Freezing Fruits and Vegetables at Home

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Freezing Fruits and Vegetables at Home
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Adapted from Cooperative Extension Service
College of Family and Consumer Sciences
University of Georgia

• MARTHA SMITH PATNOAD, MS, CP-FS
• CE FOOD SAFETY EDUCATION SPECIALIST
• 401-874-2960
• mpatnoad_at_uri.edu
• NICOLE RICHARD, MS
• RESEARCH ASSISTANT
• 401-874-2977
• nicolerichard_at_uri.edu
• DEPT OF NUTRITION AND FOOD SCIENCES
• UNIVERSITY OF RHODE ISLAND
• 8/2010

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Advantages of Freezing

• Many foods can be frozen.
• Good natural color, flavor and nutritive value
  retained.
• Texture usually better.
• Takes less time
• Easy to do
• Foods can be frozen in any quantity

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How Freezing Affects Food

• Textural Changes
• The water in food freezes and expands.
• Ice crystals cause the cell walls of fruits and
  vegetables to rupture, making them softer when
  thawed.
• Some vegetables with very high water content do
  not freeze well celery, lettuce, some tomatoes.

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How Freezing Affects Food

• To prevent color and flavor changes, as well as
  loss of some nutrients, enzymes should be
  controlled
• Enzymes are small proteins in foods that start or
  help with reactions, such as those that cause
  browning, off-flavors, ripening, mushiness, etc
• .
• Are slowed down but not destroyed during
  freezing.

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How Freezing Affects Food

• Enzymes in Vegetables
• Are destroyed by blanching which is a quick heat
  and quick cooling
• Enzymes in Fruits
• Usually controlled the addition of sugar and
  antioxidants such as ascorbic acid ( vitamin C)
  or ascorbic acid mixtures

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How Freezing Affects Food

• Fluctuating Freezer Temperatures
• Ice in food thaws a little and then
  re-freezes
• Ice crystals get bigger each time.
• Food becomes mushy as large ice crystal growth
  damages cells
• Moisture is pulled out of the food
• Other quality losses speeded up due to higher
  temperatures.
• Moisture Loss
• Freezer burn tough and dry, but safe.

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General Freezing Guidelines

• 1. Freeze foods at 0oF or lower.
• 24 hours in advance of freezing large quantities
  of food, set freezer at -10oF or lower
• Keep work areas, containers, utensils clean
• Follow established directions.
• Freeze foods immediately after prep.
• Do not overload freezer
• Freeze amount that will freeze in 24 hours (2 to
  3 pounds of food per cubic foot).

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Freezing Guidelines, cont.

• Pack already frozen foods together to prevent
  thawing
• Place unfrozen foods in contact with surfaces and
  in coldest parts of freezer
• Leave space around packages so cold air can
  circulate.
• Arrange frozen foods so that the foods frozen
  longer can be used first
• Check thermometer
• Time of storage- 1 year at 0 F

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Packaging

• Moisture-vapor resistant
• Prevents transfer of moisture and air in and out
  of the package
• Durable and leak-proof
• Does not become brittle and crack at low
  temperatures
• Resistant to oil, grease or water
• Protects foods from absorption of off flavors
  or odors.
• Easy to seal and label.

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Packaging

• Rigid Containers
• Plastic freezer containers.
• Wide-mouth canning/freezing jars.
• Good for liquids or soft, juicy, or liquid-packed
  foods.
• May be reusable.
• Hold their shape and can be stored upright.

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Packaging

• Bags
• Wraps
• plastic (such as polyethylene)
• heavy-duty aluminum foil
• laminated paper- freezer paper
• Good for firm, non-juicy foods.

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Packaging

• Vacuum Sealers
• - Always defrost in the refrigerator
• - Cut several holes in the
• plastic so
• environment in
• the bag is not
• air-free

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Packing Foods

• Food must be cool
• Pack in serving size quantities.

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Packing Foods to be Frozen

• Pack foods tightly
• Avoid trapped air (oxygen)
• Allow for headspace as food may expand except
• uneven vegetables like
• broccoli and asparagus

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Packing Foods- Sealing

• Press all air from bagged foods.
• Except for headspace.

• Use tight lid on rigid containers
• Keep sealing edges clean and dry. Use freezer
  tape over seams of looser-fitting covers.
• Trapped food or liquids in sealing area will
  freeze, expand, and loosen seal.
• Always label with date and contents

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Freezing Fruits

• Frozen in many forms
• Whole, sliced, crushed, juiced.
• Best quality
• Optimum maturity and freshness.
• Immature or overripe both produce lower quality
  when frozen.
• Wash and work with small amounts at a time to
  preserve best quality.

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Preventing Fruit Darkening

• Ascorbic acid ( Vitamin C)
• Heating the fruit
• Ascorbic Acid Mixtures
• -Fruit Fresh and others
• - Have some other added ingredients.
• -Follow package directions to obtain correct
  strength
• Do not work as well
• Citric acid
• Lemon juice
• Sugar syrup
• Salt/vinegar solution

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Sweetened Packs for Fruit

• Sugar Syrup Pack
• Better texture.
• Not needed for safety.
• Fruits should be covered with syrup.
• Place crumpled water-resistant paper in top of
  container.

