Food Preservation by Freezing and Canning

Chapter 30

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.2

Freezing

Clarence Birdseye began frozen food industry in 1920s

Research and Developments “Antifreeze” proteins - control size of ice crystals Air impingement – fast cooling Pressure shift – small crystals Time-temperature indicators – monitor temperatures

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.3

Freezing Process

Three stages Product lowered to freezing Ice crystals form Temperature lowered to storage temperature

Microorganism activity is minimal Will grow after thawing

Enzyme processes may continue Blanching

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.4

Changes in Frozen Foods

Formation of crystals Fruits and vegetables cells may be damaged Rapid freezing favors small ice crystals

Enzyme Action Blanching Sugar or sugar syrups

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.5

Changes in Frozen Food

Nonenzymatic Oxidation Usually associated with fat Fat of pork particularly susceptible

Desiccation Moisture loss by sublimation Freezer burn

Activity of Microorganisms Inactive or minimally active at low temperatures Growth and activity resume after thawing

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.6

Freezing Techniques

Fruits Vegetables Meat, Fish, Poultry Eggs Prepared Foods

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.7

Other Issues

Container selection

Use and management of freezer

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.8

Canning

Application of heat to destroy essentially all microorganisms Vegetative Cells and spores

Sealing product in sterilized containers

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.9

Canning History

French prize Nicolas Appert – 1809 preserved foods

Development of tin canister Early 1800’s canned foods for British Navy

Commercial canning Batch and continuous retorts Aseptic canning Retort pouch

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.10

Home Canning

Containers – Glass jars

Pack methods Raw Hot

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.11

Home Canning (Processing)

Boiling water bath (212°F / 100°C) Must be high pH or ACIDIC foods Tomatoes may or may not have adequate acid levels Follow recommended time and temperatures

Pressure canning (240°F / 116°C) LOW ACID foods must be processed with pressure

pH higher than 4.6 Use pressure canner with accurate gauge Adjustments necessary at high altitudes Use recommended pressure and time Allow pressure cooker to cool and depressurize

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.12

Containers

Commercial canning Tin-plated steel Aluminum Glass Retort flexible packages

Home canning Glass jars with self-sealing lids No larger than quart size is recommended

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.13

Additional Issues

Heat penetration

Obtaining a partial vacuum

Obtaining an effective seal

Handling after processing