Food Preservation by Freezing and Canning Chapter 30

Introductory Foods, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ All Rights Reserved. 6 Freezing Techniques Fruits Vegetables Meat, Fish, Poultry Eggs Prepared Foods

Introductory Foods, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ All Rights Reserved. 7 Other Issues Container selection Use and management of freezer

Introductory Foods, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ All Rights Reserved. 8 Canning Application of heat to destroy essentially all microorganisms Vegetative Cells and spores Sealing product in sterilized containers

Introductory Foods, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ All Rights Reserved. 10 Home Canning Containers – Glass jars Pack methods Raw Hot

Introductory Foods, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ 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, 13 th ed. Bennion and Scheule © 2010 Pearson Higher Education, Upper Saddle River, NJ All Rights Reserved. 13 Additional Issues Heat penetration Obtaining a partial vacuum Obtaining an effective seal Handling after processing