand, consists of a translucent continuousgel with a firmer texture. Both products are made using the same principles:the mixing of fruit, sugar, acid, and pectic substances. Sugar and pectin formthe network that gives each product texture according to the proportions ofthe three ingredients.

2

13.3.1 Fruit and sugar preparation

When manufacturing jams and jellies, the first thing to consider is the qualityof the fruit. Berries are very suitable for these products, but the nature ofthe different species is not the same. There are some fruits that containenough pectin and acid to respond to the addition of sugar. Black raspberriesand blackberries are examples of these fruits. In others, such as blueberriesor red and black currants, the pectin content and acidity depend on theripeness of the fruit.

Since pectin and acid levels determine product quality, when the amountof either of these is not sufficient, addition of a mixture of fruit rich in pectinis one solution; for instance, ripened fruit with unripened fruit, or a blendof different fruits. If a single fruit is used, commercial pectin can be addedif the pectin content of the fruit is low; or if the acid is low, citric acid canbe added.

The fruit used to prepare jams and jellies should be sound, clean, anduniform in ripeness, color, and other characteristics. If fruit pulp or juicepreviously prepared is used, the raw material should be of good quality. Inall cases, fruit materials must be free of pesticide residues.

The sugar used in jam and jelly manufacture, normally sucrose, is refinedcane or beet sugar, but also could be glucose or high fructose corn syrup.The amount of sugar added to the product depends on the final sugar levelin the jam or jelly and the sugar content in the fruit or juice. The flavor ofthese products depends greatly on the flavor of fruit, but added sugar hasan effect on that flavor. Modification of sugar because of heating and reac-tions with fruit components can produce a very strong sugar flavor thatmasks the fruit flavor in jams and jellies. Producing the inversion of sugarand avoiding excessive heating will produce a pleasing fruit flavor.

When the fruit or fruit juice is ready, the sugar is ready, and the pectinand acid level are established, the process can then begin to obtain thetargeted product. Products can be very different, from a normal jam withfruit pieces or whole fruit with 65

°

Brix with some inverted sugar, to a lowsugar jam prepared with frozen pulp with 55

°

Brix pasteurized after beingbottled and sealed, to concentrated pulp and sugar with 65

°

Brix and com-mercial pectin and preservative added. Similar procedures are applied forjellies, from clear juices, inverted sugar, pectin and acid added, to unclearjuice, low methoxyl pectin, and low sugar with 55

°

Brix or less.



To calculate the formulation to obtain a jam or jelly, a simple formuladescribed in Equation 13.1 can be used. This formula calculates the mass ofproduct obtained for a specific mixture of fruit or fruit juice and sugar.Normally an equal proportion of fruit and sugar is mixed at the beginningof the process; if less sugar is used, more water should be evaporated anda reduced yield will be obtained. The fraction of sugar in raw fruit or juiceis usually in the range of 0.08 to 0.15, being a fraction of sugar, 1.0.

Product mass

=

([Fruit or juice mass

×

Fruit sugar fraction]

+

[Sugar mass])/Product sugar fraction (13.1)

As an example, if a jam or jelly is targeted to have 65% sugar, or 0.65sugar fraction, an equal proportion of fruit or juice and sugar are mixed andthe fruit or juice has 15

°

Brix, or 0.15 sugar fraction, the amount of productthat will be obtained is about 88.46 kg/100 kg of raw mixture. If 60 kg offruit is mixed with 40 kg of sugar, under the same conditions and final solublesolids content (65

°

Brix), the yield will be only 75.38 kg.The formula can also be used to obtain the amount of sugar to be added

for a known amount of fruit and given yield of product. However, normallythe amount of sugar will not be much different from the mass of fruit orjuice, except if a lower final sugar content is desired, but this has to beconsidered very carefully because of the standards that define the products,and if the product has less than 65% sugar it should be sterilized.

13.3.2 Jam and jelly manufacture

Jams and jellies are manufactured using the same principles: gel formationby sugar, pectic substances, and acid. These three factors have to be con-trolled in order to permit the formation of gel.

13.3.2.1 Jams

The quality of jams depends on several variables; all of them can be con-trolled with good manufacturing practices, good quality berry fruits, verywell controlled process conditions, and good quality of all other ingredientsused.

3

Fruit can be whole or it can be cut in order to produce homogenizationof the materials during blending and processing.

In general, the less ripe the fruit, the greater the amount of pectin, butthis affects fruit flavor development, which is a critical aspect of productquality. The riper the fruit, the more taste and flavor it has. A mixture offruit of different ripeness may be appropriate to obtain the correct amountof pectic substances as well as flavor and taste. Berries have very specialcharacteristics, and fruits should be selected that have those characteristicsof color, taste, flavor, and acidity.

6

The fruit must be washed carefully to remove all extraneous materials,including stems, hulls, and dust, before making jams; however, some speciessuch as raspberries are very sensitive to manipulation. The fruit has to be



cultivated and harvested in appropriate environmental conditions. Pesticideshave to be eliminated completely before the fruit is harvested. Since theflavor, taste, and color are relevant quality factors for berries, cultivars orvarieties used for processing should have especially high values for theseattributes.

6

Acidity, sweetness, aroma, and strong color are all very importantsensory and nutritional qualities.

Clean and sound fruit is then blended with one-half of the total sugarto be added in order to produce maceration of the fruit and liberation offruit juices to the sugar solution, as well as some of the inversion necessaryto produce a better quality product. The time required for this macerationdepends on fruit ripeness and fruit integrity. Environmental temperature hasto be considered to avoid fermentation of the mixture. To produce the actionof invertase on the added sugar, this operation should be at room tempera-ture. In this first stage, the quality of the fruit is relevant, as the flavor of thefruit passes to the sugar.

After maceration, the mixture is heated to evaporate part of the water. Whenthe temperature increases, if the acid level in the fruit is high enough, an addi-tional inversion of sugar is produced by chemical acid hydrolization of sucrose.This is the only inversion process that occurs in fruit with low levels of invertase.

In fruit with a high acid and high pectin content, this is the moment toadd the rest of the sugar to reach the total sugar level of 65

°

Brix. If the fruitdoes not have enough pectin, commercial pectin has to used, where a mixtureof the required pectin with a similar portion of sugar should be added afterthe concentration process to avoid heat damage to the pectin molecules. Ifthe fruit does not have enough acid, a controlled amount of organic acid,such as citric or malic acid, is added to reach the required pH to producegel formation.

At this point the fruit and sugar are blended, acid has been controlled,and pectin is added in the amount necessary to complement what is con-tained in the fruit. Usually jams have 65% sugar, 1% total high methoxylpectin, and a pH of about 3.2 to 3.4. The latter is an important factor inobtaining the desired texture in the product.

After all factors are controlled, the mixture is heated to a temperature4

°

C to 5

°

C higher than the normal boiling point, which is 100

°

C at sea leveland decreases with height. Therefore the temperature can be a good indexfor finishing jam processing. The product should not be overheated to avoidquality deterioration, such as color changes, pectin content variation,changes in gel formation, and off-flavor development.

When reaching the finished point at 65

°

Brix and the appropriate consis-tency (measured in cold), jams are packaged in glass containers. If the tem-perature is greater than 95

°

C, clean containers can be filled with no previoussterilization; while sterilizing glass containers in water before filling is nec-essary when the temperature is less than 95

°

C, high temperature fillingpermits sterilization of containers and lids.

7

When jams are produced without the use of food preservatives, moldsthat are osmoresistant and temperature resistant may grow; thus products



have to be refrigerated after the containers are open. When storage at roomtemperature is desired, the product should be protected with preservativessuch as sodium benzoate or potassium sorbate at levels of 0.1% of each ifthey are used separately or at 0.1% for a mixture of both. The same practicesshould be considered if the containers are gas permeable.

Figure 13.1 shows a flow diagram of general jam processing. Somedeviations must be considered for low sugar jams, pulped, and sugar-addedfrozen fruits.

13.3.2.2 Jellies

Jellies are very similar to jams and the processing conditions are verysimilar to those for jams. The difference is the starting material, where jamsuse fruit—whole, in pieces, or pulped—jellies are made of strained fruitjuice, preferably clear, and thus require a completely different process atthe beginning.

Another major difference is that in jellies, the natural pectin content infruit juice is significantly lower than in whole or cut fruits or pulps. Theclarification process eliminates most of the cell wall material from the juice,including pectin. Thus almost all the pectin necessary for gelation in jellieshas to be added in the form of commercial grade pectin. The firmness, color,and flavor of the jelly depends on the quality of the juice, the sugar used,and the pectin. As in jam, acid is a very important factor in controllinggelation.

2

Jellies are made of strained juice, sometimes diluted juice concentrates.Normally juice is prepared by cooking fresh or frozen fruit with water.The amount of water will depend on the product. Berries do not needmuch water because of their texture. Juice is easily obtained, especially ifcooking fruit in the presence of sugar or after maceration in a sugarsolution. After cooking, the fruit is pressed to obtain the juice. Pressureshould be enough to produce juice, but avoid destruction of the seed inthe fruit, which can cause severe changes in flavor and deleterious reac-tions in the product.

2

The juice is filtered through a series of strainers and the solids removed.The juice is then stored in appropriate sanitary tanks to permit decantation.Sometimes the juice is clarified in the tanks with the treatment of pecticenzymes to produce clear juice. As mentioned above, this juice is very lowin pectin content, thus additional pectin is necessary for gelation. The pHhas to be maintained at around 3.2 to 3.5 to obtain a good texture. For astandard content of pectin and acid, a low sugar content will produce atough jelly; this can occur if the acid content is low, and syneresis canoccur.

1,5

After sugar is added to the fruit juice, the pectin and pH arecontrolled, the mixture is heated to a boil, and the total sugar level isincreased to 65

°

Brix, controlling carefully the setting of gelation in orderto obtain a good texture.

Depending on the fruit used, different types of pectin are used in jellypreparation. The use of rapid-set pectin permits the development of gelation



Figure 13.1

Flow diagram for commercial jam processing.

Storedfruit


line

Fruit and sugar blendingfruit 50%

sugar 50%

Maceration

Pectin and pHcontrol

Fruit washingand conditioning

Pectin and/or acid additionpectin to 1%

pH to 3.5

Heatingat boiling point

100–105°C

Concentration controlboiling point: 104–105°C at 1 atm

65° Brix

Container fillingnot less than 85°C

Cooling,storing, and

shipping



in a shorter period of time, avoiding long heat treatments. This shorterprocess can help preserve the color and avoid off-flavor development. How-ever, most jelly processors use slow-set pectin for jelly processing, whilerapid-set is preferred for jams.

In some cases, sucrose is replaced by other sugars, such as high fructosecorn syrup, maltose, or glucose syrup. These different types of sugars do nothave the same behaviors as sucrose. These differences need to be considered.One of the changes could be the setting time.

5

Because of the high sugar content, flavor control during the jelly-makingprocess is important. Inversion of sucrose, lowering the total sugar added,controlling acidity, and the use of low temperature and low pressure pro-cesses could be suitable solutions.

If low methoxyl pectin is used to produce jellies, less sugar can be usedand the setting time and temperature can be decreased, producing a betterquality product. A flow sheet for jelly preparation is shown in Figure 13.2.

In jelly processing, preservation is similar to that in jams, where thefilling and closing temperature are very important, and the same care aboutopened jars has to be considered. Good quality jellies do not use preserva-tives, thus open jars have to be kept refrigerated.

13.4 Innovation in berry jam and jelly processing

Innovations in jam and jelly manufacturing in the last decade have beenoriented toward products with a low sugar content, but with similar qualityto traditional products, since the risks of a high glucose index and obesityhave been important issues in last decade. Another important innovation isthe use of low temperatures in the process to retain product quality andnutritional value. The effects of high temperature and long processing timehave been recognized as relevant factors in nutritional and sensory qualitylosses.

13.4.1 Low-sugar jam and jelly manufacture

Jams and jellies are high-energy products, meaning that the products are notsuitable or desirable for people who have glycemic problems, obesity, dia-betes, and cardiovascular risks. Low sugar, on other hand, means difficultiesin gel formation and problems with product texture, stability, and uniformity.Water retention is an important factor in product texture and sugar is impor-tant in stabilizing the network that retains water.

Making low-sugar jams and jellies requires special types of pectin. Somehydrocolloids can be used in low-sugar jam or jelly formulations, but theymay result in different product quality. Another major problem in low-sugarformulations is the flavor that results from artificial sweeteners. The flavorsproduced by sugar are particular characteristics that artificial sweeteners donot have.



To formulate low-sugar jams or jellies, low methoxyl pectin has to beused because of its low-sugar requirements for gel formation. Low methoxylpectin has a different mechanism of action from that of high methoxyl pectin.First, low methoxyl pectin does not need a high sugar content or low pH to

Figure 13.2

Commercial jelly making flow diagram.

Stored freshfruit


line

Washingand

conditioning

Blending fruit andsugar

50 kg fruit20 kg sugar

Heatingto 90°C

Macerationfor 3 h toovernight

room temp

Clothstraining

Pressingsolids

FilteringjuiceDecantation

Adding rest ofsugar, pectin,

and acid30 kg sugar

Evaporation to65° Brix

at boiling temp:100–105°C

Settingcontrol(in cold)

Finalconcentration

65° Brixboiling temp

at 105°C

Hot fillingnot less than

85°C

Cooling andstoring



develop gelation; instead, they require the presence of divalent cations likecalcium. Today there are several calcium compounds that are used with thesepectins that develop gelation in low- or no-sugar media with a high pH.Pectin with a degree of esterification near 50% will need some sugar for gelformation in acidic conditions, while pectins with lower degree of esterifi-cation values can form gel with very low or no sugar content in the presenceof divalent ions and at higher pH values.

5

Pectin that requires some amount of sugar for gel formation in acidicconditions can be used to produce dietetic jams and jellies, with smallamounts of sugar added; those pectins that do not require sugar, but dorequire calcium ions, can be used to make products that contain those ionsand have a higher pH, such as milk products, puddings, and other desserts.

Several artificial sweeteners have been approved for use in the last 25 years.Some of them are very old, such as cyclamates, which were approved foruse in the 1950s and banned in 1970 from use in foods in the United States,the United Kingdom, and other countries. Cyclamates have been reapprovedin several countries, including Canada and some European countries. Severalsweeteners related to the production of low sugar jams and jellies arepresented in Table 13.3.

Most of the sweeteners in Table 13.3 are suitable for used in dietetic jamsand jellies. All of them have broad acceptation and have been proven safe.Two facts are interesting to mention: (1) the special properties of sorbitol and(2) some restrictive properties of aspartame. Sorbitol is a natural compoundpresent in some fruits. It has a low sweetness, only 60% that of sucrose, butit has many other functional properties that are very important in formulatedfoods, including high viscosity for improved body and texture, good humec-tant properties, sequestering properties, and it is a good bulking agent.

8

Aspartame, on other hand, is a very popular sweetener with a very broaduse spectrum. However, aspartame has two very important limitations

Table 13.3

Commercial Sweeteners With the Approval Year, Sucrose Equivalence,

and Usage

SweetenerYear

approvedSucrose

equivalence Usage

Acesulfame K 1988 FDA 200 times sweeter Sweetener: low-sugar jamsAspartame 1981 FDA 200 times sweeter

than 4% sucrose solution

Sweetener in nonsugar jams and jellies

Presents some break–down at high temperatures

Sucralose 1991 Canada, 1998 FDA

600 times sweeter Sweetener: jams and jellies; does not break–down, better flavor

Sorbitol 1974 GRAS 60% as sweet Improves viscosity, humectant, hygroscopicity, sweetener

Source

: From Somogy.

8



according to Somogy:

8

instability on acidic media (conditions that are coin-cident to jam and jelly production), and loss of sweetness when it is heatedfor a long time (another condition that applies to jam and jelly production).Hence aspartame is suitable for use in controlled pH, low- or no-sugardietetic jams and jellies processed under low temperature with vacuumconditions.

Finally, one fact that has to be considered in low- or no-sugar jams andjellies is that these products do not have the water activity depletion agentsugar. Substitutes, such as sorbitol, could have some effect on decreasingfree water and water activity, but the effect is less than that of sucrose. Ifwater activity is not decreased in jams or jellies, they will not be an inter-mediate moisture food, and thus bacteria, molds, and yeast must be con-trolled. Jams and jellies are normally sterilized once they are filled in acontainer and sealed; the same processing as in canned fruits. Since the pHis acid, control of microorganisms in these products is done using pasteur-ization: heating in boiling water (at 100

°

C) for 15 to 20 minutes after jars arehot filled and closed. The jars have to be cooled immediately after heattreatment to avoiding thermoduric microorganism growth.

