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Freezing%20Fruits%20and%20Vegetables%20at%20Home

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Ground Beef. 1 pound. 30. Freezing Guidelines. 1. Freeze foods at 0oF or lower. ... When used in recipes, allow for added sugar and more juice. 59. Thawing ... – PowerPoint PPT presentation

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Title: Freezing%20Fruits%20and%20Vegetables%20at%20Home


1
Freezing Fruits and Vegetables at Home
  • Cooperative Extension Service
  • The University of Georgia
  • College of Family and Consumer Sciences

2
Advantages of Freezing
  • Many foods can be frozen.
  • Good natural color, flavor and nutritive value
    can be retained.
  • Texture usually better than for other methods of
    food preservation.
  • But this is personal preference.
  • Foods can be frozen in less time than they can be
    dried or canned.

3
Advantages of Freezing
  • Simple procedures.
  • Adds convenience to food preparation.
  • Proportions can be adapted to needs unlike other
    methods.
  • Kitchen remains somewhat cool and comfortable.

4
Disadvantages ofFreezing Foods
  • Texture of some foods is undesirable because of
    changes due to the freezing process.
  • Initial investment and cost of maintaining a
    freezer is high.
  • Storage space is limited by how much the freezer
    will hold.

5
How Freezing Affects Food
  • Enzymes in Vegetables and Fruits
  • To prevent color and flavor changes, as well as
    loss of some nutrients, enzymes should be
    controlled.
  • Are slowed down but not destroyed during
    freezing.
  • (Enzymes are small proteins in foods that start
    or help with reactions, such as those that cause
    browning, off-flavors, mushiness, etc.)

6
How Freezing Affects Food
  • Enzymes in Vegetables
  • Are destroyed by heat, called blanching, before
    packaging and freezing.
  • Enzymes in Fruits
  • Usually controlled by ascorbic acid (also called
    vitamin C) or some other additives.
  • Fruits are usually not blanched, but can be.
  • People like them raw and uncooked.

7
How Freezing Affects Food
  • Rancidity
  • Another natural change that causes off-flavors,
    particularly in fatty foods.
  • Not a common problem in fruits veggies.
  • Will continue to happen at freezer temperatures,
    but slower than at warmer temps.
  • Best control is to keep as much air out of the
    package as possible.

8
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.

9
How Freezing Affects Food
  • Rate of Freezing is Very Important
  • Freeze Foods Quickly!

10
Best Advice for Freezing
  • Freeze foods quickly.
  • Set freezer temperature at -10o F at least 24
    hours ahead of freezing large quantities of fresh
    food.
  • Spread packages out around the freezer, until
    frozen, then stack.
  • Hold at 0oF for best quality.

11
Best Advice for Freezing
  • What happens when the freezer is above 0oF ?

12
Best Advice for Freezing
  • What happens when the freezer is above 0oF ?
  • Shelf life (storage time) for best quality is
    shorter.

13
Vegetable Storage
  • For same final quality
  • Length of Storage
  • 1 year
  • 6 months
  • 3 months
  • 6 weeks
  • 3 weeks
  • 10 days
  • 5 days
  • Temperature
  • 0o F.
  • 5o F.
  • 10o F.
  • 15o F.
  • 20o F.
  • 25o F.
  • 30o F.

14
How Freezing Affects Food
  • Fluctuating Freezer Temperatures
  • Ice in food thaws a little and then
    re-freezes.
  • Ice crystals get bigger each time.
  • Mushiness because large ice crystal growth
    damages cells more and more.
  • Moisture pulled from product.
  • Other quality losses speeded up due to higher
    temperatures.
  • Moisture Loss
  • Freezer burn tough and dry, but safe.

15
Freezer Selection
  • Consider
  • Size
  • Shape
  • Efficiency
  • Defrosting features
  • Available floor area
  • Amount of freezer space needed

16
Freezer Selection
  • What size?
  • General Rule - Allow 6 cubic feet of freezer
    space per person in family.
  • (3 cubic feet per person may be adequate if other
    methods of food preservation are used).
  • Standard Freezer Capacity
  • 35 pounds of frozen food per cubic foot of usable
    space.

