Freezing Food

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Freezing Food
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History

• The frozen food industry was born in the 1920s
• Clarence Birdseye produced the first frozen fish

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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 1950s brought on the TV dinner revolution

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The Science of Freezing

• It preserves food by slowing the action of
  enzymes rather than destroying them

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The Science of Freezing

• Foods that are free of microorganisms when frozen
  will remain so, since most microorganisms cant
  grow at such a low temperature

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Freezer Burn

• Caused by the loss of moisture from food when the
  food is exposed to air
• Culprit Loose packaging, fluctuation in freezer
  temperature

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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

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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

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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

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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

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Home Freezing

• Storage containers and wraps used for frozen
  foods at home must be moisture proof and airtight
  to maintain quality

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Home Freezing

• Even if it is properly maintained it has a 6-12
  month period before it starts to deteriorate

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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!!

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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.

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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 foods moisture has
  been removed.
• The result is dried food.

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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.

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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.

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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!

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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!

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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!

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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

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Irradiation

• One third of the worlds 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.

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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.

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Radura Symbol