9

13.4.2 Low pressure and low temperature process

The second innovation in jam and jelly processing in the last decade hasbeen the use of reduced pressure to concentrate the blend of sugar, fruit,pectin, and acid. This technology has replaced the batch atmospheric kettle,with the exception of small-scale production. The system includes a vacuumsystem, devices to produce a continuous concentration process, a pasteur-ization system, and an aseptic filling system. Although a detailed descriptionof this technology for the production of jams and jellies is beyond the scopeof this chapter, the basic principles involved in this system will be discussed.

First, the purpose of applying low pressure and low temperature to thejam and jelly process is to enhance the quality of products to satisfy consumerexpectations. Quality means less heat damage to compounds with biologicalvalue, vitamins, and pigments. Quality also means color, flavor, taste, texture,and homogeneity.

Heating fruits not only causes a loss of flavor and aroma compounds,but may also generate compounds that give the product particular, notalways desired, flavor characteristics. Some studies have reported de novoproduction of sulfur compounds in strawberry puree when heated at 120

°

Cfor 30 minutes. Several compounds were detected and all of them haverelevant significance in strawberry puree sensory characteristics.

10

Most jamand jelly processing was at high temperature for long period of time, thussevere changes in texture, color, and flavor could occur.

When concentration occurs at lower temperatures, most of the highmolecular weight volatiles are not removed from the fruit materials, but stayin the fruit and sugar blend. In order to control volatile losses, the processmust be strictly controlled. Vacuum pressure, temperature, vapor condensation,



and volatiles recovery are some of the factors affecting the efficiency of theprocess.

There are two major modern systems: the continuous process and theautomatic control process. An important consideration is the type of fruitmaterial to be processed. The systems differ if fruit is pulped and a nonpar-ticulate material is flowing in the system or if the material is whole or cutfruit in a mixture with sugar.

13.5 Critical quality and safety factors

Not many changes have been introduced in jam and jelly manufacturing ina long time. The most significant changes in the process have to do withvacuum production, the use of improved pectins, and the introduction ofsynthetic or artificial sweeteners. All these changes have modified onlyslightly the quality of these traditional products. The products found in themarket today are practically the same as those produced 20 or 30 yearsago.

2,3,5,7,11

13.5.1 Quality factors

The main factors affecting the quality of jams and jellies may be divided inquantitative and qualitative. Quantitative factors have to do with the amountof fruit and sugar mixed to give the desired product. Standards

1

require acertain amount of fruit for the product to be defined as a jam or jelly, andthis is very important in terms of customer satisfaction. Other aspects thatinfluence quantitative control are the presence of additives and preservativesthat can significantly affect the quality of the product. It is very importantto consider that the quality of a jam or jelly strongly depends on sensoryperceptions of the product, that is, taste, aroma, texture, and color.

Qualitative factors, on the other hand, depend on the processing as wellas fruit quality. The variety of fruit, maturity, and postharvest treatments arevery important to fruit attributes. Final product quality is strongly dependenton raw fruit quality—the better the fruit quality, the better the final productquality, especially if a heat treatment has to be used in the process.

11

Color is a very important quality indicator, especially in berries, wherered or purple color has been demonstrated to be very attractive for consum-ers. Color is affected by several reactions occurring during processing,including Maillard reactions, ascorbic acid degradation, enzymatic brown-ing, and polymerization of anthocyanins.

6

Another major quality factor is consistency and homogeneity, which aredependent on gel formation, pH, the amount of pectin, and the relationshipbetween sugar and pectin. If the pH is too low, it can cause a very hard gel witha separation of syrup called syneresis. A higher pH can result in a very soft gelwith a runny consistency. Since jams and jellies are very traditional products,small deviations in quality can be very important in determining high, medium,or low acceptance by consumers. Products with no preservatives, packed in



glass, produced with very high quality fruits, ideally red or purple colored, withlow sugar taste and high natural fruit taste, and without heat damage arepreferred. Products that do not use preservatives must be refrigerated after thecontainer is open to avoid fungi development.

Finally, the quality and degree of esterification of the pectin used in jamsand jellies are very important to final product quality. At normal concentra-tions, high methoxylated pectin significantly affects the flavor, while lowmethoxylated pectin has less of an effect. At the same concentration andmolecular weight, a lower degree of pectin esterification significantlydecreases product consistency and changes in flavor. If pectin is altered byreducing its molecular weight, changes in consistency will occur.

12

13.5.2 Nutritional and safety factors

Processing to produce jams and jellies, especially when high temperaturesare used in atmospheric production, may damage some of the valuablecomponents of berries and other fruits. Garcia-Viguera et al.

6

reported thatdifferent cultivars of strawberries present different behaviors for anthocya-nin degradation. All the cultivars present some degradation of anthocyanindue to polymerization and other chemical reactions. Polyphenol oxidase canalso increase the effect of color losses as detected by sensory analysis.

Not only are changes in sensory factors attributed to the degradation ofanthocyanin and other phenol compounds, but also changes in antioxidantcapacity. Kim and Padilla-Zakour

13

showed that in raspberries, even whenthe total phenols and anthocyanin losses are important, the antioxidantcapacity is retained at more than 60% in jam after processing at high tem-perature. Better processes at lower temperatures could improve this behav-ior. Schmidt et al.

14

showed that even when the effect of jam processing inwild and cultivated blueberries did not produce significant losses in totalphenolic compounds and antioxidant activity, it affected other bioactivityforms, such as the antiproliferation power of these species.

Jams and jellies, in general, are very safe when they are prepared undernormal conditions. The large amount of sugar in regular jams and jelliesensures their safety and preservation for long periods of time. In low sugaror nonsugar products, safety depends on processing of the product. Theyhave to be thermally processed because sugar substitutes do not controlwater activity or act as bulking agents. These products require pasteurizationby heating at boiling temperature at normal pressure for about 15 minutes.Normally glass jars have to be cooled after heating in order to avoiding thedevelopment of thermoduric microorganisms. After opening, these productsshould be kept refrigerated.

13.5.3 Packaging

Different types of containers have been used to pack jams and jellies, how-ever, glass is the traditional container for these products. When plastic con-tainers are used, the presence of air and its spoiling effects have to be



considered along with the use of a fungistatic preservative. Plastic containersare usually used for lower quality or bulk institutional products, includingthose used in confectionery and dairy products, such as yogurts.

11

13.6 Applications of berry jams and jellies

13.6.1 Spreads

The main use for jams and jellies is as a spread on bread or crackers aloneor with some other product. The thickness of jams and jellies make themvery useful in cake manufacture, especially when some wet, acid, and sweetingredient is necessary to compensate for the dryness of the dough.

13.6.2 Pastries and cookies

Another major use of jams and jellies is as a filling for pastries, cookies, andbars. Most of these products are ready to eat, but there are some that requirebaking before eating. Berry jams and jellies are very suitable fillings for thesekinds of products because of their acidity and unique flavors. Raspberry,strawberry, blueberry, and others give very distinctive flavors to pastriesmanufactured with their jams or jellies.

13.7 Conclusion

Jams and jellies are not basic foods, but they are good complements to a dietif they are eaten in correct amounts. Jams contains soluble dietary fiber, aswell as vitamin C and minerals, and are high energy foods. They also containseveral high value biological compounds, such as anthocyanin and otherphenolic compounds. Most of these compounds are preserved during jamand jelly manufacture.

Jams and jellies have been produced for centuries and the basics of theirpreparation have not changed. New developments in the use of vacuumevaporation and new types of pectin and sugar substitutes have helped pro-duce better quality and more healthy products that are very appreciated today.

References

1. U.S. Code of Federal Regulations, 21 CFR 150.110, 21 CFR 150.140, 21 CFR150.141, 21 CFR 150.160, and 21 CFR 150.161, revised April 1, 2003, U.S.Government Printing Office, Washington, DC, 2003, p. 450.

2. Woodroof, J.G., Other methods of fruit processing, in

Commercial Fruit Pro-cessing

, Woodroof, J.G. and Luh, D.S., Eds., Avi Publishing, Westport, CT,1975, chap. 10.

3. Splittstoesser, D.F., Microbiology of fruit products, in

Processing Fruits: Scienceand Technology

, Vol. 1,

Biology, Principles and Applications

, Somogyi, L.P.,Ramaswamy, H.S., and Hui, Y.H., Eds., Technomic Publishing, Lancaster, PA,1996, chap. 10.



4. MacDougall, A.J. and Ring, S.G., Pectic polysaccharides, in

Chemical and Func-tional Properties of Food Saccharides

, Tomasik, P., Ed., CRC Press, Boca Raton,FL, 2004, chap. 12.

5. Baker, R.A., Berry, N., and Hui, H., Fruits preserves and jams, in

ProcessingFruits: Science and Technology

, Vol. 1,


,Somogyi, L.P., Ramaswamy, H.S., and Hui, Y.H., Eds., Technomic Publishing,Lancaster, PA, 1996, chap. 5.

6. Garcia-Viguera, C., Zafrilla, P., Romero, F., Abellán, P., Artés, F., andTomás-Barberán, F.A., Color stability of strawberry jam as affected by cultivarand storage temperature,

J. Food Sci.

, 64, 2, 1999.7. Enachescu, M., Fruits and vegetable processing, Agricultural Services Bulletin

119, United Nations Food and Agriculture Organization, Rome, 1995.8. Somogy, L.P., Direct additives in fruit processing, in

Processing Fruits: Scienceand Technology

, Vol. 1,


, Somogyi, L.P., Ra-maswamy, H.S., and Hui, Y.H., Eds., Technomic Publishing, Lancaster, PA,1996, chap. 11.

9. Morris, W.C., Low or no sugar in jams, jellies, and preserves, SP325-F, Agri-cultural Extension Service, University of Tennessee, Knoxville, TN, 2004.

10. Schulbach, K.F., Rouseff, R.L., and Sims, C.A., Changes in volatile sulfurcompounds in strawberry puree during heating,

J. Food Sci.

, 69, 268, 2004.11. Paltrinieri, G.Y. and Figuerola, F.E.,

Procesamiento de frutas y hortalizas mediantemétodos artesanales y de pequeña escala

, 2nd ed., Oficina Regional de la FAOpara América Latina y el Caribe, Santiago, Chile, 1998, p. 255.

12. Guichard, E., Issanchou, S., Descourvieres, A., and Etievant, P., Pectin con-centration, molecular weight and degree of esterification: influence on volatilecomposition and sensory characteristics of strawberry jam,

J. Food Sci.

, 56,1621, 1991.

13. Kim, D.O. and Padilla-Zakour, O.I., Jam processing effect on phenolics andantioxidant capacity in anthocyanin-rich fruits: cherry, plum and raspberry,

J. Food Sci.

, 69, S395, 2004.14. Schmidt, B.M., Erdman, J.W., Jr., and Lila, M.A., Effects of food processing

on blueberry antiproliferation and antioxidant activity,

J. Food Sci.

, 70, S389,2006.


387

chapter 14

Utilization of berry processing by-products

Yanyun Zhao

Contents

14.1 Introduction ............................................................................................... 38814.2 Properties of berry processing by-products ......................................... 388

14.2.1 Pomace as a major berry processing biowaste ....................... 38814.2.2 Basic chemical composition of berry pomace ......................... 38914.2.3 Functional compounds in berry pomace ................................. 391

14.3 Potential food applications of berry pomace ....................................... 39214.3.1 Extraction of anthocyanin pigments ......................................... 39214.3.2 Extraction of phenolic compounds ...........................................39314.3.3 Source of fibers ............................................................................. 39514.3.4 Seeds and their applications ...................................................... 398

14.4 Berry pomace as a substrate for SSF ..................................................... 40114.4.1 Enzyme production of berry pomace through SSF................ 40114.4.2 Biofuel production of berry pomace through SSF.................. 402

14.5 Other potential applications of berry pomace..................................... 40314.5.1 Biodegradable packaging materials .......................................... 40314.5.2 Composting berry processing waste as fertilizer ................... 40414.4.3 Animal feed................................................................................... 405




14.1 Introduction

Along with increased production and processing of berry crops, considerablyhigher ratios of by-products arise. By-products of berry processing representa major disposal problem for the industry, which is further aggravated bylegal restrictions. Meanwhile, berry processing by-products are promisingsources of some compounds that may be used for production and recoveryof value-added ingredients and other products, providing benefit to theindustry. Extraction of anthocyanins, catechins, avonol glycosides, and phe-nolic acids from grape and other berry pomaces has been studied by manyresearchers.

1

A wide range of food and nonfood products, such as tartrates,citric acid, grape seed oil, hydrocolloids, dietary fiber, and ethanol, can berecovered from grape pomace.

2

There are on-going investigations to developother value-added products from berry processing by-products, and effi-cient, inexpensive, and environmentally sound utilization of these materialsis becoming more important.

Because of the large amount of production and processing of grapesamong all berry crops, research and development on the utilization of berryby-products has emphasized on grape processing by-products, typicallygrape pomace. Based on this fact, the discussion in this chapter will concen-trate on the utilization of grape pomace; pomaces from other berry crops,including cranberries, strawberries, and raspberries, will also be covered.

14.2 Properties of berry processing by-products

14.2.1 Pomace as a major berry processing biowaste

Pomace is a primary by-product produced from the traditional fruit juiceand wine-making processes. In 2004 about 5.2 million tons of noncitrus fruitswere processed for juice and wine production in the United States, whichcomprised about 30% of the total utilized production including fresh andprocessed fruits.

3

Apart from oranges, grapes (

Vitis

sp., Vitaceae) are theworld’s largest fruit crop, with more than 60 million tons produced annually.About 80% of the total crop is used in wine making,

4

where approximately20% of the grapes processed turned into pomace, a wine processing biowaste,containing pressed skins, seeds, and stems. Based on this calculation, wineprocessing alone generates more than 9 million tons of pomace annually (5 to7 million tons were reported by Meyer et al.

5

). The composition of the pomacevaries considerably, depending on the grape variety and the technology usedin wine making. The amount of pomace generated from other berry crops,including cranberries, blueberries, strawberries, and raspberries, is alsosignificant, although there are no good statistics in the current literature.Along with increased consumer awareness of the potential health benefitsof grapes, wine, and other berry crops, the production and processing ofberry crops have significantly increased in the past decade and are expectedto increase in the future.


Chapter 14: Utilization of berry processing by-products 389

Berry pomace contains solid materials, including seeds, skins, and some-times stems, and is traditionally utilized as animal feed or fertilizer. How-ever, when used as animal feed, the digestibility is low due to the presenceof large amounts of polyuric polyphenols, which are known to inhibit cel-lulytic and proteolytic enzymes and the growth of some rumen bacteria.

6

Disposal of pomace into the soil or landfills represents a growing problemsince the plant material is usually prone to microbial spoilage and can createserious environmental problems and may face some legal restrictions.

7–9

Berry pomace is a rich source of phytochemicals (antioxidants and nat-ural pigments), pectin, and fibers, and is also an excellent substrate for solidfermentation processing based on its abundant and various nutrients. Hencedeveloping a better knowledge of its chemical and biochemical propertiesand seeking new value-added applications of berry pomace has becomeimperative with the increased production and processing of berry crops.

14.2.2 Basic chemical composition of berry pomace

Compared with reported data on the chemical composition of apple, orange,and pear pomace, information about the chemical composition, especiallythe carbohydrate fraction, of berry pomace is scarce. The following para-graphs summarize the basic chemical composition of a few different typesof berry pomace from the limited literature.

The chemical composition and cell wall materials of cranberries wereanalyzed by Holmes and Chokyun.

10

The chemical composition was ana-lyzed using an extraction from pressed cranberry puree, and cell wall mate-rial was evaluated in both original and centrifugally washed forms. Cell wallmaterial size ranged from 50 µm for individual particles to 400 to 750 µmfor clumps of cells. General particle size was about 20 to 180 µm. The washedcell wall material has the same cellulose content as the unwashed product,while other soluble components of the material had been removed. Thecompositions of the pureed cranberries and washed cell wall material aresummarized in Table 14.1,

showing the only composition data on cranberrypomace that can be found in the literature. This study concluded that thepredominant constitutes of cell wall materials in cranberries are primaryplant cell wall polysaccharides, cellulose, pectin, and hemicellulose, whileprotein, fat, and starch were only present in small amounts. Park and Zhao

11

analyzed the proximate composition of cranberry pomace obtained fromcommercial cranberry juice processing and reported the basic compositionas 85.8% carbohydrates, 8.2% protein, 4% moisture, and 0.8% ash.

