Transcript Chapter 30 Food Preservation by Freezing and Canning

Food Preservation by
Freezing and Canning
Chapter 30
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
2
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Freezing Process

Three stages




Microorganism activity is minimal


Product lowered to freezing
Ice crystals form
Temperature lowered to storage temperature
Will grow after thawing
Enzyme processes may continue

Blanching
Introductory Foods, 13th ed.
Bennion and Scheule
3
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
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
4
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Changes in Frozen Food

Nonenzymatic Oxidation



Desiccation



Usually associated with fat
Fat of pork particularly susceptible
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
5
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Freezing Techniques





Fruits
Vegetables
Meat, Fish, Poultry
Eggs
Prepared Foods
Introductory Foods, 13th ed.
Bennion and Scheule
6
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Other Issues

Container selection

Use and management of freezer
Introductory Foods, 13th ed.
Bennion and Scheule
7
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
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
8
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Canning History

French prize


Development of tin canister


Nicolas Appert – 1809 preserved foods
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
9
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Home Canning

Containers – Glass jars

Pack methods


Raw
Hot
Introductory Foods, 13th ed.
Bennion and Scheule
10
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
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
11
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
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
12
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Additional Issues

Heat penetration

Obtaining a partial vacuum

Obtaining an effective seal

Handling after processing
Introductory Foods, 13th ed.
Bennion and Scheule
13
© 2010 Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.