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Preparing Peaches in Syrup
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Sweetened Packs for Fruit

• Sugar Pack
• Sliced soft fruits (strawberries, peaches, etc.)
  make their own syrup when mixed with the right
  proportion of sugar.
• Layer fruit and sugar in bowl or pan.
• Allow mixture to stand 15 minutes to make juice
  or syrup before packaging.

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Unsweetened Packs for Fruit

• Dry Pack
• Good for small whole fruits
• such as berries that dont need sugar.
• Simply pack into containers and freeze.
• Or may be frozen individually, in single layer,
  on a tray first.
• Tray pack next slide

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Dry Tray Pack for Fruit

• Fruit pieces may be frozen individually, in
  single layer, on a tray first.
• Freeze until firm then package in rigid container
  or bag.
• Will pour out of container easily when frozen.

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Dry Tray Pack for Fruit

• Can remove only the amount needed at one time.
• Fruit pieces retain shapes.
• Fruit pieces do not clump as when packed
  directly into containers or with sugar syrup.

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Unsweetened Packs for Fruit

• Pectin Syrup
• Good for strawberries and peaches.
• Mix 1 package powdered pectin and 1 cup water.
  Bring to boil, boil 1 minute. Remove from heat,
  cool and add 1-3/4 cups more water.
• Water or Unsweetened Juice Packs
• Texture will be mushier.
• Color poorer.
• Freezes harder, takes longer to thaw.

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Sugar Substitutes

• May be used in the pectin syrup, juice or water
  packs.
• Or could be added just before serving.
• These do not help with color retention or
  texture, like sugar does.
• Use amounts on product labels or to taste.

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Freezing Vegetables

• Select young, tender, high-quality vegetables.
• Sort for size and ripeness.
• Wash and drain before removing skins or shells.
• Wash small lots at a time, lifting out of water.
  DO NOT SOAK.
• Work in small quantities, preparing as directed.

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Preventing Flavor and Color Changes in Vegetables

• Blanching
• Primary method to destroy enzymes for vegetables.
• Will also soften hard veggies to make packaging
  easier.
• Will also remove some microorganisms.
• Under-blanching can be harmful it will stimulate
  enzymes and not destroy them. Check required
  blanching times for each food.

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How to Blanch Vegetables

• Use specific directions.
• Work in small quantities.

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How to Blanch Vegetables

• In Boiling Water
• Use blancher with lid or a
• kettle with basket and lid.
• Have 1 gallon water per 1 lb. of vegetables.
• Place vegetables in blanching basket.
• Lower vegetable into vigorously boiling water.
  Put lid on. Water should hardly stop boiling or
  return to a boil within a minute.
• If water keeps boiling, begin timing immediately.
  Otherwise, wait for water to come back to a boil.

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How to Blanch Vegetables

• Steam Blanching
• Use kettle with tight lid and basket.
• 1 to 2 of boiling water in bottom
• of pan.
• Vegetable should be in a single layer in basket.
• Start timing when covered.

• Takes 1-1/2 times longer than water blanching.
  Check times, however, for each food.

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How to Blanch Vegetables

• Microwave Blanching
• Not widely recommended at this time.
• May not be effective enzymes not inactivated
  completely by uneven heating.
• Usually does not save time.
• Have to do very small quantities.
• If you have directions from a source you trust,
  try small quantities at first and see if you like
  the quality after a period of frozen storage.
• This is not a safety issue, as long as frozen
  food is always stored frozen, but improper
  blanching will affect quality.

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How to Blanch Vegetables

• After blanching in water or steam, cool
  immediately in cold water.
• Change water frequently or use running water or
  iced water (1 lb. ice per 1 lb. vegetable).
• Cooling time should be the same as the blanching
  time.
• Drain thoroughly.

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Types of Pack for Vegetables

• Dry Pack
• Pack after the vegetables are blanched, cooled,
  and drained.
• Pack quickly, pushing air out of package as you
  work towards top.

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Types of Pack for Vegetables

• Tray Pack
• After draining, spread pieces in a single layer
  on a shallow pan.
• Freeze firm.
• After first hour, check often.
• Package quickly, pushing air out as you work.

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Disclaimer and Credits

• Disclaimer
• Trade and brand names are used only for
  information. The Cooperative Extension Service,
  University of Georgia College of Agricultural
  Environmental Sciences and College of Family
  Consumer Sciences, and the U.S. Department of
  Agriculture do not guarantee nor warrant
  published standards on any product mentioned
  neither does the use of a trade or brand name
  imply approval of any product to the exclusion of
  others which may also be suitable.
• Document Use
• Permission is granted to reproduce these
  materials in whole or in part for educational
  purposes only (not for profit beyond the cost of
  reproduction) provided the author and the
  University of Georgia receive acknowledgment and
  this notice is included
• Reprinted (or Adapted) with permission of the
  University of Georgia. Andress, E.L. 2003.
  Freezing fruits and vegetables at home (slides).
  Athens, GA The University of Georgia,
  Cooperative Extension Service.
• This material is based upon work supported by the
  Cooperative State Research, Education, and
  Extension Service, U.S. Department of
  Agriculture, under Agreement No. 00-51110-9762.