17
Types of Freezers
  • Upright
  • 6 to 22 cubic feet
  • Convenient
  • Uses small floor space
  • Easy to load and unload

18
Types of Freezers
  • Chest
  • 6 to 32 cubic feet
  • Takes more floor space
  • More economical to buy and to operate than
    upright
  • Loses less cold air
  • when opened

19
Types of Freezers
  • Refrigerator - Freezer Combination
  • 2 to 6 cubic feet of freezer space.
  • Freezer may be above, below or beside
    refrigerated area.
  • Be sure temperature in freezer can be maintained
    at
  • 0 degrees F. or less.

20
Types of Freezers
  • Other features to consider
  • Self defrosting or manual defrost.
  • Receptacle clips
  • prevent accidental disconnecting.
  • Door locks.
  • Drains for defrosting.

21
Location and Placementof Freezer
  • Place in convenient, cool, dry, well-ventilated
    area.
  • Do not place by stove, range, water heater or in
    the sun.
  • Do not push flush against wall. Leave space for
    air circulation and cleaning.
  • Be sure freezer is level.

22
General Freezing Instructions
  • Selection of Food
  • Freezing does not improve quality.
  • Choose highest quality available.
  • Freeze promptly.
  • Remember some foods dont freeze well.
  • Preparation
  • Work under sanitary conditions.
  • Follow recommended procedures.

23
Packaging MaterialsGood Qualities
  • 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.

24
Types of Packaging Materials
  • 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.

25
Types of Packaging Materials
  • Non-Rigid Containers
  • Bags
  • Wrappings plastic (such as polyethylene),
    heavy-duty aluminum foil, laminated paper
  • Good for firm, non-juicy foods.

26
Packing Foods to be Frozen
  • Food must be cool before freezing.
  • Ice water bath after blanching.
  • Pack in serving size quantities.
  • Usually up to 1 quart.
  • Especially when whole package must be thawed to
    get out what is needed.

27
Packing Foods to be Frozen
  • Pack foods tightly
  • Avoid trapped air (oxygen).
  • Not to waste space.
  • However, most foods need headspace or room for
    some expansion at the top, except
  • uneven vegetables like
  • broccoli and asparagus,
  • bony pieces of meat,
  • tray-packed foods,
  • and breads.

28
Packing Foods to be Frozen
  • Press all air from bagged foods.
  • Except for headspace.
  • Seal non-zippered bags by twisting the loose top,
    and then folding the top of it down over itself
    (gooseneck). Secure with twist-tie, rubber band
    or string.
  • 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.

29
Labels
9/15/02 Ground Beef 1 pound
  • Name of product
  • Added ingredients
  • Form of food - halves, whole, ground, etc.
  • Packaging date
  • Number of servings or amount

30
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.
  • 2. Freeze foods immediately after prep.
  • Do not overload freezer with unfrozen food.
  • Freeze amount that will freeze in 24 hours (2 to
    3 pounds of food per cubic foot).
  • 4. Pack already frozen foods together so they do
    not thaw.

31
Freezing Guidelines, cont.
  • 5. Place unfrozen foods in contact with
    surfaces and in coldest parts of freezer.
  • 6. Leave space around packages so cold air can
    circulate.
  • 7. When packages are frozen, organize freezer
    into types of food.
  • 8. Arrange frozen foods so that the foods
    frozen longer can be used first.
  • 9. Keep a frozen foods inventory up to date.
  • 10. Check thermometer periodically.

32
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.

33
Preventing Fruit DarkeningDuring
Preparation(Peeling, slicing, etc.)
  • 1 tsp (3000 mg) ascorbic acid to one gallon of
    cool water
  • Commercial ascorbic acid mixture
  • Heating the fruit
  • The following do not work as well
  • Citric acid solution
  • Lemon juice
  • Sugar syrup
  • Salt/vinegar solution

34
Preventing Discoloration During Freezing
  • Ascorbic Acid
  • Most economical
  • Powdered or tablet form
  • 1/2 t. powdered ascorbic acid 1500 mg
  • For tablets, use number needed for desired
    milligrams
  • (for example, 3 x 500 mg tablets 1500 mg)
  • Tablets must be crushed well

35
Preventing Discoloration During Freezing
  • Ascorbic Acid
  • Use amount specified for each fruit.
  • In syrup or liquid packs - add powdered ascorbic
    acid to the covering liquid.
  • Usually ½ tsp (1500 mg) per quart of syrup.