The chemical composition of white and red grape pomace from differentgrape varieties has been reported in a few studies. Botella et al.

12

reportedthat white grape pomace (

Palomino fino

variety) has 7.66% moisture content,6.20% ash, 7.13% glucose, 1.5% nitrogen, 9.32% protein, and 0.14% phospho-rus. A comprehensive chemical composition analysis of red and white grapepomace (skins and seeds) was performed by Bravo and Saura-Calixto.

13

Allsamples were rich in protein (12% to 14% dry matter), fat (7% to 12%), and



minerals (6% to 9%), with small amounts of soluble sugars (about 3%) andpolyphenols (4% to 5%) (Table 14.2). Valiente et al.

14

conducted a detailedanalysis on the insoluble (IDF) and soluble dietary fiber (SDF) fractions ofseedless grape pomace (variety Airen) using enzymatic-gravimetric methods

Table 14.1

Composition of Pressed Puree and Washed Cell Wall

Material from Cranberry Juice Processing

Component Pressed puree

Cell wall materialFirst wash Fourth wash

Water 98.5% 97.6% 97.8%Insoluble solids 0.806 2.0 2.197Soluble solids 0.741 0.386 0.053

Total solids

Cellulose 18.1 31.7 37.9Pectin 15.8 14.9 15.4Protein 2.17 2.98 3.37Fat 2.90 2.68 2.57Ash 1.33 0.92 0.87Starch 0.15 0.14 0.14Other sugars 16.3 6.37 0.81Organic acids 8.41 2.96 0.19Glucose 8.18 2.60 0.07Anthocyanins 0.42 0.27 0.04

Soluble solids

Other sugars 34.0 39.4 34.2Organic acids 17.5 18.3 8.15Glucose 17.1 16.1 2.91Pectin 18.3 15.8 26.4Other polysaccharides

4.49 3.29 11.6

Source

: Modified from Holmes and Chokyum.

10

Table 14.2

Chemical Composition of Grape Pomace (Percent Dry Matter)

Red grape skins

White grape skinsWhite grape

seedsComposition Mean STD Mean STD Mean STD

Total dietary fiber 54.16 0.30 59.04 0.88 56.17 0.54Condensed tannins 26.86 1.29 20.47 1.35 15.96 1.70Protein 14.39 0.15 11.60 0.03 12.23 0.43Fat 6.87 0.24 7.78 0.12 12.41 0.11Ash 9.19 0.04 6.89 0.04 5.70 0.01Soluble sugars 2.80 0.56 2.71 0.09 3.02 0.66Soluble polyphenols 3.76 0.05 4.48 0.28 5.22 0.06

STD, standard deviation (

n

=

4).

Source

: Bravo and Saura-Calixto.

13



and reported that dietary fiber constituted 80% of the dry matter, of whichIDF was the major fraction (Table 14.3). The main neutral sugar constituentof IDF was glucose. The major part was cellulose and the remainder, alongwith xylose, was xyloglucan. Uranic acid accounted for 64% of SDF and alarge amount of arabinose, galactose, and mamtose were also included inthat fraction. This study indicated that grape pomace can be a usefulfiber-rich food ingredient.

14.2.3 Functional compounds in berry pomace

Abundant phenolic compounds and antioxidants have been reported inberry fruit pomace, including those from cranberries, raspberries, blueber-ries, and grapes.

15–17

Anthocyanins, catechins, avonol glycosides, phenolicacids, and stilbenes are the principal phenolic constituents of berry pomaces.Recent research has shown that these phenolic phytochemicals possess excel-lent antioxidant properties and thus may have potential beneficial effects onhuman health.

16–18

As a result, a large number of investigations to recoverphenolic compounds from various berry pomaces have been initiated (morewill be discussed in Section 14.3.2). Berry polyphenolics have also been foundto have antimicrobial activity.

19–21

For example, solid-state fermentation (SSF)of cranberry pomace with a food-grade fungus improved the antimicrobialactivity of the pomace and suggested possible mechanisms of action for

Table 14.3

Dietary Fiber Fractions of Seedless Grape Pomace (Airen)

Components Percent dry matter

Dietary fiber

a

IDF SDF

Gravimetric values 68.36

±

0.22 9.53

±

0.06Neutral sugarsRhamnose 0.50

±

0.07 0.28

±

0.00 0.20

±

0.00Fucose 1.24

±

0.13 1.40

±

0.00 0.17

±

0.01Arabinose 2.07

±

0.01 0.83

±

0.05 0.40

±

0.01Xylose 1.70

±

0.17 1.03

±

0.00 0.07

±

0.00Mannose 1.52

±

0.06 1.09

±

0.05 0.24

±

0.01Glucose 14.01

±

0.58 11.34

±

0.60 0.19

±

0.04Galactose 1.60

±

0.06 1.00

±

0.04 0.26

±

0.01Total 22.64

±

0.68 16.97

±

0.98 1.53

±

0.13Uranic acids 5.45

±

0.25 2.80

±

0.16 2.73

±

0.09

Σ

(NS

+

UA)

b

28.09 19.77 4.26Klason lignin 53.64

±

0.20 38.33

±

0.50 —Protein 10.72

±

0.01 58.10 4.26Ash 8.77

±

0.06 6.93

±

0.26 0.50

±

0.01Total 5.77

±

0.33 3.07

±

0.01

IDF, insoluble dietary fiber; SDF, soluble dietary fiber.

a

Mean of three values ± standard deviation.

b

Calculated as the sum of neutral sugars + uronic acids.

Source

: Modified from Valiente et al.

14



phytochemicals.

17

Grape pomace extracts at 1% and 2.5% concentrationsshowed antibacterial effects against 14 bacteria.

20

These antioxidant andantimicrobial activities of berry pomace are valuable and could be the mostimportant functional properties in the development of value-added productsfrom these underutilized fruit processing biowastes. In addition to theirfunctional properties, it has long been known that berry phenolics contributeimportant quality attributes such as color, taste, and flavor in both fresh andprocessed foods.

14.3 Potential food applications of berry pomace

Berry pomace is a by-product of great interest to the food industry since theavailable carbohydrates, phenolic compounds, and pigments can be usedeither as food ingredients or functional constitutes for enhancing the func-tionality of food products. Ethanol, dietary fiber, tartrates, citric acid, foodcolorants, and oils from seeds have been recovered from berry pomace forvarious food applications.

22–23

Extraction of phenolic compounds, includinganthocyanin and polyphenolics, from berry pomace is becoming more com-mon. Although a wide range of products can be converted from berry pom-ace, this chapter will only discuss those that have attracted the most recentinterest in research and development.

14.3.1 Extraction of anthocyanin pigments

Probably the most significant application of berry processing biowaste is theextraction and recovery of pigments and polyphenolic compounds frompomace (both skins and seeds). Anthocyanins are natural pigments in fruitsand vegetables. They are water soluble and exhibit intense red color only ina very limited, strongly acidic pH range between 1 and 3. They can beextracted from grape and other berry pomace,

24–27

and are permitted for useas natural colorants in foods such as soft drinks, jams and jellies, ice creams,pastries, and confectioneries. Anthocyanins also play a significant role inpromoting human health.

Several methods have been developed for anthocyanin extraction, mostoften using acidified alcohols or sulfited water or alcohols.

24–26,28

A simplerecovery system for obtaining anthocyanins from grape pomace wasreported in 1974.

23

Dried pomace was packed in a column and extractedwith methanol containing 1% tartatic acid at a flow rate of 25 ml/min. Themethanol extract was neutralized with 40% potassium hydroxide (KOH)solution to prevent degradation of the anthocyanins. The concentration ofanthocyanins in the concentrate calculated as malvidin-3-glucoside was 0.65g/100 ml. The rate and degree of extraction of anthocyanins from grapepomace depend on a number of factors. Methanol was the best extractant,which was about 20% more effective than ethanol and 73% more effectivethan water.

22

Among the organic acids, citric acid was most effective withmethanol and acetic acid with water.



The kinetics of anthocyanin extraction from fresh and dried grape pom-ace using various solvents was studied by Sriram et al.

29

Six solvents wereemployed, and methanol with 0.1% (v/v) hydrogen chloride (HCl) providedthe highest extraction of 1.18

×

10

3

g/g for dry waste. The same solvent alsoexhibited the fastest kinetics and the shortest time (7 hours) required to attainequilibrium. The kinetics of the extraction were well described by atwo-interface mass transfer model that considered the solvent diffusioneffects on the mass transfer coefficients. Equilibrium and holdup studieswere also carried out using the safest solvent for human consumption fromamong the solvents used for extraction.

Supercritical water extraction of anthocyanins from elderberry and rasp-berry pomace was evaluated using a flow-through extraction system inwhich water and acidified water solutions were fed at a high velocity withthe aid of a booster pump in an attached Spe-ed unit module (AppliedSeparations Inc., Allentown, PA).

30

Samples were placed in the extractioncell and the oven was heated to temperatures between 120

°

C and 160

°

C.Both deionized and Milli-Q-purified neat water as well as acified water(0.01% HCl, pH ~ 2.3) were fed, typically at a rate of 24 ml/min, against aconstant pressure of 40 bar. Similarly, rapid extractions were conducted onan accelerated solvent extraction (ASE) system (Model 300, Dionex Corp.,Sunnyvale, CA) using both pure water, water-ethanol mixtures, and acidifiedwater. Subcritical water extraction was highly efficient at recovering antho-cyanins from berry substrates and complimented both mechanical expres-sion and supercritical carbon dioxide (scCO

2

) extraction for juice and oilrecovery from fruit berries. The derived extracts appeared equivalent orbetter than those obtained via ethanol-based extractions with respect to theircomposition, nutritional value, and antioxidant activity. In addition, the useof water above its normal boiling point facilitated in situ sterilization of theextract, similar to that experienced using thermal retorting.

14.3.2 Extraction of phenolic compounds

Kammerer et al.

1

recently conducted a comprehensive review on the recoveryand characterization of phenolic compounds in grape pomace from differentgrape cultivars. Polyphenol screening of pomace from both red and whitegrape varieties was reported, and the novel polyphenol recovery methodsfrom grape pomace and their effect on recovered phenolic content were alsodiscussed. In most studies, quantitative data were determined for somerepresentative compounds

31–33

or expressed as total phenolic contents, whichwere correlated with the antioxidant activity of pomace extracts.

34–38

Although products containing grape skin or grape seed extracts are com-mercially available,

39

the extractability of nonanthocyanin phenolics and thecontents of individual compounds in these extracts have been investigatedsimply on the basis of total phenolics or some representative compounds.

40

Detailed quantitative data are of particular importance because individualphenolics may differ considerably in their bioavailability and bioactivity.



Kammerer et al.

41

screened phenolic contents in 14 pomace samplesoriginating from red and white wine making by high performance liquidchromatography mass spectrometry (HPLC-MS). Up to 13 anthocyanins, 11hydroxybenzoic and hydroxycinnamic acids, and 13 catechins and flavonols,as well as 2 stilbenes, were identified and quantified in the skins and seedsby HPLC diode array detector (HPLC-DAD). Large variabilities comprisingall individual phenolic compounds were observed, depending on the culti-var and vintage. Grape skins proved to be rich sources of anthocyanins,hydroxycinnamic acids, flavanols, and flavonol glycosides, whereas fla-vanols were mainly present in the seeds. However, besides the lack of antho-cyanins in white grape pomace, no principal differences between red andwhite grape varieties were observed. The results confirmed that both theskins and seeds of most grape cultivars constitute a promising source ofpolyphenolics.

Extraction of phenolic compounds from other berry pomace has alsobeen reported. Zheng and Shetty

8

investigated the potential of using cranberrypomace as a substrate for the production of free phenolics and

b

-glucosidasethrough SSF by a food-grade fungus,

Lentinus edodes

. It was found that

L.edodes

b

-glucosidase played a major role in the release of phenolic aglyconsfrom cranberry pomace during SSF. After 50 days of cultivation, the yield oftotal free phenolics reached the maximum of 0.5 mg/g of pomace, while the

b

-glucosidase activity was about 9 units/g of pomace. The enzyme exhibitedoptimal activity at 60

°

C and at pH 3.5 and was stable at temperatures up to50

°

C and between pH 3 and 6.5. The major free phenolics produced fromcranberry pomace were identified by HPLC as gallic acid, chlorogenic acid,

p

-hydroxybenzoic acid, and

p

-coumaric acid. The results suggest that cran-berry pomace is a potential substrate for producing food-grade phenolicsand fungal

b

-glucosidase. Vattem and Shetty

18

further investigated the changes and mobilizationsof simple phenolics and diphenyls and their antioxidant properties in cran-berry pomace processed by solid-state growth using the same food-gradefungus,

L. edodes

, as well as the role of

b

-glucosidase in the mobilization ofphenolic antioxidants by hydrolysis of the glycosides. Increased extractablephenolic content was found during the SSF process. Antioxidant activity alsoincreased over the course of growth. HPLC analysis indicated that the cran-berry pomace was enriched with ellagic acid to a level of 350 mg/g dryweight (DW) of pomace. It was concluded that the antioxidant capacity ofcranberry pomace can be improved through a solid-state process. The pro-cess resulted in enrichment of the pomace with ellagic acid, an importantphytochemical with anticarcinogenic and cardioprotective properties, andpermitted an alternative of cranberry pomace as a functional ingredient fordiverse food and feed applications.

Lee and Wrolstad

27

evaluated juice processing enzymes and a numberof processing parameters for producing aqueous blueberry extract that wasrich in anthocyanins and polyphenolics. The effectiveness of temperature,sulfur dioxide (SO

2

), citric acid, and industrial juice processing enzymes for



producing extracts of blueberries (

Vaccinium corymbosum

cv. Rubel) and blue-berry skins that are rich in anthocyanins and polyphenolics were evaluatedindividually or in combination. It was found that enzyme treatment hadlittle effect on the total monomeric anthocyanins and on total phenolicsrecovery. Various combinations of heat, SO2, and citric acid yielded extractswith higher concentrations of anthocyanins and total phenolics than thecontrol. Anthocyanins existed almost exclusively in the skins and polyphe-nolics were mostly in the skins, with lesser amounts in the flesh and seeds.The skins were also highest in antioxidant activity. All portions containedthe same individual anthocyanins, but in varying amounts. Cinnamic acidderivatives and flavonol glycosides were found in the skins and seeds,whereas the flesh contained only cinnamic acid.

It is important to note that the methods of sample preparation andextraction have a significant impact on the recovery of polyphenolic com-pounds from berry pomace. Drying of pomace at high temperatures beforeextraction can cause a significant reduction in extractable polyphenols andmay also affect antioxidant activity and free radical scavenging capacity.Enzymatic treatment of pomace usually enhances the release of phenoliccompounds. Gamma irradiation extended the shelf life of grape pomace andimproved anthocyanin yields.42 Extraction of crushed grape pomace with amixture of ethyl acetate and water yielded phenolic compounds displayingantioxidant activities comparable to butylated hydroxytoluene (BHT) in theRancimat test.43 The use of superheated solvents also impacts the extractionof phenolics from grape pomace.44

14.3.3 Source of fibers

Several studies have investigated the potential of using grape pomace as asource of dietary fiber in food applications. Saura-Calixto et al.45 reportedthat IDF and Klason lignin residues in grape pomace contained appreciableamounts of condensed tannins and resistant protein. The presence of con-densed tannins and resistant protein in the residues obtained after the suc-cessive action of amylase, protease, and amyloglucosidase and chemicaltreatments with sulfuric acid (H2SO4) and HCl-triethylene glycol could beconsidered in a wider definition of the dietary fiber complex as “indigesiblepolysaccharides, phenolic polymers and resistant protein,” where the term“phenolic polymers” includes both lignin and condensed tannins.

Insoluble and soluble dietary fiber fractions of grape pomace, obtainedby enzymatic-gravimetric methods, were analyzed for neutral sugars, uranicacids, Klason lignin, and amino acids (Table 14.3).14 Dietary fiber constituted80% of dry matter, of which IDF was the major fraction. The main neutralsugar constituent of IDF was glucose. The major part was cellulose and theremainder, along with xylose, was xyloglucan, which also contained fructose.Uranic acids accounted for 64% of SDF and a large amount of arabinose,galactose, and mannose were also included in that fraction. Proteins werenot well solubilized by the assay enzymes. During the isolation of dietary



fiber fractions, a considerable solubilization of polyphenols was observed.These compounds were associated with Klason lignin in the startingmaterial.

