Etiket Arşivleri: Food Freezing
STORAGE OF FROZEN FOODS
The quality of a frozen-food is influenced by storage conditions. The changes in quality decrease as temperature is decreased, maintaining low storage temperatures increases the cost of frozen-food storage. Higher temperatures in frozen-food storage must be avoided due to the sensitivity of the frozen-food to temperature. Experience has established that a frozen-food storage temperature of -18℃ is accepted as a safe storage temperature for extended shelf life of a frozen food.
Fluctuation of Storage temp. on Product Quality
An increase in the product temperature results in conversion of ice to liquid state, with the possibility of re-crystallization when the temperature decreases. Small ice crystals will tend to melt as the temperature rises and change back to ice when the temperature is lowered. The re-crystallization results in an increase in ice crystal size and the impacts on quality.
Understanding factors related to freezing should minimize loss in food quality
The frozen food industry was born in the 1920’s
Clarence Birdseye produced the first frozen fish
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
Foods that are free of microorganisms when frozen will remain so, since most microorganisms can’t grow at such a low temperature
Caused by the loss of moisture from food when the food is exposed to air
Culprit: Loose packaging, fluctuation in freezer temperature
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
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
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
Storage containers and wraps used for frozen foods at home must be moisture proof and airtight to maintain quality
Even if it is properly maintained it has a 6-12 month period before it starts to deteriorate
Foods with high water content, including grapes, pears, salad greens, lose shape and texture when frozen
Be sure to label and date all packages!!
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.
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.
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.
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!
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!
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!
Additional film added to apples – Wax
Trends in packaging
“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
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.
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.