36
Preventing Discoloration During Freezing
  • Ascorbic Acid (cont)
  • In sugar or dry packs, dissolve the powdered
    ascorbic acid in 3 T. in cold water and sprinkle
    over fruit.
  • In sugar packs, before adding sugar.
  • Usually ¼ to ½ tsp (750 to1500 mg) per 3 T. water
    for each quart of fruit.
  • For crushed fruit, purees or juices, mix the
    powdered ascorbic acid with the prepared fruit.
  • Usually about ¼ tsp (750 mg) or less per qt. of
    fruit.

37
Preventing Discoloration During Freezing
  • Ascorbic Acid Mixtures
  • Fruit Fresh and others.
  • These have some other added ingredients.
  • Follow package directions to obtain correct
    strength of ascorbic acid.

38
Preventing Discoloration During Freezing
  • Citric Acid or Lemon Juice
  • Not as effective as ascorbic acid.
  • May mask flavors of fruits.
  • Steaming
  • Best for fruits that will be cooked before use.
  • Follow directions in freezing publications for
    times.

39
Sweetened Packs for Fruit
  • Syrup Pack
  • Better texture.
  • Not needed for safety.
  • Fruits should be covered with syrup.
  • Place crumpled water-resistant paper in top of
    container.

40
Preparing Peaches in Syrup
41
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.

42
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

43
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.

44
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.

45
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.

46
Packs for Purees or Juices
  • Pack as is, with or without sugar.
  • Add ascorbic acid if light-colored.

47
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.

48
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.

49
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.

50
How to Blanch Vegetables
  • Use specific directions.
  • Work in small quantities.

51
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.

52
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.

53
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.

54
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.

55
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.

56
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.

57
Thawing Foods for Serving
  • Fruits
  • Best if served with ice crystals.
  • Thaw
  • In refrigerator - 6 to 8 hours per pound of fruit
    in syrup.
  • At room temperature - 1 to 2 hours per pound.
  • At room temperature in cool water - ½ to 1 hour
    per pound.
  • In microwave oven - follow manufacturers
    instructions.

58
Thawing Foods for Serving
  • Dry sugar packs thaw faster than syrup packs.
  • Unsweetened packs thaw the slowest.
  • When used in recipes, allow for added sugar and
    more juice.

59
Thawing Foods for Serving
  • Vegetables
  • Cook without thawing.
  • Corn-on-the-cob should be partially thawed so cob
    will be hot.
  • Leafy greens cook more evenly if partially thawed.

60
Oh No!
  • Youve done all this work
  • and
  • the freezer stops running!

61
Freezer Emergencies
  • If know power will be off, set freezer controls
    on -10oF to -20oF immediately.
  • Do NOT open the door.
  • Foods stay frozen longer if freezer is full,
    well-insulated and in cool area.
  • Full freezer - keeps 2 to 4 days.
  • Half-full freezer - 24 hours.

62
Freezer Emergencies
  • If power interruption will be longer than 1 to 2
    days
  • Use dry ice
  • 50 lbs. - keeps full 20 cubic foot freezer below
    freezing for 3 to 4 days.
  • 50 lbs. - keeps half-full freezer for 2 to 3 days.

63
Freezer Emergencies
  • Place dry ice on boards or heavy cardboard on top
    of food.
  • Do not touch dry ice to skin.
  • Do not open freezer.
  • Room should be ventilated.

64
Refreezing Thawed Foods
  • Texture will not be as good.
  • General Rule
  • Refreeze if freezer temperature is still 40oF or
    below OR if ice crystals are still present in the
    food.

65
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.
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