Bravo and Saura-Calixto13 performed a comprehensive chemical charac-terization of the indigestible fraction of the main parts of grape pomace(skins and seeds, separately) (Table 14.2 and Table 14.4). About 17% to 20%of the dry matter was nonstarch polysaccharides (NSP), mainly cellulose andpectin. The condensed tannins content was very high, ranging from 16.0%in white grape seeds to 26.9% in red grape seeds. A very high percentage ofthe protein (up to 80%) was also indigestible in vitro, appearing as resistantprotein in the fiber residue. The study concluded that more than 60% of thegrape pomace dry matter was indigestible in vitro, which was composed ofdietary fiber (NSP plus lignin) as well as condensed tannins and resistantprotein. The presence of large amounts of condensed tannins and resistantprotein provides grape pomace with peculiar physiological and nutritionalproperties.

More recently, understanding of the antioxidant activity of grape pomacehas led to the development of a new concept of “antioxidant dietary fiber”(ADF), defined as a product containing significant amounts of natural anti-oxidants associated with the fiber matrix.46 ADF, rich in both dietary fiberand polyphenolic compounds, was extracted from red grape pomace, asgrape polyphenols remain in grape pomace after wine making, mainly inthe skins and seeds. The study found that both nonextractable proanthocy-anidins (28.6%) and extractable polyphenols (2.0%) are associated with thedietary fiber matrix. When determining the antioxidant capacity in vitro bylipid oxidation inhibition and free radical scavenging procedures, it wasfound that 1 g of product showed similar lipid oxidation inhibition and freeradical scavenging effects as 400 mg and 100 mg of DL-a-tocopherol, respec-tively. Extractable polyphenol of grape ADF showed a higher antioxidantcapacity than red wine polyphenol. It was concluded that grape pomace isa suitable material for obtaining ADF, and ADF could be used as a new foodingredient. In addition to the properties derived from ordinary dietary fibers,a prevention of lipid oxidation in food products can be expected from thepresence of antioxidant polyphenols. The potential combined actions of non-extractable proanthocyanidins and bioavailable flavonoids of the ADF arepromising in nutrition and health.46

These studies suggest that grape pomace could be important in thefood industry as a high dietary fiber ingredient. It is a rich source ofhemicellulose and cellulose, with a lower proportion of pectin, all of whichare important in human nutrition. The potential effects expected from sucha by-product would be mainly related to those associated with insolublefibers, such as regulation of bowel functions and water retention. Adsorp-tion of organic compounds could also be expected, since reported studies47

have shown that certain grape pomace exhibited potent hypocholester-olemic activity in rats.



Tabl

e 14

.4C

ompo

siti

on o

f th

e D

ieta

ry F

iber

Fra

ctio

ns o

f G

rape

Pom

ace

(Per

cent

Dry

Mat

ter)

Red

gra

pe

skin

sW

hit

e gr

ape

skin

sW

hit

e gr

ape

seed

sID

FSD

FID

FSD

FID

FSD

FM

ean

STD

Mea

nST

DM

ean

STD

Mea

nST

DM

ean

STD

Mea

nST

D

Ara

bino

se0.

680.

030.

290.

031.

030.

070.

530.

070.

800.

020.

450.

07X

ylos

e1.

540.

070.

000.

002.

310.

070.

000.

002.

490.

100.

000.

00M

anno

se1.

160.

050.

000.

000.

900.

060.

000.

000.

850.

020.

000.

00G

alac

tose

0.71

0.03

0.00

0.00

1.00

0.05

0.00

0.00

0.77

0.03

0.00

0.00

Glu

cose

8.46

0.16

0.00

0.00

8.74

0.28

0.00

0.00

7.31

0.51

0.00

0.00

Tota

l NS

12.5

40.

300.

290.

0313

.98

0.50

0.53

0.07

12.2

10.

580.

450.

07U

roni

c ac

ids

3.21

0.07

2.32

0.27

4.64

0.33

4.39

0.32

3.75

0.09

3.14

0.04

(NS

+ U

A)

0.9

14.1

70.

312.

340.

2516

.76

0.71

4.43

0.25

14.3

70.

573.

230.

07K

laso

n lig

nin

37.6

40.

34—

—37

.85

0.45

——

38.5

70.

32—

—To

tal d

ieta

ry

fiber

51.8

10.

372.

340.

2554

.61

1.07

4.43

0.25

52.9

40.

473.

230.

07

IDF,

inso

lubl

e d

ieta

ry fi

ber;

NS,

neu

tral

sug

ars;

SD

F, s

olub

le d

ieta

ry fi

ber;

ST

D, s

tand

ard

dev

iati

on (

n =

4);

UA

, uro

nic

acid

.So

urce

: Bra

vo a

nd S

aura

-Cal

ixto

.13



14.3.4 Seeds and their applications

Seeds account for 20% to 26% of berry pomace by weight. The basic chemicalcompositions of grape and other berry seeds have been reported in severalstudies. Table 14.5 shows the basic chemical composition and mineral con-stitutes of grape seeds and the fatty acid profile of grape seed oil.

Grape seeds are rich sources of polyphenolics, especially procyanidins,which have been shown to act as strong antioxidants and exert health-promoting effects. Grape seed extracts contain proanthocyanidins, oligomers,and polymers of polyhydroxy flavan-3-ols.49 Proanthocyanidins hold tremen-dous interest because of their antioxidant activity. Grade seeds are one of therichest sources of proanthocyanidins in nature. Proanthocyanidins containingtwo or more monomers chemically linked together are called oligomericproanthocyanidins (OPCs). It has been reported that the antioxidant powerof OPCs in grape seeds is approximately twice that of vitamin E and fourtimes that of vitamin C. Some of the health benefits of OPCs include49

• Enhancement of the absorption of vitamin E and C by sparing themfrom oxidation in the body.

• Prevention of cardiovascular disease, arthritis, hypercholesterolemia,and some age-related cancers by scavenging the free radicals associ-ated with many chronic degenerative conditions.

• Improvement of blood pressure regulation by increasing blood flow,thus a benefit to those suffering from hypertension.

• Inhibition of human cancer cells (breast, lung, and stomach) com-bined with promotion of normal, healthy cell growth.

• As anti-inflammatory agents to manage swelling of joints, reducearthritis pain, and mend damaged tissue.

• Prevention of the degradation of mast cells, which in turn releasehistamines, thus promising relief for those suffering from allergiesand other sinus problems.

Table 14.5 Chemical Composition and Mineral Constitutes of Grape Seeds, and Fatty Acids of Seed Oil

Chemical composition Mineral constitutes Fatty acids of seed oilPercent dry weight base Mineral ppm Fatty acid Percent

Crude protein 8.2 Copper 9.1 Myristic 0.08Crude oil 14.0 Zinc 11.4 Linolenic 0.24Total ash 2.2 Iron 33.5 Palmitoleic 0.60Crude fiber 38.6 Magnesium 1215 Stearic 3.9Carbohydrate 37.0 Phosphorus 2200 Palmitic 7.4Moisture 43.1 Calcium 4026 Oleic 15.6

Potassium 4276 Linoleic 15.6

Source: Modified from Kamel et al.48



Grape seed extracts have been sold in the market as a dietary supplementin Japan since 1993.51 It has been added to food, beverages, and cosmetics,transforming conventional offerings into functional products. More power-ful than tocopherol and ascorbic acid, grape seed extracts can inhibit oxida-tive reactions such as those responsible for lipid and vitamin oxidation, aswell as the off-flavors and colors that often result. In addition, grape seedextracts display properties of an emulsifier in oil-and-water systems. Forexample, grape seed extracts in conjunction with green tea extract wereadded to chicken breast prior to irradiation to minimize undesirable flavor,odor, and color changes. Grape seed extracts have also been added to frozendesserts, creating functional ice cream.50 Some grape seed extracts have beengranted generally recognized as safe (GRAS) status, initially for use as anti-oxidants in nonstandard identity fruit juices and fruit-flavored beverages atlevels up to 210 ppm, and later for cereals, bars, and yogurt products. Morerecently, levels ranging from 0.01% to 0.08% have been specified for use inbeverages and beverage bases, breakfast cereals, fats and oils, dairy dessertsand mixes, grain products, milk and milk products, processed fruits, andfruit juices.50

Grape seed oil has significant value. As shown in Table 14.5, the averageoil content of grape seeds is about 14%, ranging from 13% to 18% for allvarieties.22 Grape seed oil can be recovered by mechanically pressing or bysolvent extraction of ground seeds. The oil has a low saturated fatty acids(palmitic, stearic) content, but contains a very high level of linoleic acid, anessential fatty acid for humans (Table 14.5). Hence its fatty acid compositionrenders it very desirable for inclusion in diets and foods designed for low-ering serum cholesterol and saturated fatty acids. Grade seed oil also has apleasant flavor and is stable when used as a frying-oil.

The majority of information on caneberry seeds has concentrated onred raspberry (Rubus idaeus L.) seeds. Red raspberry seeds are reported tocontain 12.2% protein and 11% to 23% oil. The seed oil contains 54.5%linoleic acid (18:2), 29.1% R-linolenic acid (18:3), 12% oleic acid (18:1), and4% saturated fatty acids.52 The percentage of R-linolenic acid is similar tohemp, black currant, and cranberry oils and may have utility based onpotential health benefits. Considerable amounts of tocopherols have beenfound in red raspberry oil, mainly a-tocopherol. Tocopherols are commonlipophilic antioxidants abundant in some oils and nuts, but their presencein red raspberry seeds could provide vitamin E activity and antioxidantpotential as well. Ellagic acid was reported to be more abundant in redraspberries and blackberries (Rubus sp.) than in other fruits and nuts. Occur-ring primarily in the seeds, ellagic acid has shown chemopreventive activityin animal models. These characteristics of red raspberry seeds suggestpossible roles in human nutritional products.

A study investigating the chemical composition and antioxidant potentialof the seeds from five commonly grown caneberry species: red raspberry, blackraspberry, bysenberry, Marion blackberry, and Evergreen blackberry, showedthat seeds from all five species had 6% to 7% protein and 11% to 18% oil.53



The oils contained 53% to 63% linoleic acid, 15% to 31% linolenic acid, and3% to 8% saturated fatty acids (Table 14.6). The two smaller seeded raspberryspecies had higher percentages of oil, the lowest amounts of saturated fattyacid, and the highest amounts of linolenic acid. Ellagitannins and free ellagicacid were the main phenolics detected in all five caneberry species and wereapproximately threefold more abundant in blackberries and boysenberriesthan in raspberries. Each of the caneberry species has its own distinguishingcompositional profile, and as a group they can be defined by their abundanceof R-linolenic acid, ellagic acid, and antioxidant capacity.53

Seed oils from caneberries have been incorporated in cosmetics andpharmaceutical products based on their anti-inflammatory activity, notablyfor the prevention of gingivitis, rash, eczema, and other skin lesions.52 Theanti-inflammatory activity of raspberry seed oil was superior compared tothose of other well-known oils such as virgin avocado oil, grape seed oil,hazelnut oil, and wheat germ oil. Raspberry seed oil may also be used insunscreen, toothpaste, and cream for prevention of skin irritations, as wellas incorporated into bath oil, aftershave, antiperspirant, shampoo, andlipstick.

Table 14.6 Caneberry Seed Amino Acid Composition

mg/100 g

Amino acidRed

raspberryBlack

raspberryMarion

blackberry BoysenberryEvergreen blackberry

Glutamic acid 1.40 1.60 1.56 1.33 1.48Aspartic acid 0.68 0.76 0.69 0.64 0.72Arginine 0.54 0.58 0.58 0.54 0.59Leucine 0.47 0.49 0.46 0.44 0.49Glycine 0.40 0.40 0.44 0.40 0.48Alanine 0.33 0.34 0.30 0.36 0.31Valine 0.33 0.34 0.32 0.31 0.35Isoleucine 0.32 0.34 0.32 0.30 0.35Lysine 0.3 0.32 0.29 0.29 0.30Phenylalanine 0.28 0.29 0.27 0.26 0.30Proline 0.27 0.31 0.27 0.26 0.32Serine 0.27 0.27 0.25 0.23 0.25Threonine 0.23 0.24 0.22 0.22 0.23Histidine 0.18 0.19 0.20 0.19 0.20Cysteine 0.17 0.19 0.18 0.14 0.16Tyrosine 0.14 0.15 0.14 0.13 0.15Methionine 0.14 0.14 0.14 0.12 0.13Hydroxyproline 0.04 0.04 0.03 0.04 0.06Tryptophan 0.04 0.04 0.04 0.04 0.04Taurine 0.01 0.06 0.06 0.05 0.05Omithine 0.01 0.01 0.01 0.01 0.01

Source: Bushman et al.53



14.4 Berry pomace as a substrate for SSFSolid-state fermentation is considered an appropriate approach for processessuch as the bioremediation or biodegradation of toxic compounds, detoxifi-cation of agricultural wastes, and biotransformation of crops and biopulping.SSF has been successfully applied in the preparation of new high valueproducts, such as secondary metabolites, organic acids, pesticides, aromaticcompounds, fuels, and enzymes,12 and has been used for biological conver-sion of fruit processing wastes into value-added products. SSF involves thegrowth of microorganisms on wet solid supports in the absence (or nearabsence) of free water. The advantages of SSF in comparison to traditionalsubmerged fermentation are better yields, easier recovery of products, theabsence of foam formation, and smaller reactor volumes. Moreover, contam-ination risks are significantly reduced due to the low water content, andconsequently the volume of effluents decreases.12

The growth of several agriculturally and industrially important fungion cranberry pomace substrate through SSF has been studied by Zheng andShetty.54 Fungi, such as Trichoderma viride If-26, Trichoderma harzianum ATCC24274, and Trichoderma pseudokoningii ATCC 26801, a novel polymeric dyedecolorizing Penicillium isolate, and a food-grade Rhizopus strain isolatedfrom Tempeh, that produce industrially important extracellular enzymeswere grown on a cranberry pomace-based medium at 25°C for 4 days. Themaximum growth of all fungi was established on cranberry pomace supple-mented with 0.05 g of calcium carbonate (CaC3), 2.0 ml of water, and 0.05 gof ammonium nitrate (NH4NO3) or 0.2 ml of fish protein hydrolysate pergram of pomace. It was concluded that bioconversion of cranberry pomaceby industrially beneficial fungi through SSF is feasible. The production offood processing enzymes and ethanol from grape and other berry pomacethrough SSF is briefly discussed below.

14.4.1 Enzyme production of berry pomace through SSF

Recently there has been increased interest in the production of enzymesfor food processing applications from berry fruit pomace using SSF. Themicroorganisms in solid-state cultures grow under conditions close to theirnatural habitats, thus they may be more capable of producing certainenzymes and metabolites, which usually will not be produced or will beproduced only at low yield in submerged cultures. Cranberry and straw-berry pomace were both used as substrate for polygalacturonase produc-tion by Lentinus edodes through SSF.9 Polygalacturonase is widely used inthe food processing industry as a processing aid in maceration, liquefac-tion, extraction, clarification, and filtration of fruit and vegetable juicesand wines. The study found that strawberry pomace was a better substratefor the highest polygalacturonase yield, but not cranberry pomace. Thepolygalacturonase produced by L. edodes from strawberry pomace exhibiteda maximal activity at 50°C and pH 5. The enzyme was fairly stable up to



50°C and between pH 3.0 and 6.5. Considering the natural acidic pH ofmost fruit and vegetable tissues and juices, the acid-tolerant property ofL. edodes polygalacturonase makes the enzyme an ideal candidate for tissuemaceration, juice extraction, and clarification in the fruit and vegetableprocessing industry.

In another study by Moldes et al.,55 grape seeds were used by Trameteshirsuta as a substrate for laccase production. Laccases are copper-containingenzymes that catalyze the oxidation of a wide variety of organic and inor-ganic substrates. The laccase production was 10-fold the value attained inthe cultures with no grape seed addition.

Botella et al.12 recently showed that grape pomace is the sole nutrientsource for SSF to produce hydrolytic enzymes (cellulases, xylanases, andpectinases) using Aspergillus awamori and could be competitive with othertypical agroindustrial wastes used as substrates in SSF processes. Xylanaseand exo–polygalacturonase activities were high compared with correspond-ing values in the literature, showing good future prospects for industrialapplications. Cellulase activity is inhibited. Endo-polygalacturonase showsa catabolic repression when the reducing sugar concentration in the mediumis high (during the first few hours), and its activity increases when thereducing sugars decrease.

In summary, grape and other berry fruit pomaces are good natural mediafor SSF. Their chemical composition is rich in the main nutrients requiredfor the growth of a wide range of microorganisms. The low cost of thesematerials make them potentially promising for such applications.

