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Freezing Food. History. The frozen food industry was born in the 1920’s Clarence Birdseye produced the first frozen fish. History. The industry continued to grow and develop with the growth of such technology as fast-freezing equipment, home freezers, and the microwave oven
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History • The frozen food industry was born in the 1920’s • Clarence Birdseye produced the first frozen fish
History • The industry continued to grow and develop with the growth of such technology as fast-freezing equipment, home freezers, and the microwave oven • The 1950’s brought on the TV dinner revolution
The Science of Freezing • It preserves food by slowing the action of enzymes rather than destroying them
The Science of Freezing • Foods that are free of microorganisms when frozen will remain so, since most microorganisms can’t grow at such a low temperature
Freezer Burn • Caused by the loss of moisture from food when the food is exposed to air • Culprit: Loose packaging, fluctuation in freezer temperature
Freezer Burn • If not packaged properly, even foods that do freeze well can experience a damaging effect • Foods that are freezer burnt often have a brown or grayish color, look very dry, and have a fuzzy gray or white spots that look like icy mold
Commercial Freezing • Rapid Freezing Process – Limited changes in color, texture, size and flavor • Also, helps foods resist freezer burn • Ice crystals are smaller causing less damage to food cells
Commercial Freezing • Freezing in air is the oldest and still the most common method of freezing food, and also the one used in home freezing • Indirect-contact freezing is food that is placed on belts or trays. A refrigerant circulates through the wall beside the food and it chills quickly and freezes
Commercial FreezingCont… • Immersion freezing food is submerged directly in non-toxic refrigerant to cause quick freezing • Most packaging is opaque because many foods lose flavor when exposed to light
Home Freezing • Storage containers and wraps used for frozen foods at home must be moisture proof and airtight to maintain quality
Home Freezing • Even if it is properly maintained it has a 6-12 month period before it starts to deteriorate
Home Freezing • Foods with high water content, including grapes, pears, salad greens, lose shape and texture when frozen • Be sure to label and date all packages!!
Freeze-drying • Is a commercial process that combines freezing and drying to preserve foods. • First food is frozen; then its treated to remove the solvent from dispersed or dissolved solids. • In most food, this means removing the water. • Technical name: lyophilisation.
Sublimation • During freeze-drying, water in the form of ice is removed through sublimation – occurs on the surface and continues inward. • Wet clothes on the line during winter example. • By the time the ice at the very center has sublimed, up to 99% of the food’s moisture has been removed. • The result is dried food.
Sublimation • Flash frozen or frozen very quickly – a special, low-pressure chamber. It is then held at or below freezing temperature. • The low temperature keeps the water frozen, and the low pressure speeds the rate at which ice crystals in the food escapes as water vapor.
Using Freeze Dried Foods • Foods could be stored for months even years • Must be protected in airtight packaging • Examples are fruit in cereal and chicken in instant soup • Makes foods extremely light – should be reconstituted.
Packaging Food • Suitable containers • Safety – needs to be non-toxic and provide a sanitary, protected environment • Food quality – must provide protection from light, odors • Convenience – open easily, resealable, and able to pour easily are a + • Expense – lower packaging means lower cost for manufacturers and the result is a lower cost to consumers! • Environmentally safe – recyclable containers! • Marketing appeal – attractive to the consumer!
Packaging Food • Modified-atmosphere packaging • Called MAP – This process creates a specific gaseous environment for a food product to lengthen shelf life. • Used mainly for ready-to-eat products with extended shelf lives. • Bags of lettuce, baby spinach, and baby carrots use this technology in stores!
Packaging Food • Aseptic packaging • Used for beverages and liquids that have been aseptically treated – extremely high temperatures and contain several layers of material. • Containers are not recyclable. • Example: Drink boxes!
Packaging Food • Edible films/wraps • Additional film added to apples - Wax • Trends in packaging • Edible films • “Smart” packaging that tells the consumer a number of things – if the temperature has ever risen enough above the proper temperature the the contents of the package may be unsafe to consume • “Intelligent” packaging that tells the consumer whether or not the contents are spoiled and may not be safe to eat. Ex. A dot that may change colors
Irradiation • One third of the world’s food supply is still degraded or destroyed by pests, bacteria, and the resulting spoilage. • Irradiation – food is exposed to a controlled amount of radiation (transfer of energy in the form of waves) for a specific time to destroy organisms that would cause spoilage.
Irradiation • Radura Symbol – Page 462 • The FDA (Food and Drug Administration) regulates irradiation as an additive. • Delaney Clause – states that no substance shown to cause cancer in humans or animals may be added to food in any amount. • The FDA approves food for irradiation on a case-by-case basis.
