How LONG Does Food Last?

Michelle LloydDepartment of Nutrition, Dietetics and Food Science

Brigham Young University

15 June 2009

General Principles

Is it safe?

Is it nutritious?

Is it edible?•appearance•flavor•texture Sensory Nutritional

Toxicological

What defines shelf-life?

Vitamin Loss

SOURCE: Institute of Food Technologists

Vitamin Stability

Nutrient Neutral Acid AlkalineAir or oxygen

Light HeatMaximum cooking

loss

Vitamin A S U S U U U 40

Vitamin C (Ascorbic acid) U S U U U U 100

Vitamin B12 S S S U U S 10

Vitamin D S S U U U U 40

Folate U U U U U U 100

Niacin S S S S S S 75

Vitamin B6 S S S S U U 40

Riboflavin S S U S U U 75

Thiamin U S U U S U 80

Vitamin E (Tocopherols) S S S U U U 55

Source: Fennema’s Food Chemistry, 4th Edition, p 442; Adapted from Harris, RS (1971). General discussion on the stability of nutrients, in Nutritional Evaluation of Food Processing

Caution: These conclusions are oversimplifications and may not accurately represent stability under all circumstances.

What affects shelf-life of food?

Composition Water Fat Protein Carbohydrate Other components

Storage Conditions

HumidityAirLightTemperature

SOURCE: Oscar A. Pike, “Storing Fats and Oils,” Ensign, June 1999, 71

To preserve your food storage, keep it away from…

Thiamin -71% Riboflavin-21% Vitamin A -70% Lysine -80%

FreshStored ~26 yrs

From BYU Master’s Research of Michelle Lloyd, 2003

Nutrient Loss

Effect of Humidity

~3% moisture >5% moisture

Effect of Air (Oxygen)Oxygen absorber

packets can extend shelf-

life

Oxygen reacts with food Vitamin loss Off-colors Off-flavors Allows bugs to survive

Effect of Light

Speeds up reactions Vitamin loss Off-colors Off-flavors

11

Effect of Light on Hexanal in Whole Milk Powder

Effects of Temperature

From BYU Master’s Thesis of Amy Norseth, 1986

Figure 173 – Dehydrated nitrogen-packed tomato samples after 30 months storage at 40°F, 70°F, and 100°F.

Bread made from ~20 year old wheat

Hot storage Ideal storage

Effects of Temperature

Wet-Canned Foods

Source: “Progress in the Tin Plate Industry,” Food Technology, Vol. 5, #10, 1951 and Food Company Information

Approximate Shelf-life

Canned Food

8+ years corn, hominy, peas, lima beans

4+ years pumpkin and squash, sweet potatoes, tomatoes, beets, brussel sprouts, cabbage, cauliflower

3+ years asparagus, stringless beans, carrots, spinach, grapefruit

3 years apples, applesauce, apricots, fruit salad, peaches, pears, pineapple

2+ years canned meats

1+ years plums, rhubarb, blackberries, blueberries, cherries, cranberry sauce, grapes, pickles, sauerkraut, canned milk (evaporated, sweetened condensed)

Corroded Cans

BYU Research on

Long-term Storage

Collecting Samples

LDS Church News, 29 Dec 2001, 10

Collecting Samples

Nonfat Dry Milk Oatmeal Instant Potatoes Rice Dried Apples All-Purpose Flour Baking Powder Powdered Eggs Macaroni Pinto Beans Wheat Cornmeal Margarine Powder Split Peas Dehydrated Carrots

Foods Tested at BYU (from residential locations)

Dehydrated potatoes stored up to 30 yrs

Dehydrated apple slices stored up to 30 yrs

From BYU Food Storage Research, 2003

Is it Edible?

Is it Edible?

Mark whether or not you would drink each sample in an emergency situation

SOURCE: Lloyd MA, Zou J, Ogden LV, Pike OA. 2004. Sensory and Nutritional Quality of Nonfat Dry Milk in Long-term Residential Storage. J Food Sci 69(8):S326-31.

SOURCE: Lloyd MA, Zou J, Ogden LV, Pike OA. 2004. Sensory and Nutritional Quality of Nonfat Dry Milk in Long-term Residential Storage. J Food Sci 69(8):S326-31.

Is it Nutritious?

In general, the vitamins we have measured in properly stored foods are fairly stable over time.

•Thiamin

•Riboflavin

•Vitamin C

•Vitamin E

Is it Nutritious?

Vitamin C stores well in dry form

From BYU Food Storage Research, 2004

Is it Safe?

Conclusions“The results of this study suggest that rice held in accelerated andlong-term storage does not increase in mutagenic compounds.”

Ames test for mutagenicity Tested rice stored long term

Pahulu HF et al. 2007. Change in mutagenicity in white rice after accelerated and long-term storage . J Food Sci. 72 (2): C126-C131

"Life Sustaining" Shelf-LifeFood New "Life Sustaining" Shelf-

Life Estimates (In Years)

Wheat

30+White rice

Cornmeal

Pinto beans

30 Rolled oats

Pasta

Potato flakes

Apple slices

Non-fat powdered milk

20Dehydrated carrots

http://providentliving.org/content/display/0,11666,7798-1-4224-1,00.html

Shelf-life summary

No known limit:No known limit: Granulated Sugar, Salt, Baking Soda, Baking Powder

30+ years:30+ years: Wheat, White Rice

15-30 years:15-30 years: Powdered Milk, Oats, Instant Potatoes, Dried Apples, Macaroni

Pasta, Pinto Beans

Several years:Several years: Wet Canned Foods, Yeast

1-2 years: 1-2 years: Cooking Oil, Flour

Weeks: Weeks: Fresh produce