14.4.2 Biofuel production of berry pomace through SSF

A significant amount of fermented sugar is present in berry pomace and canbe at least partially degraded to release mono- and disaccharides that canbe utilized or fermented by yeasts. The feasibility of ethanol production fromgrape pomace under SSF conditions was first studied by Hang and Woodamsin 1986.56 More than 53 g of ethanol were produced per kilogram of grapepomace fermented, and the yield of ethanol amounted to 81% to 82% of thetheoretical, based on the quantity of fermented sugar consumed. It wasfound that the naturally occurring yeast flora fermented grape pomace asefficiently as the commercially available wine yeast species under SSF con-ditions, and temperature has a profound influence on the ethanol fermenta-tion of grape pomace.

Korkie et al.57 isolated naturally occurring microorganisms from grapepomace and evaluated them for their ability to hydrolyze the complexpolysaccharides found in grape pomace and to utilize the fermented sugarfor the production of ethanol. Two Pichia rhodanensis isolates were able topartially hydrolyze the pomace polysaccharides, but fermentation of thepomace resulted in only a small increase in the amount of ethanol produced.The study revealed that significant amounts of ethanol (about 15 g/l samplesolution) could be obtained from the residual sugars associated with



grape pomace. However, the complex structure of the pomace polysaccharidesapparently renders it unsusceptible to efficient hydrolyzation under fermen-tative conditions. It was suggested that yeast that is able to both hydrolyzethe polysaccharides in grape pomace and ferment the sugars to ethanol shouldbe utilized.

Pramanik and Rao58 investigated the kinetics of ethanol fermentation ofgrape waste by Saccharomyces cerevisiae yeast isolated from toddy. The bestethanol production rates were observed at pH 4.5 and a temperature of 30˚C.At sugar concentration of 150 g/l, a maximum ethanol concentration andethanol productivity of 73.7 g/l and 0.84 g/l were obtained with 0.5 g/gethanol yield and 95% sugar utilization. Both yeast growth and ethanolinhibition were obtained at a higher sugar concentration of 200 g/l.

14.5 Other potential applications of berry pomace14.5.1 Biodegradable packaging materials

Polysaccharides, including cellulose, pectin, and starches, are the commonmaterials for making edible and biodegradable films and other types ofpackaging materials. Berry pomace contains solid materials, including seeds,skins, and fibers, and is a rich source of valuable pectin, fibers, pigments,and other functional compounds. These compounds may be extracted frompomace to make edible films that provide unique characteristics (naturalfruit flavor and color) that other film-making materials do not have, thusattracting more potential applications. Meanwhile, pomace containing seedsand skins can be used directly as a base material for creating biodegradablepackaging materials (boards and containers) for various food and nonfoodapplications (S.-I. Park et al., unpublished data, 2005).59

The feasibility of using cranberry pomace extract as a new film-formingmaterial was studied recently by Park and Zhao.11 About 1.4% (w/w) ofsolids was obtained from cranberry pomace water extracts, of which about93% was carbohydrate. Low methoxyl pectin (LMP) or high methoxylpectin (HMP) at a concentration of 0.50% or 0.75% (w/w) and 0.25% (w/w)sorbitol or glycerol was incorporated into film-forming solutions toimprove film functionality. Dried films had a bright red color and a strongcranberry flavor. In general, LMP and sorbitol films had a higher tensilestrength and lower elongation at break and lower water vapor permeabilitythan other films. The higher (0.75%) pectin concentration resulted inincreased tensile strength, but decreased elongation at break. Scanningelectron microscopy images revealed that sorbitol-added films had moreregular and compact cross-section structure than those of glycerol-addedfilms. This study demonstrated that it is feasible to create natural colorfulfruit-flavored edible films from berry pomace water extracts. Dependingon the specific applications of the films, targeted film functionality can beachieved by incorporating proper amounts of pectin and plasticizer intothe pomace extracts.



Whole berry pomace may be directly used to manufacture biocompositesthat are then further converted into packaging materials (boards or contain-ers). Biocomposites are biodegradable composites composed of biodegrad-able polymers as the matrix material and containing biodegradable fillers.60

After the extraction of functional substances from whole pomace, only asmall fraction of the pomace is utilized, and most of the water insolublepomace components remain as biowaste. Whole fruit pomaces or these pom-ace residues can be further utilized to create biocomposites by incorporatingother biopolymers. Since the market for petroleum-based polymers will belimited in the future because of ecological concerns and resource availability,the development of biodegradable polymers from renewable resources hasbecome very important. Berry pomace is a good candidate for making bio-composites because some pomace components (pectin, protein, organicacids, and sugars) have thermoplastic characteristics. These thermoplasticcomponents can form the composite matrix, and the nonthermoplastic parts,mainly fibers and minerals, may act as dispersed filler. Biodegradable plas-tics from renewable resources (starch, lignocellulose, and protein) may beutilized to augment the matrix for fruit pomaces during thermal processing.Sorbitol and glycerol may be added to the mixture to reduce the brittlenessof the formed composites. Hydrophobic materials, such as waxes and fattyacid esters, may be helpful for improving the water resistance of the com-posites. Such biocomposites should have broad applications as packagingmaterials (S.-I. Park et al., unpublished data, 2005). However, this is a verynew area of potential applications for berry pomace, and significant researchis needed to obtain fundamental knowledge of the binding mechanisms ofpomace with other polymers and the manufacturing technologies for pro-cessing these products.

14.5.2 Composting berry processing waste as fertilizer

The fertilizer value of grape waste has long been known. In the scantyliterature on the subject, the value of pomace has been described primarilyin terms of its nitrogen contribution, with less emphasis on other nutrientsand characteristics. A benefit of raw grape pomace that has often beenoverlooked is the effect of the added organic matter on soil structure,water penetration, and enhancement of nutrient availability. Moreover,composted grape pomace provides nutrients in a more concentrated andstable form than raw pomace. In addition, application of raw pomacecould result in several dozen seedlings in a 10 ft.2 area, while a similarapplication of finished compost of unblended pomace may yield only oneor two seedlings.61–62

Compositing is the aerobic biological decomposition and stabilizationof organic substrates, under conditions that allow development of thermo-philic temperature as a result of biologically produced heat, to obtain a finalproduct that is stable and free of pathogens and plant seeds that can bebeneficially applied to land.62 The application of compost increases the



percentage of organic matter, nutrient levels (providing slow fertilizationover a long period of time), and microbial biomass, and improves the physicalproperties (aeration, water-holding capacity, etc.) of soils.63

Typical moisture and nutrient contents of grape waste were reported byIngels,61 in which the stems contain 65% moisture, 0.9% nitrogen, 1.2% potas-sium, and 0.1% phosphorus; skins contain 70% moisture, 0.3% nitrogen, 0.6%potassium, and 0.1% phosphorus; wet pomace contains 50% moisture, 0.9%nitrogen, 1.0% potassium, and 0.25% phosphorus; and compost contains 30%moisture, 1.5% nitrogen, 2.0% potassium, and 0.5% phosphorus. Bertran et al.62

evaluated the simplest and least expensive compositing program usingwinery sludge and grape stalks in two proportions (1:1 and 1:2 sludge andgrape stalks (v/v)). The best results were obtained in the compost heap inwhich the residues were mixed in the proportion of 1:2 and where the grapestalks had been previously ground. Optimum results required a moisturecontent of about 55%, a maximum temperature around 65°C, and an oxygenconcentration not lower than 5% to 10%. The resulting compost had highagronomic value and was particularly suitable for the soils of vineyards,which have a very low organic matter content. The compost can be reintro-duced into the production system, thereby closing the residual material cycle.

14.4.3 Animal feed

Grape and other berry pomaces are polyphenol and dietary fiber rich mate-rials. Their use as animal feed has been tested for pigs, rats, sheep, andcows.64–67 However, the research findings were inconsistent and varied withthe source of the pomace and the type of animals studied.

Famuyima and Ough64 determined the dry matter digestibility of severalvarieties of grape pomace in cows, sheep, and goats, and the effect of thetannin level in pomace on digestibility. The digestibility values obtained ingrape pomace (26% to 39%) are lower than alfalfa hay (69%) or Sudan grass(65%), suggesting that when grape pomace is included in beef cattle feed ata finishing rate of 20%, there is no effect on daily weight gain or finishedbody composition. Ferreira et al.68 studied the effects of dietary inclusion ofgrape pomace, as a replacement for alfalfa hay at the rates of 0, 100, 200, and300 g/kg total weight, on digestive and growth traits and on food conversionefficiency in growing rabbits. The study concluded that alfalfa hay may bepartially replaced by grape pomace as a fiber source, however, the gain:foodratio is impaired, as grape pomace inclusion increases, mainly due to areduction of the apparent digestibility of protein, since the carbohydratefraction (starch and fiber) was unaffected. Grape pomace had an estimateddigestible energy of 0.83 that of alfalfa hay.

Raspberry pomace with added rice hulls was also evaluated as a feed-stuff by means of a balance trial with pigs, and a balance and growth trialwith rats.65 The nutritive value of raspberry pomace for monogastric animalswas found to be very low. Although raspberry pomace had a low digestibleenergy content (6.26 MJ/kg) and digestible protein (1.5%), the results with



rats suggested that an inclusion level of up to 20% in a balanced diet wouldnot markedly affect the growth rate of growing finishing pigs.

Martin-Carron et al.65 fed male Wistar rats a standard diet supplementedwith 10% grape pomace over an 8-week period. The grape pomace-fed ratsshowed higher fresh and dry stool weights and increased fat, protein, andmineral excretion in feces as compared to the control group. Sixty-eightpercent of soluble polyphenols were absorbed in the gastrointestinal tract,while almost all (99%) of the insoluble polyphenols were excreted under-graded in feces, improving the high bulking capacity of dietary fiber. Nielsenand Hansen67 recently examined the effect of grape pomace on milk yield,milk composition, and cell counts in dairy cattle by allocating Danish RedHolstein dairy cows to diets supplemented with 4.5 g grape pomace per cowper day. Significant differences in milk yield were not observed and grapepomace had no effect on cell counts. It was concluded that inclusion of asmall amount of grape pomace as a feed additive does not increase proteinyield when added to a high protein diet in lactating cows.

In summary, the use of grape and other berry pomace as an animal feed islimited because of its low protein content. However, certain types of berry pom-ace may have good potential due to their other unique functions. For example,cranberry pomace has been commercially prepared as an ingredient in dog foodas a fruit source (Aliments Alternatifs 2000, Sainte-Helene-de- Bagot, Quebec,Canada). Cranberry pomace was used based on two factors: few pesticides aresprayed during cranberry growth, and because of cranberry’s well known benefitin urinary tract infection, as many dogs suffer from these types of infections.

14.6 ConclusionA wide range of value-added products may be recovered from berry fruit pro-cessing biowaste. Among different berry crops, grape pomace contributes thelargest portion. Berry pomace is currently less utilized compared with other fruitpomace, such as citrus and apple pomace, which are industrially used for pectinproduction. Thus there is a great need for research into the utilization of smallfruit pomace, especially in the area of converting it into value-added bioproducts.

The exploitation of by-products from berry fruit processing as a sourceof functional compounds and their food and nonfood applications is a prom-ising field that requires interdisciplinary research with food technologists,food chemists, nutritionists, toxicologists, and processing engineers. Futureresearch needs and challenges include

• Technologies for improving the extraction efficacy of functional com-pounds from berry pomace and specific analytical methods for thecharacterization and quantification of organic micronutrients andother functional compounds.

• Assessment of the bioactivity, bioavailability, and toxicology of phy-tochemicals extracted from berry pomace by in vitro and in vivo studies.

• Development of methods for complete utilization of by-productsresulting from berry processing on a large scale and at an affordable cost.



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411

Index

1-methylcyclopropene, 2812,2-azino-bis(3-ethylbenzthiazoline-6-

sulphonic) acid.

See

ABTS2,2-diphenyl-1-picrylhydrazyl.

See

DPPH2-phenylbenzopyrylium, 1143-feruolyquinic acid, in blackberries, 753-

p

-coumaroylquinic acid, in blackberries, 754-acetylarabinoside, in red raspberries, 764-acetylxyloside, in red raspberries, 764-arabinoside, in red raspberries, 764-desmethylsterols, 985-caffeoylquinic acid.

See

Chlorogenic acid

A

ABTS, 96Accelerated solvent extraction, 393Acetic acid, use of to control post harvest

decay, 269Acid content, 210, 373

designing thermal processes based on, 338–339

Acid surfactants, control of microbial pathogens using, 252

Acid-resisting lacquer, 354Acidity, of blackberries, 67

Actinidia arguta,

14.

See also

Hardy kiwifruit

Actinidia deliciosa

cv. Hayward, 14.

See also

Kiwifruit

ADF, from grape pomace, 396–397Africa

red raspberry production in, 9strawberry production in, 7

Agitating atmospheric cookers, 355Aglycones, 74, 114Air-blast freezers, 298Alkaline compounds, control of microbial

pathogens using, 252

Aloe vera gel, edible coating based on, 280

Amelanchier alnifolia

Nutt., 15Anaerobic microorganisms, design of

thermal processes to target, 338–339Ananasnaya, 14–15.

See also

Hardy kiwifruitgrowth and development, 24

Animal feed, use of berry pomace for, 405–406

Annual production systems, strawberry production using, 7, 25–26

Anthocyanidins, 114, 150antiproliferation effects of, 130glycosylation and acylation of, antioxidant

capacity and, 127structure of, 79, 115

Anthocyanins, 57, 74, 79–85, 158–159, 210–211

accumulation of in ripening fruit, 122–123acylations of, 116analysis of in berries, 115–116antioxidant activities of, 150bioavailability of, 131–132changes in after harvesting, 212–213composition of in berries, 117–120contents of in common berry fruits, 90decrease in content postharvest, 217degradation of in jam and jelly processing,

384effect of cultivation techniques on content

of, 166effect of heat on, 125effect of maturity on content of in berries,

168–169effect of on LDL, 131effect of postharvest treatment on levels of

in berries, 173–174effect of storage conditions on content of

in berries, 170

5802_C015.fm Page 411 Wednesday, April 18, 2007 3:46 PM


extraction of pigments from berry pomace, 392–393

glycosylations of, 116health benefits of, 126–132in black raspberries, 89in blackberries, 92in blueberries, 92in strawberries, 91, 153–154in

Vaccinium

sp., 155–156levels of in berries, 106–115monitoring composition of, 133potential use of for treating diabetes

and obesity, 131stability of, factors that favor, 123use of as colorants, 133

Anthracnose, control of using

Trichoderma,

281Antimicrobial agents, incorporation into

edible coatings for berries, 279–280Antioxidant capacity

contribution of flavonoids to, 96–97reduction of postharvest, 218–220relationship with phenolic classes, 96

Antioxidant dietary fiber.

See

ADFAntioxidant vitamins, 93Antioxidants, 264.

See also

Phytochemicalshealth benefits of, 126–127in berry fruit pomace, 391–392in blackberries, 210in fruits and vegetables, 189in strawberries, 63role of in prevention of cardiovascular

disease, 195Antiproliferative effects of berries, 128–129Appert, Nicholas, 336Apples, antioxidant activity of, 196Arabinose, 80, 85, 114, 150Arabinoside

in blueberries, 84in red raspberries, 78

Arctic bramblephenolic acids in, 157quercetin in, 157

Aronia melanocarpa,

15

Aronia

sp.antioxidant capacity of, 163–164polyphenolic components in, 156–159

Artificial light irradiation, improvement in red pigmentation postharvest using, 173–174

Artificial sweeteners, use of in low-sugar jams and jellies, 381–382

Ascorbate, 150Ascorbic acid, 55.

See also

Vitamin Ceffect of on anthocyanins, 125effect of on color, 58

in blackberries, 67in raspberries, 67in strawberries, 63reducing loss of during storage, 216–217use of before freezing of berries, 294

Aseptic temperature processing, 355–356Asia

blackberry production in, 11cranberry production in, 13currant production in, 13–14gooseberry production in, 14highbush blueberry production in, 12red raspberry production in, 8strawberry production in, 7

Aspartame, use of in low-sugar jams and jellies, 381–382

Atmospheric gases, normal percentage of, 274

Aureobasidium pullulans,

use of as a biocontrol agent, 281

Australiahighbush blueberry production in, 12strawberry production in, 8

Autumn olive berries, lycopene in, 122, 132Auxin, effect of on ripening of strawberries,

208Avenasterols, 98

B

B vitamins, 58Baby kiwifruit, 14.

See also

Hardy kiwifruit

Bacillus pumilus,


Bacillus

sp., 248

Bacillus stearothermophilus,

338

Bacillus thermoacidurans,

338Bacterial pathogens, 234, 244–245.

See also

Pathogens

control of, 266–267Ball formula method, 336–337, 346–347, 349Batch-type driers, 320Batch-type freezing systems, 298Belarus, cranberry production in, 13Belgium, protected culture systems in, 27Belt conveyor driers, 320Berry fruits.

See also

specific berriesanthocyanin glycosides in, 81–83anthocyanins in, 106–120antioxidant capacity of, 93, 159–164antiproliferative effects of, 128–129canned

grades of, 357–358microflora in, 339

canning, 358–361operations, 351–357


Index 413

changes in pigments during processing and storage, 122–126

chemical content of, 58, 61–67proximates and carbohydrates, 53

chemoprotective properties of antioxidants in, 127

composition of, 339–340controlled atmosphere storage of,

273–276dehydration of

applications, 332–333conventional methods for, 319–327high-temperature, 315–319innovation in, 327–330nutritional and safety factors, 331quality factors, 330–331

deterioration of by pathogens postharvest, 214–215

effect of harvest maturity and cultivar on quality of, 208–212

factors affecting phytonutrient content of, 176–177 (

See also

specific factors)flavonol glycosides in, 86–87foodborne parasitic disease outbreaks

associated with, 233frozen

applications of, 308–310ensuring quality of, 304–308foodborne viral disease outbreaks

associated with, 236–237market of, 292nutrients of, 295–296

grading of, 304–305, 357–358growth and development, 16–24jams and jellies

applications of, 385federal standards for, 368–369low-sugar, 379–382manufacture of, 375–378principles of processing, 370–373procedures for making, 373–375

marketing channels for, 4maturity, variations in phytochemical

content of due to, 167–169microbial safety concerns of, 232–238mineral content in, 60nonanthocyanin-containing, pigments in,

120–122ORAC values for, 94pH value of, 238phenolic composition of, 74–88phenolic content of, 89–97phytochemical content of, effect of

environmental conditions on, 164–167pigments, 57–58 (

See also

Anthocyanins)

health benefits of, 132potential applications of, 133–135

postharvest diseases in, 265–267postharvest handling of, 283

effect of on phytonutrient levels, 169–175

preparation of for freezing, 296–297preparation of for jams and jellies, 374–375process by-products of (

See also

Pomace)properties of, 388–392

processing of in boiling water, 362production systems, 24–45ripening of, postharvest changes

associated with, 56shelf life extension of, 264sources of contamination of, 239–240tannins in, 76–79utilized production value of, 232vitamin content in, 59worldwide production of, 5–16 (

See also

specific berries)

Ò-carotene, 57Betalains, 120, 122Betanin, 122Bilayer coatings, 279Bilberries

inhibition of colon cancer cells by, 130inhibition of leukemia cells by, 130quercetin in, 158use of as dietary supplements, 134use of for treatment of eye health, 131

Bioavailabilityof anthocyanins, 131–132of phytochemicals, 196–199

Biocomposites, 404Biocontrol

control of microbial pathogens using, 253–254

extension of shelf life using, 281Black chokecherries

anthocyanins in, 114antioxidant capacity of, 163–164quercetin in, 120

Black color, levels of anthocyanins and, 114Black currants.

See also

Currantsanthocyanins in, 114, 159antioxidant capacity of, 163canning of, 359flavonols in, 120production systems for, 42quercetin in, 158worldwide production of, 13–14

Black raspberries.

See also

Raspberriesanthocyanins in, 84, 89, 114, 158antioxidant capacity of, 162–163



effect of maturity on phytochemical content of, 167

ORAC values for, 93phenolics in, 89production systems for, 32reduction of tumor formation due to, 130seeds, applications of, 399–400worldwide production of, 9

Black widow spiders, infestation of berries by, 266

Blackberriesanthocyanins in, 80, 114, 158antioxidant capacity of, 162–163canning of, 358–359catechin in, 88chemical composition of, 66–67color development of, 209effect of maturity on phytochemical

content of, 167ellagitannins in, 78–79flavonols in, 85, 157foodborne pathogens associated with, 234freezing, effect of on berry pigments, 126growth and development of, 18–19ORAC values for, 95phenolic acids in, 75, 157phenolics in, 92polyphenolics in cultivars of, 158potential use of as pain reliever, 131procyanidins in, 87production systems for, 32–36secoisolariciresinol in, 97seeds, applications of, 399–400soluble solids in, 66–67, 123wild, 9worldwide production of, 9–11

Blanching, 294Blueberries

anthocyanins in, 84, 155–156bog, quercetin in, 120canning of, 359color development of, 209effect of growing region on phytochemical

composition of, 164–165effect of growing season on phytochemical

composition of, 165effect of maturity on phytochemical

content of, 168effect of storage on phytonutrient

composition of, 170effect of superatmospheric oxygen on

antioxidant levels of, 172flavonoids in, 155flavonols in, 85, 87growth and development, 20–21

inhibition of colon cancer cells by, 130low-temperature thermal dehydration of,

325–326market value of, 134ORAC values, 95, 97, 161–162phenolic acids in, 76, 91, 154phenolics in, 92–93pomace from, phenolics from, 394–395postharvest changes in, 212–215, 218–220postharvest cooling of, 270–271procyanidins in, 87production systems for, 36–39quinic acid in, 340sterols in, 98use of as dietary supplements, 134use of to improve short term memory, 131wild species of, 11worldwide production of, 11–13

Blueberry maggots, 266Bog whortleberries

flavonols in, 155phenolic acids in, 154quercetin in, 120

Botrytis cinerea,

214, 234, 253, 266–267control of using dimethoxybenzoic acid

dip, 269control of with sulfur dioxide, 268use of antimicrobial coatings to protect

against, 279–280Boysen hybrid, 19Boysenberries

anthocyanins in, 159antioxidant capacity of, 162–163phenolic acids in, 157seeds, applications of, 399–400

Bragg harvesting machine, 39Breakfast cereals, use of dried berry fruits in,

332British Columbia, highbush blueberry

production in, 12Bromine, control of microbial pathogens

using, 252By-products of berry processing, properties

of, 388–392

Byssochlamys,

339

C

C-reactive protein, 195Caffeic acid

antioxidant activities of, 149bioavailability and metabolism of, 197in blackberries, 75in blueberries, 76in red raspberries, 75


Index 415

in strawberries, 74in

Vaccinium

sp., 154Calcium, 58

edible coating based on, 280in strawberries, 63

Calcium binding, 213Calcium gluconal.

See

CGCalicivirus, 234California

blackberry production in, 10red raspberry production in, 9strawberry production in, 7

Campersterol, 98Canada

cranberry production in, 13hardy kiwifruit production in, 14highbush blueberry production in, 12lowbush blueberry production in, 12perennial production systems in, 27red raspberry production in, 9strawberry production in, 7

Cancereffect of diet on risk of, 187–189role of phytochemicals in prevention of,

190–193Cane burning, 29Caneberries.

See also

specific berriesantioxidant capacity of, 162–163production value of in U.S., 232

Canningoperations, 349–357principles of, 337–347

early, 336–337Capillary flow during dehydration, 317–318Carbohydrates, 54

chemical content of in berries, 53Carbon dioxide, 215

effect of on antioxidant capacity of berries, 167

effect of on firmness of berries postharvest, 213

effect of on phytonutrient content of berries, 171–172

use of in controlled atmosphere storage, 273–276

use of in liquid immersion freezing, 302Carcinogenesis, 127Cardiovascular disease, 126

effect of diet on risk of, 187–189protective effects of berry pigments, 132protective effects of phenolics, 130–131role of phytochemicals in the prevention

of, 192–195Carotenoids, 57, 120

contribution of to berry pigment, 122

Casuaricitinin blackberries, 78in strawberries, 78

Catechin, 150bioavailability and metabolism of, 197–198in blackberries, 88in

Vaccinium

sp., 154–155Cell wall

components, 56–57composition

changes in as quality factors for strawberries, 65

changes in raspberries, 67deterioration and softening, 211–212rupture of during freezing, 294–295

Cellophane, use of for packing of dried berries, 331–332

Cellulase activity, 212Cellulose, 56

use of derivatives as edible coatings, 279Central America

blackberry production in, 10strawberry production in, 8

CG, 303Chemical contaminants, 239Chemoprotective properties of berry

antioxidants, 127Chester Thornless blackberry cultivar, 9.

See also

Semierect blackberriesChile

blackberry production in, 10cranberry production in, 13hardy kiwifruit production in, 14highbush blueberry production in, 12projected growth of blackberry production

in, 11red raspberry production in, 8

Chilling injuries, 272China

black raspberry production in, 9blackberry production in, 11, 34highbush blueberry production in, 13projected growth of blackberry production

in, 11Chitinous material, use of as edible coatings

on berries, 279Chitosan coatings, 279–280Chlorine

control of microbial pathogens using, 252use of to control bacteria, 244use of to control post harvest decay, 269

Chlorogenic acidantioxidant activities of, 149bioavailability and metabolism of, 198in blackberries, 75



in blueberries, 76in red raspberries, 75in strawberries, 74in

Vaccinium

sp., 154Chlorophylls, contribution of to berry

pigments, 120Chokecherries, 15

anthocyanins in, 159antioxidant capacity of, 163–164content of proanthocyanidins in, 120inhibition of colon cancer cells by, 130phenolic acids in, 157quercetin in, 158

Cinnamic acids, antioxidant capacity and, 127

Citric acid, 55, 339

Clostridium botulinum,

275, 279, 336design of thermal processes to target,

338–339thermal process adequacy and, 343

Clostridium thermosaccolyticum,

338Cloudberries

antimicrobial activities of hydrolysable fractions of, 132

phenolic acids in, 157quercetin in, 157

Cocktail kiwi, 14.

See also

Hardy kiwifruitCold pressing, 124Cold storage, 269–273

recommended conditions for, 272

Colletotrichum acultatum,

214

Colletotrichum gloeosporioides,

214Color, importance of, 114Colorants, use of berry pigments as, 133–134Compost, effect of on phytochemical

composition of berries, 165–166Composting, use of berry processing waste

for, 404–405Concord grape juice, inhibition of

(DMBA)-DNA by, 130Conduction, 321–322Consumers, microbial safety and the role of,

249–250Containers, 263.

See also

Packagingair circulation in, 247canning, 353–354

coding of, 355exhausting, 354

field packing, 38sanitation issues with, 234

packaging of dried fruit, 332plastic-lined, 272–273sanitized, 244use of sulfur dioxide pads in, 268

Contamination, sources of, 239–240

Continuous agitating atmospheric cookers, 355

Continuous driers, 320–321Continuous water bath pasteurizers, 355Controlled atmosphere storage, 220, 263,

273–276benefits of, 275effect of on phytonutrient content of

berries, 171–173effects of, 278

Controlled stresses, enhancing nutritional content postharvest with, 220

Convection, 321–322Conventional cultivation, effect of on

phytochemical composition of berries, 165–167

Cooling, 262–263, 269–273following thermal processing, 356–357

Costa Rica, blackberry production in, 10Cranberries

American, anthocyanins in, 116antioxidant capacity of, 161canning of, 360chilling injuries, 272effect of maturity on phytochemical

composition of, 168effect of storage on phytonutrient

composition of, 170flavonols in, 155growth and development, 21–22juice, benefits of to female urinary tract

health, 132phenolic acids, 154pomace from

biodegradable packaging film from, 403–404

chemical composition of, 389–390extraction of phenolic compounds from,

394production systems for, 39–41role of in prevention of cardiovascular

disease, 195small, quercetin in, 120use of as dietary supplements, 134worldwide production of, 13

Cranberry powder, applications of, 134–135Cranberry-lingonberry juice, benefits of to

female urinary tract health, 132Crowberries, quercetin in, 158Cryogenic freezers, 301–302Cryoprotectants, 303Cryostabilizers, 303Cultivars.

See also

specific berry typesantioxidant capacity affected by, 159–164black raspberries, 32


Index 417

blackberry, 9anthocyanin differences in, 80, 84erect, 34–35semierect, 33–34trailing, 35–36

blueberry, 11anthocyanins in, 84highbush and rabbiteye, 36–38phenolics in, 92–93

color differences due to, 57cranberry, 39currants, 42effect of on fruit quality of berries, 208–212effect on chemical composition of berries,

51gooseberry, 42red raspberry, 28

primocane fruiting, 31strawberry, 7–8, 16

chemical compositions of, 64use of in annual production systems,

25–26use of in perennial production systems,

27use of in protected culture systems, 27

variations in anthocyanins, 114, 152Cultivation techniques, effect of on


Currantsgrowth and development, 22–23production systems for, 42–43worldwide production of, 13–14

Cyanidin, 114antioxidant capacity and, 127in

Vaccinium

sp., 155–156Cyanidin 3-glucoside, 114

in strawberries, 153Cyanidin derivatives

in blackberries, 80in blueberries, 84in raspberries, 84

Cyclamates, use of in low-sugar jams and jellies, 381–382

Cyclospora cayetanensis,

234

D

D

value, 340–341temperature dependence of, 342

Day-neutral cultivars, 26Decay

control of, 265–269due to pathogens, 214–215

Decimal reduction time.

See

D

value

Deerberries, antioxidant capacity of, 162Dehydration, 314

control of quality and nutritional losses during, 330–332

conventional methods for, 319–327high-temperature, 315–319innovation in, 327–330

Dehydroascorbic acid, 216Delphinidin, 114

in blueberries, 84in

Vaccinium

sp., 155–156Diet, health benefits of plant-based foods in,

187–189Dietary fiber, 58

sources of, 395–397Dietary supplements, use of

anthocyanin-rich berry extracts as, 134

Dihydroflavonol, antioxidant activities of, 149

Dimethoxybenzoic acid, use of to control post harvest decay, 269

Direct sales, microbial safety and, 248Disease, control of, 265–269Distribution, microbial safety and, 246–248(DMBA)-DNA, 130DPPH, 96Dried fruits

applications of, 332–333processing of, 326–327

Drip loss, 295use of edible coatings to control, 303–304

Drum drying of berries, 321Dry harvesting, cranberries, 40Drying phenomena in dehydration, 318–319

E

Early cropping, blueberries, 37Ecuador, blackberry production in, 10Edible coatings, 278–280

use of to control drip loss during freezing, 303–304

Egypt, strawberry production in, 7Elderberries, 15

antioxidant capacity of, 163–164phenolic acids in, 157potential use of as pain reliever, 131production systems for, 43–44quercetin in, 120use of as dietary supplements, 134

Ellagic acid, 74, 157contents of in common berry fruits, 90derivatives of, 76–79in black raspberries, 89



in blackberries, 92in strawberries, 152structure of, 77

Ellagitannins, 74, 76–79in blackberries, 158in strawberries, 91, 152structure of, 77

Enterodiol, 97Enterolactone, 97Environmental conditions

effect of on strawberry quality, 63–64phytochemical content of berries and,

164–167Enzymatic liquefaction, 124Enzymes, 55–56

changes due to, 56design of thermal processes to target,

338–339inactivation of before freezing, 294pectolytic, addition of during juice

processing, 124phase II, induction of by anthocyanin-rich

extracts, 130thermal inactivation time of, 341–342

Epicatechinbioavailability and metabolism of, 197–198in red raspberries, 88in

Vaccinium

sp., 154–155Equilibrium relative humidity.

See

ERHErect blackberries.

See also

Blackberriesproduction systems for, 34–35

ERH, 316

Escherichia coli,

230–232, 234, 252, 254, 266–267

survival of in juices and purees, 235use of antimicrobial coatings to protect

against, 280Esters, 74Ethanol

effect of on strawberries postharvest, 222production of from berry pomace,

402–403Ethylene, effect on ripening of berries, 208Eugenol, 282Europe

blackberry production in, 10cranberry production in, 13currant production in, 13–14gooseberry production in, 14highbush blueberry production in, 12red raspberry production in, 8strawberry production in, 5–7

Evaporative cooling, 271Evergreen huckleberries, 15Exhausting step of canning, 354

F

Far-red light, effect of on levels of anthocyanins in berries, 173

FDA, 231Center for Food Safety and Applied

Nutrition, 240juice label warning requirements, 238

Ferric reducing antioxidant power.

See

FRAPFertigation, 27Fertilizer monitoring, 242Fertilizers, from berry processing waste,

404–405Ferulic acid

in blackberries, 75in blueberries, 76in red raspberries, 75in strawberries, 74in

Vaccinium

sp., 154Fibers, sources of in berry pomace, 395–397Field sanitation, 243Firmness, of berries after harvesting, 213Flavan-3-ols, 55, 74

contribution of to berry pigments, 120in strawberries, 153in

Vaccinium

sp., 154–155Flavonoids, 74, 120

biological activities of, 148–149contribution of to antioxidant capacity,

96–97structures of, 79

Flavonols, 74, 85–87antioxidant activities of, 149contents of in common berry fruits, 90contribution of to berry pigments, 120effect of cultivation techniques on content

of, 166in blackberries, 92, 158in strawberries, 92, 153in

Vaccinium

sp., 154–155role of in prevention of cancer, 190structures of, 79

Flavor, effect of soluble solids and titratable acidity on, 209–210

Flavylium salts, 114Floricanes

blackberry, 18–19raspberry, 17–18

Florida, strawberry production in, 7Fluidized bed driers, 320Fluidized bed freezers, 301Folate, 58Folin Ciocalteu reagent, 89Food safety, strategies and programs,

240–242


Index 419

Foodborne pathogens, 230–232Forced-air cooling, 270Forced-air ventilation, 271–272Formula methods for thermal process

calculation, 346–347Formulated foods, use of dried berry fruits

in, 332–333

Fragaria ananassa,

152

Fragaria chiloensis,

16, 152

Fragaria

sp., antioxidant activity of, 160

Fragaria vesca

L., 16, 153

Fragaria virginiana,

152

Fragaria

x

ananassa

Duch., 16France

hardy kiwifruit production in, 14protected culture systems in, 27

FRAP, 96, 218Free radicals, 126Freeze-drying, 319, 322Freeze/thaw cycles, 307–308Freezing

effect of on berry pigments, 126innovations in, 303–304methods for, 296–302preservation of berries by, 292principles of, 293–296rapid, 305rate, factors affecting, 293

Frigo, 26Fructose, 54, 150

in blackberries, 66Fruit preserves, effect of processing for on

anthocyanins, 125Fruit softening, 56, 211–212Fruits

antioxidant activity of, 189phenolic content of, 188

Functional foods, 134Fungal diseases, control of, 266–267Furford picker, 41

G

Galactose, 80, 85, 114, 150Galactosides, in blueberry cultivars, 84Gallic acid

in blackberries, 75in blueberries, 76in red raspberries, 75in strawberries, 74in

Vaccinium

sp., 154structure of, 77

GAP, 240–241, 246, 269preharvest, 243

Gel formation, role of pectin in, 372–373

General method for thermal process calculation, 345–346

Gentisic acidin blackberries, 75in blueberries, 76

Germany, hardy kiwifruit production in, 14

Glucose, 54, 80, 85, 114, 150in blackberries, 66

Glucosidesin blueberries, 84in red raspberries, 85

Glucuronide, in red raspberries, 85Glutathione-S-transferases.

See

GSTGlycosides, 74GMP, 239, 246

areas addressed by, 240–241Good agricultural practices.

See

GAPGood manufacturing practices.

See

GMPGooseberries

anthocyanins in, 159canning of, 360–361growth and development, 22–23production systems for, 42–43quercetin in, 158worldwide production of, 13–14

Gradescanned berries, 357–358frozen berries, 304–305

Grape kiwi, 14.

See also

Hardy kiwifruitGrape seeds

applications of, 398–399use of as substrates for enzymes, 402

Grapescontrol of post harvest decay of, 268inhibition of colon cancer cells by, 130pomace from

chemical composition of, 389–391extension of shelf life of using gamma

irradiation, 395use of for fertilizer, 404–405

Gray mold, 266–267.

See also

Botrytis cinerea

Green currantsflavonols in, 120inhibition of human carcinoma cells by,

132Growing location

effect on chemical composition of berries, 51

effect on phytochemical composition of berries, 164–165

Growing season, effect of on phytochemical composition of berries, 165

GST, 130Guatemala, blackberry production in, 10



H

HACCP, 231, 241–242, 246, 269Hand harvesting

blueberries, 37red raspberries, 30–31

Handling conditions, effect on chemical composition of berries, 52

Hardy kiwifruit, 14–15growth and development, 24production systems for, 44–45

Harvest maturity.

See

MaturityHarvesting, 25, 262–263

changes after, 212–223effect on chemical composition of berries, 52mechanical, red raspberries, 30pigment changes during, 122–123safe practices for, 243–245

Hayward, 14.

See also

KiwifruitHazard Analysis and Critical Control Point.

See

HACCPHeadspace, 352Heat penetration test, 343–345Heat transfer in dehydration, 317, 321–322Heat treatment, 218

effect of on berry pigments during processing, 124–125

process calculations for, 347–349use of in canning, 336–337

Hedgerow systems, red raspberries, 28HELP, 329Hemicellulose, 56

metabolism of, 211Hepatitis A, 234Hexahydroxydiphenic acid.

See

HHDPHexanal formation, inhibition of, 127HFCS, 303HHDP, 76High fructose corn syrup.

See

HFCSHigh methoxyl pectin.

See

HMPHigh performance liquid chromatography.

See

HPLCHigh-intensity electrical field pulse.

See

HELPHigh-speed mechanical vacuum exhausting,

354Highbush blueberries.

See also

Blueberriesphenolic acids in, 154production systems for, 36–38use of 1-methylcyclopropene to slow

postharvest ripening, 281worldwide production of, 12–13

Hill plasticulture cultivation system, effect on phytochemical content of berries of, 166–167

Hill systems, red raspberries, 28–29

Hippuric acid, bioavailability and metabolism of, 197

HMP, 303Hot air drying of berries, 320–321

drying line, 322, 325quality factors, 330–331

HPLC, 133analysis of phenolic acids using, 74characterization of anthocyanins using, 80,

114, 116identification of ellagitannins and ellagic

acid using, 76identification of flavonols using, 85

HTST pasteurization, 356Huckleberries, 11, 15.

See also

Blueberriesblack, flavonols in, 155phenolic acids, 154

Human pathogens, contamination of fruits by, 239

Humidity, 271–272Hungary, projected growth of blackberry

production in, 11Hunter “a*” value, 125Hydrocooling, 271Hydrogen peroxide, control of microbial

pathogens using, 252Hydrolytic enzymes, production of on grape

pomace substrate, 402Hydroxybenzoic acids, 74

in blackberries, 75in blueberries, 76structures of, 75

Hydroxycinnamate chlorogenic acid, in blueberries, 92

Hydroxycinnamic acids, 74in blackberries, 75in blueberries, 76structures of, 75

I

Ice crystals, 305–306Icing, 271IDF, from grape pomace, 395–397Impregnation, 327, 329–330Induced resistance, 254Inflammation, role of in cardiovascular

disease, 195Inhibition of hexanal formation, 127Insects

infestation of berries by, 265–267postharvest control of, 273

Insoluble dietary fiber.

See

IDFIodine, control of microbial pathogens using,

252


Index 421

Iron, in strawberries, 63Irradiation

extension of shelf life using, 281low-dose

control of decay using, 215control of microbial pathogens using,

252–253nutritional losses due to, 217

Isorhamnetin, 122Italy, hardy kiwifruit production in, 14

J

Jamsapplication of, 385effect of processing for on anthocyanins,

125, 384federal standards for, 368–369low-sugar, 379–382manufacture of, 375–378principles of processing, 370–373procedures for making, 373–375quality factors for, 383–384reduced pressure processing for, 382

Japan, highbush blueberry production in, 12–13Jasmonic acid, 167Jellies

application of, 385effect of processing for on anthocyanins, 384federal standards for, 368–369low-sugar, 379–382manufacture of, 377, 379principles of processing, 370–373procedures for making, 373–375quality factors for, 383–384reduced pressure processing for, 382

Jostaberries, 23, 43Juice

berrybenefits of to female urinary tract health,

132preparing an HACCP plan for, 246production of, 245

contaminated, recall data on, 234processing, 124unpasteurized, foodborne outbreaks

linked to, 232use of in spray drying of berries, 321

Juneberries, 15

K

Kaempferol, 85antioxidant activities of, 149in blackberries, 85, 157

in blueberries, 87in strawberries, 153

Kiwifruit, 14–15Klason lignin, in grape pomace, 395–396

L

Laccase, production of by

Trametes hirsuta,

402

Lambertianin-Cin red raspberries, 76structure of, 78

LDL, 57biological effect of flavonoids on, 149effect of sterols on, 98inhibition of by phenolics, 130–131inhibition of hexanal formation, 127oxidation of, 193–195role of phytochemicals in concentrations

of, 192–195

Legionella pneumophilia,

249Legionnaire’s disease, 249

Lentinus edodes,

production of polygalacturonase by, 401–402

Lethality, 342–343Light exposure

effect of on anthocyanins, 125influence of on anthocyanin biosynthesis

in plants, 173Lignans, 97Lignin, in grape pomace, 395–396Lingonberries

antioxidant capacity of, 161–162effect of maturity on phytochemical

content of, 167–168flavonols in, 155growth and development, 23–24production systems for, 43worldwide production of, 14

Linolenic acid, in seed oils, 399–400Lipid coatings, 279Liquid icing, 271Liquid immersion freezing, 301–302Liquid nitrogen, use of in liquid immersion

freezing, 302Liquid phase diffusion during dehydration,

317–318

Listeria monocytogenes,

234, 239, 248, 252, 266–267

Logan hybrid, 19Loganberries, canning of, 361Long-case raspberries, 32.

See also

RaspberriesLow density lipoproteins.

See

LDLLow methoxyl pectins, use of in low-sugar

jams and jellies, 379–381



Low-temperature thermal dehydration, 325–326

Lowbush blueberries.

See also

Blueberrieschlorogenic acid in, 154cultural management of, 38–39phenolics and anthocyanins in, 93worldwide production of, 11–12

Lutein, 57benefits to eye health of, 132

M

M

-coumaric acidin blackberries, 75in blueberries, 76

Machine harvesting.

See

Mechanical harvesting

Magnesium, 58in strawberries, 63

Maillard reactions, control of, 316Maine, lowbush blueberry production in, 12Malic acid, 55Malvidin, 114

in blueberries, 84, 155Marionberries

anthocyanins in, 158antioxidant capacity of, 162–163effect of cultivation techniques on

phytochemical composition of, 166phenolic acids in, 157

Marketing channels, 4Mass transfer in dehydration, 317–318

impregnation and, 329–330osmotic drying, 328–329

Massachusetts, cranberry production in, 13Matairesinol, 97Matted row cultivation system, effect on

phytochemical content of berries of, 166–167

Maturity.

See also

Ripeningeffect of on fruit quality of berries, 208–212effect of on phytonutrient content of

berries, 176–177variations in phytochemical content of

berries due to, 167–169Mealybugs, 266Mechanical harvesting, 262–263

blueberries, 37–38red raspberries, 30

Mediterranean diet, health benefits of, 188Menthol, 282Metabolism, of phytochemicals, 196–199Methyl bromide, use of to control insect

pests, 266Methyl jasmonate, 167, 169, 282

effect of on antioxidant activities of berries, 174–175

effect of on strawberries postharvest, 222Methylquercetin-pentose, in red raspberries,

85

Metschnikowia fructicola,


Mexicoblackberry production in, 10, 34–35highbush blueberry production in, 12projected growth of blackberry production

in, 11strawberry production in, 7

Microbial changes during freezing, 295Microbial destruction kinetics, 340–343Microbial growth, sugar concentration in

jams and jellies and, 371–372Microbial safety

concerns, 230–238direct sales, 248intervention technologies for ensuring,

250–254retail handling, 248–249role of consumers in ensuring, 249–250strategies for ensuring, 242–246transportation and distribution, 246–248

Microbiological contaminants, 239Microflora, in canned berry fruits, 339Microorganisms

designing thermal processes targeting, 338–339

osmotic tolerance of, 371–372thermal resistance of, 339

Microwave dehydration, 322combination of with osmotic drying, 329

Microwave/vacuum dehydration processes, 329

quality factors, 331Middle East, strawberry production in, 7Minerals, 58, 60Modified atmosphere storage, 215, 220

effect of on phytonutrient content of berries, 171–173

packaging, 276–278effect of, 278

Moisture loss, 271Moisture migration, 307Molds

blue, 268gray, 234, 266 (

See also

Botrytis cinerea

)use of low dose irradiation to control,

281in canned berry fruits, 339

Montenegro, red raspberry production in, 8Morocco, strawberry production in, 7


Index 423

Myricetin, 85, 120, 122, 158in blueberries, 85in strawberries, 153in

Vaccinium

sp., 154–155

N

Navaho blackberry cultivar, 9.

See also

Erect blackberries

Near-infrared spectroscopy.

See

NIRSNeochlorogenic acid, in blackberries, 75

Neosartorya fischeri,

351New Brunswick, lowbush blueberry

production in, 12New Zealand

blackberry production in, 11hardy kiwifruit production in, 14highbush blueberry production in, 12red raspberry production in, 9

Niacin, 58NIRS, use of for sorting berries for canning,

352Nitrogen fertilization

impact of on growth of blackberries, 33impact of on growth of red raspberries, 29

North America.

See also

Canada; Mexico; United States

red raspberry production in, 28Northern highbush blueberries.

See also

Highbush blueberries

production systems for, 36–38Nova Scotia, lowbush blueberry production

in, 12Nutraceuticals, 134Nutrients of frozen berries, 295–296Nutrition

effects of dehydration on, 331enhancing postharvest, 220–223jams and jellies, 384loss of during postharvest handling and

storage, 215–220

O

O

-coumaric acid, in blueberries, 76Oceania

blackberry production in, 11highbush blueberry production in, 12red raspberry production in, 9strawberry production in, 8

Off-season production systems, summer-bearing red raspberries, 31–32

Oligomeric proanthocyanidins.

See

OPCsOPCs, health benefits of, 398ORAC assays, 93–96

ORAC valueseffect of maturity on, 168–169effect of storage conditions on, 171hydrophilic, 95relationship of with anthocyanin content,

127Oregon

berry production in, 232blackberry production in, 10gooseberry production in, 14hardy kiwifruit production in, 15red raspberry production in, 9strawberry production in, 7

Organic acids, 55, 339–340Organic cultivation, effect of on


Osmotic dehydration, 328–329quality factors, 331

Oxidative changes, reduction of in freezing process, 294

Oxidative stress, 93, 191Oxygen, concentrations of in controlled

atmosphere storage, 273–274Oxygen radical absorbing capacity assay.

See

ORAC assays

Ozone, 174control of microbial pathogens using, 252

P

p-coumaric acidantioxidant activities of, 149in blackberries, 75in blueberries, 76in red raspberries, 75in strawberries, 74, 152in Vaccinium sp., 154

p-coumaroyl glucose, antioxidant activities of, 149

p-hydroxybenzoic acidin blackberries, 75in red raspberries, 76in strawberries, 74in Vaccinium sp., 154

Packaging, 263biodegradable materials from berry

pomace, 403–404composite, 356dried products, 331–332for frozen berries, 298

limiting moisture loss and gas transfer with, 308

types of, 299–300jams and jellies, 384–385



Packing operations, 244–245Paecilomyces, 339Parasites, 266–267Pasteur, Louis, 336Pasteurization, 342, 347

berry fruits, process calculations, 347, 349control of microorganisms in acidic fruits

with, 338techniques, 355–356

Pathogensdeterioration of berry fruit due to, 214–215effect of freezing on, 295microbial, 230–232

Pectin methyl esterase. See PMEPectin modification, 56Pectins, 211–212

effect of on quality of jams and jellies, 384in jams and jellies, 372–373low methoxyl, 379–381

Pectolytic enzymes, addition of during juice processing, 124

Pedunculaginin blackberries, 78in strawberries, 78

Pelargonidin, 114Pelargonidin 3-glucoside, in strawberries, 80,

153Penicillium expansum, control of with sulfur

dioxide, 268Peonidin, 114

in blueberries, 84in Vaccinium sp., 155–156

Perennial production systems, strawberry production using, 7, 27–28

Pergola trellises, 44Peroxidase. See PODPesticide monitoring, 242Petunidin, 114

in blueberries, 84, 155PG, 55pH

acid content, 210changes in, 307control of gel formation in jams and jellies

by, 370designing of thermal processes to target

specific levels of, 338–339effect of on thermal resistance of

microorganisms, 339Phase II enzymes, induction of by

anthocyanin-rich extracts, 130Phenolic acids, 55, 74–76, 157

antioxidant activities of, 149effect of cultivation techniques on content

of, 166

in blackberries, 92, 157use of to prevent color degradation in

juices, 124Phenolic classes, relationship with

antioxidant capacity, 96Phenolic compounds, 74

use of to control microbial pathogens, 254Phenolic polymers, in grape pomace, 395–396Phenolics

contents of in common berry fruits, 90effect of storage conditions on levels of in

berries, 170extraction of from berry pomace, 393–395in berry fruit pomace, 391–392structure of in berry fruits, 151total, in fruits and vegetables, 189

Phialophora, 339Phlorizin, bioavailability and metabolism of,

197Phosphorous, 58Physical contaminants, 239–240Phytochemicals, 74, 93, 148

antioxidant activity of, 195–196bioavailability and metabolism of, 196–199effect of environmental conditions on,

164–167health benefits of, 189–190in pomace, 389role of in prevention of cancer, 190–193role of in prevention of cardiovascular

disease, 192–195Phytohormone treatments, 220Phytolaccanin, 122Phytolaccatoxin, 122Phytonutrients

decrease in content postharvest, 217effect of postharvest handling on levels of

in berries, 169–175Phytophthora root rot, 44Pigments, 57–58, 210–211. See also

Anthocyanins; specific pigmentsextraction of from berry pomace, 392–393from anthocyanins, 106–120potential applications of, 133–135

Plant-based foods, health benefits of, 187–189PME, 56POD, 55

use of as a marker for thermal processing, 339

Pokeberries, phytolaccanin in, 122Poland

gooseberry production in, 14perennial production systems in, 27projected growth of blackberry production

in, 11


Index 425

red raspberry production in, 8strawberry production in, 6

Polygalactouronase. See PGPolygalacturonase, production of through

SSF, 401–402Polyphenol oxidase. See PPOPolyphenolics, in berry fruit pomace, 391–392Polypropylene, use of for packing of dried

berries, 331–332Polysaccharide degradation, 57Polysaccharides, use of for edible coatings,

279Polyvinyl chloride. See PVCPomace

animal feed from, 405–406antioxidant activity of, 132biodegradable packaging materials from,

403–404biofuel production of, 402–403fertilizers from, 404–405food applications of, 392–400functional compounds in, 391–392pigment production from residues of, 133properties of, 389–391seeds in, applications of, 398–400sources of, 388

Postharvestchanges associated with berry ripening, 56chemical changes, 294color differences due to handling, 57cooling, 262–263decay, 214–215

chemical control of, 268effect of on chemical composition of

strawberries, 65effect of on phytonutrient content of

berries, 176–177effect of on phytonutrient levels in berries,

169–175factors affecting quality of berries, 265nutrition loss associated with storage and

handling, 215–220Potassium, 58

in strawberries, 63Potentillin

in blackberries, 78in strawberries, 78

PPO, 55Preharvest

conditions, effect of on phytonutrient content of berries, 176–177

GAPs for berries, 243strategies for ensuring microbial safety of

berries, 242–243Preserves, federal standards for, 368

Prestorage heat treatments, 173Prime-Jim, 35Prime-Jan, 35Primocane fruiting blackberries, 35Primocane fruiting raspberries, 31Primocanes

blackberry, 18–19raspberry, 17–18suppression of, 29

Proanthocyanidins, 74, 87–88, 150from grape seeds, 398–399

Processingchanges in berry pigments during, 122–126color differences due to, 57

Procyanidinsin blackberries, 92, 158in blueberries, 92in red raspberries, 89in strawberries, 92structures of, 88

Produce Safety Initiative, 231Protected culture, strawberry production

using, 7, 26–27Protein coatings, 279Protocatechuic acid

in blackberries, 75in blueberries, 76in red raspberries, 76in strawberries, 74

Protozoan parasites, infestation of berries by, 266–267

Proximates, chemical content of in berries, 53Prudent pattern, 188Pseudomonas fluorescens, use of as a biocontrol

agent, 281Pseudomonas syringiae, 253Pulsed vacuum impregnation, 330Purple raspberries, 32PVC, use of for packing of dried berries,

331–332

Q

QR, 130Quality factors

dehydration, 330–331jams and jellies, 383–384

Quality standards, frozen berries, 304–305Quebec, lowbush blueberry production in, 12Quercetin, 85, 122

antioxidant activities of, 149bioavailability and metabolism of, 197–198contribution of to berry pigments, 120in blackberries, 157in blueberries, 85



in red raspberries, 85in strawberries, 85, 153in Vaccinium sp., 154–155inhibition of human carcinoma cells by, 132role of in prevention of cancer, 190–192role of in prevention of cardiovascular

disease, 192Quinone reductase. See QR

R

Rabbiteye blueberriesphenolic acids in, 154production systems for, 36–38

Raspberriesanthocyanins in, 84antimicrobial activities of hydrolysable

fractions of, 132antioxidant capacity of, 162–163canning of, 361chemical composition of, 67color development of, 209effect of maturity on phytochemical

content of, 167, 169effect of storage on phytonutrient

composition of, 170–171effects of cultivar and storage conditions

on properties of, 221flavonols in, 157foodborne pathogens associated with, 234freezing, effect of on berry pigments, 126growth and development of, 17–18phenolic acids in, 157phenolics in, 89postharvest changes in, 212–215primocane fruiting, 31procyanidins in, 87production systems for, 28–32quercetin in, 157sanguiin H-6 in, 158seeds, applications of, 399–400soluble solids in, 67worldwide production of, 8–9

Raspberry-blackberry hybrids, 19Red currants. See also Currants

production systems for, 42quercetin in, 158worldwide production of, 13–14

Red light, effect of on levels of anthocyanins in berries, 173

Red raspberries. See also Raspberriesanthocyanins in, 84, 89, 158–159antioxidant capacity of, 162–163ellagitannins in, 76epicatechin in, 88

flavonols in, 85hydrolyzable tannins from, antioxidant

activity of, 132ORAC values for, 95phenolic acids in, 75–76, 157procyanidins in, 89seeds, applications of, 399–400summer-bearing, production systems for,

28–31worldwide production of, 8–9

Refrigeration methods, 270Renovation, 28Respiration rates, 278

effect of on storage life of berries, 208Resveratrol, in Vaccinium sp., 155Retail handling, microbial safety and,

248–249Rhagoletis mendax, 266Rhamnose, 80, 85, 150Rhizopus rot, 215, 266–267Rhizopus stolonifer, 253

control of using dimethoxybenzoic acid dip, 269

Ribes nigrum L., 13Ribes rubrum L., 13Ribes sp., 22, 42–43

antioxidant capacity of, 163polyphenolic components in, 156–159

Ribes uva-crispa L., 13Ripeness

color differences due to, 57effect on chemical composition of berries,

52postharvest changes associated with, 56

Ripening. See also Maturityeffect of ethylene on, 208pigment changes during, 122–123

Romaniacranberry production in, 13projected growth of blackberry production

in, 11Room cooling, 270Rosmarinic acid, use of to prevent color

degradation in juices, 124Rowanberries

anthocyanins in, 159antioxidant capacity of, 163–164phenolic acids in, 157

Rubus arcticus L., 17Rubus glaucus Benth., 10Rubus idaeus L., 17Rubus occidentalis L., 17Rubus sp.

antioxidant capacity of, 162–163polyphenolic components in, 156–159


Index 427

Russian Federationgooseberry production in, 14red raspberry production in, 8strawberry production in, 7

Rutinose, 80, 85, 114Rutinoside, in red raspberries, 85

S

Safety concernsdehydration, 331microbial, 230–232

Salicylic acidin blackberries, 75in blueberries, 76

Salmonella sp., 231, 234, 254, 266–267survival of in juices and purees, 235

Sambubiose, 80, 114Sambucus canadensis L., 15Sambucus nigra L., 15Sambucus sp.


Sanding, 41Sanguiin H-10, in red raspberries, 76Sanguiin H-6

in blackberries, 78in raspberries, 158in red raspberries, 76in strawberries, 78structure of, 78

Sanitation, berry handlers, 269Sanitation standard operating procedures.

See SSOPsSaskatoon berries, 15

quality losses produced by drying methods for, 323–324

Scandinavia, perennial production systems in, 27

SDF, from grape pomace, 395–397Sea buckthorn berries

antioxidant activity of, 132carotenoids in, 122inhibition of human carcinoma cells by, 132

Seaming step in canning, 355Seaweed extracts, use of as edible coatings on

berries, 279Secoisolariciresinol, in blackberries, 97Semierect blackberries. See also Blackberries

production systems for, 33–34Sensory quality, changes in postharvest,

213–214Serbia, red raspberry production in, 8Serviceberries, 15Shade cloth, 31–32

Shelf life, extension of, 264, 280–282. See also Edible coatings; Packaging; Storage

Short-day cultivars, 25Sinapic acid, use of to prevent color

degradation in juices, 124Sitosterol, 98Snack foods, use of dried berry fruits in, 332Soils, raspberry production, 28Solid-state fermentation. See SSFSoluble dietary fiber. See SDFSoluble solids, 209–210

changes in postharvest, 213–214effect of growing conditions on, 44effect of machine harvesting on, 36–37effect of nitrogen fertilization on, 29, 33in blackberries, 66–67, 123in jams and jellies, 368–369in raspberries, 67in strawberries, 63–66

Solute crystallization, 307Sophorose, 80, 114Sorbitol, use of in low-sugar jams and jellies,

381–382Sorbus sp.


South Africa, blackberry production in, 11South America

cranberry production in, 13highbush blueberry production in, 12red raspberry production in, 8strawberry production in, 8

Southern highbush blueberries. See also Highbush blueberries

production systems for, 36–38Spain, protected culture systems in, 27Spiders, infestation of berries by, 266Spiral belt freezers, 298–299Spray drying of berries, 321SSF, 391

berry pomace as a substrate for, 401–403SSOPs, 241, 246Staphylococcus sp., 248, 254

use of antimicrobial coatings to protect against, 280

Starch, use of as edible coatings on berries, 279Steam-flow exhausting, 354Sterilization, 342, 347

value, 345–346Sterols, 98Stigmasterol, 98Stilbenes, 98Storage

changes in berry pigments during, 122–126cold, extending shelf life with, 269–273



conditions, 263effect of on chemical composition of

strawberries, 65effect of on phytonutrient levels in

berries, 170–171effect on chemical composition of

berries, 52effect of respiration rate on, 208frozen, prevention of quality deterioration

during, 305temperatures, effect of on anthocyanins, 125

Strawberriesannual production systems, 25–26anthocyanins in, 80antioxidant activity of, 160canning of, 361chemical content of, 63–66controlled atmosphere storage of, 274–275cultivars, 7–8effect of auxin on ripening of, 208effect of cultivation techniques on

phytochemical composition of, 166effect of growing region on phytochemical

composition of, 164–165effect of growing season on phytochemical

composition of, 165effect of maturity on phytochemical

content of, 167–168effect of storage on phytonutrient

composition of, 170ellagitannins in, 78flavonols in, 85foodborne pathogens associated with, 234growth and development of, 16–17market value of, 134ORAC values of, 93phenolic acids in, 74–75, 152phenolics in, 91–92postharvest changes in, 212–215postharvest hydrocooling of, 271potential use of as pain reliever, 131procyanidins in, 87reduction of tumor formation due to, 130soluble solids in, 63–66, 209use of antimicrobial agents in coatings for,

279–280vitamin C loss postharvest, 216worldwide production of, 5–8

Streptococcus faecalis, use of antimicrobial coatings to protect against, 280

Stumbo’s formula method, 347, 349–350Subcritical water extraction, 393Sublimation, 307Sucrose, 54

in blackberries, 66

Sugar content, 54, 210, 340in jams and jellies, 370–372

Sugar infusion, 327–328Sulfur dioxide

use of to control insect pests, 266use of to control post harvest decay, 268use of to prevent color degradation in

juices, 124Sulfur-resisting lacer, 354Summer-bearing red raspberries. See also Red

raspberriesproduction systems for, 28–31

off-season, 31–32Sun drying of berries, 319–320Superatmospheric oxygen treatments, effect

of on antioxidant levels of berries, 172Supercooling, 293Supercritical water extraction, 393Surface disinfectants, control of microbial

pathogens using, 251–252Survivor curve, 340–341Sweet rowanberries. See also Rowanberries

antioxidant capacity of, 163–164Switzerland, protected culture systems in, 27Syneresis, 383Syringic acid, in blueberries, 76Syrups, effect of processing for on

anthocyanins, 125

T

T-bar trellises, 44T-cinnamic acid, in strawberries, 74Tannins

condensed, 87hydrolyzable, cardioprotective nature of,

132in grape pomace, 395–396

Tayberry hybrid, 19TDT, 341TEAC values, 210Temperature control, control of microbial

pathogens using, 251Tetra-Pak, 356The Netherlands

hardy kiwifruit production in, 15protected culture systems in, 27

Thermal death time. See TDTThermal exhausting, 354Thermal inactivation time. See TITThermal processing

calculations for, 345–347design of, 337–338measuring effectiveness of, 342–343process calculations for, 347–349


Index 429

Thermovinification, 124Thymol, 282TIT, 341Titratable acidity, 209–210

changes in postharvest, 213–214effect of nitrogen fertilization on, 33in raspberries, 67

Tocopherols, 58, 150Top icing, 271Trailing blackberries, production systems for,

35–36Trametes hirsuta, laccase production on, 402Transportation, 263–264, 272

microbial safety and, 246–248Tray cabinet driers, 320Trichoderma

growth of on cranberry pomace substrate, 401

use of as a biocontrol agent, 281Trolox equivalent antioxidant capacity

values. See TEAC valuesTummelberry hybrid, 19Tunnel driers, 320Tunnel freezing, 298Turkey, strawberry production in, 7

U

UGT, 130Ultra-high temperature processing, 355–356United Kingdom, protected culture systems

in, 27United States

black raspberry production in, 9blackberry production in, 10cranberry production in, 13hardy kiwifruit production in, 14highbush blueberry production in, 12lowbush blueberry production in, 12perennial production systems in, 27projected growth of blackberry production

in, 11red raspberry production in, 9strawberry production in, 7

Uridine diphosphate-glucurono-syltransferase. See UGT

USDA, 231berry grades, 304–305, 357–358

UV irradiation, 220, 282effect of on levels of red pigmentation in

berries, 173–174

V

Vaccinium angustifolium Ait., 11Vaccinium corymbosum L., 12

Vaccinium macrocarpon Ait., 13, 21Vaccinium myrtilloides Mich., 11Vaccinium myrtillus L., 11Vaccinium ovatum Pursch., 15Vaccinium oxycoccos L., 13Vaccinium sp.

antioxidant activity of, 161–162effect of growing region on phytochemical

composition of, 164–165growth and development, 20–21phenolic acids in, 154QR induction properties of, 130resveratrol in, 98

Vaccinium uliginosum L., 11Vaccinium vitis-idaea L., 23Vacuum drying of berries, 321–322Vacuum impregnation, 303Vacuum infusion, 329–330Vacuum packaging, reduction of oxidative

changes using, 294Vacuum step of canning, 354Value-added berry products, acidity of, 238Vanillic acid

antioxidant activities of, 149in blackberries, 75in blueberries, 76in red raspberries, 76in strawberries, 74

Vapor phase diffusion during dehydration, 317–318

Vegetablesantioxidant activity of, 189phenolic content of, 188

Viral disease outbreaks, association of with contaminated frozen berries, 236–237

Vitamin C. See also Ascorbic acidantioxidant activity of, 196postharvest loss of, 215–217

Vitamin K, 58Vitamins, 58–59

postharvest loss of, 215–220Volatile compounds, 210

W

Washing, 351prevention of contamination by, 244

Washington, red raspberry production in, 9

Water, crystallization of, 293Water activity, 315–317, 331

control of in jam and jelly processing, 370–371

sugar infusion and, 327–328Water bath pasteurizers, 355



Water source, ensuring microbial safety of, 242

Water stress, 220Water-soluble vitamins, postharvest loss of,

215–220Wee-kee, 14. See also Hardy kiwifruitWet harvesting, cranberries, 40White cranberries, 41. See also CranberriesWhite currants, 14

production systems for, 42Wine

phenolics in pomace extracts from, 393–394

processing, 124Wisconsin, cranberry production in, 13

Wolfberries, benefits to eye health of, 132Worker hygiene, 244Wounding, 220

X

Xylose, 80, 85, 114, 150

Z

Zeaxanthin, 122benefits to eye health of, 132

Zinc, in strawberries, 63Zinc lactate. See ZLZL, 303


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Berry Fruit - Value-Added Products