1. Freezing Fruits and Vegetables at Home
Note from the author:
Other educators using this slide show for non-profit purposes are welcome to customize the title slide with your own identification, as long as credit for development of the original slide set is retained in a citation as described under “Document Use” on the final slide in this show.
Author: Elizabeth L. Andress, Ph.D.
Project Director, National Center for Home Food Preservation
Associate Professor and Extension Food Safety Specialist
The University of Georgia
Department of Foods and Nutrition Extension
208 Hoke Smith Annex
Athens, GA

2. 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
NICOLE RICHARD, MS
RESEARCH ASSISTANT
DEPT OF NUTRITION AND FOOD SCIENCES
UNIVERSITY OF RHODE ISLAND
8/2010

3. 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
Greater discussion of the points made in this slide show can be found in
So Easy to Preserve, 4th ed. Bulletin Cooperative Extension Service, The University of Georgia, Athens, GA. Ordering information:
Additional information on freezing practices can be found at:
See: General Information
Blanching Vegetables
Individual food recommendations

4. 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.
Another goal in freezing for maintaining optimum texture is to minimize the size of ice crystals formed – that is, to promote the formation of the smallest ice crystals possible. Large ice crystals do more damage to food cells and cause softer, mushier textures.
Foods that don’t freeze well (and the effects of freezing on their texture) are summarized at:

5. 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.
Chemical and physical changes occur in fruit and vegetable tissue as they mature. Initially they may help the produce reach its peak quality, but then they can also contribute to its decay. Freezing will only slow enzyme activity, and for many foods, this is sufficient. In other foods, especially vegetables, enzymes should be destroyed (by heat) prior to freezing in order to prevent undesirable color, flavor and texture changes.
Examples of enzymatic changes in fruits and vegetables:
Formation of “lignin” or tough, stringy texture in some vegetables (asparagus, spinach, broccoli).
Browning of cut apples, bananas, peaches, cherries, pears.
Softening of fruits from breakdown of natural pectins, caused by pectin-degrading enzymes.
Development of potent, unpleasant odor compounds in cut garlic, leeks and onions, and overcooked broccoli, cabbage and Brussels sprouts.
Breakdown of colors to less desirable forms in bright green vegetables.
Brown to dark gray discoloration of cut white potatoes.

6. 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

7. 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.
Here is a review of how freezing can adversely the quality of foods.
One of the biggest contributors to poor texture in frozen fruits and vegetables is large ice crystals.
(The package of frozen strawberries pictured on this slide represents the appearance of large ice crystals formed outside the pieces of food. This is typical of food stored in a freezer with fluctuating temperatures, where moisture is pulled from the product and refreezes outside the cells.)
The air in a freezer is very dry. If foods are improperly packaged so they are exposed to the air in the freezer, or moisture is pulled through the packaging material from inside to outside the package, the food dries out. Freezer burn is an example of drying out of food tissue. Freezer burn often looks like a grainy, brownish or whitish spot on the surface of foods, where the tissues become dry and tough. Packaging in heavy-weight, moisture- and vapor-resistant wrap will prevent freezer burn. This dried surface area is very likely to develop off-flavors, but it will not cause illness. (Freezer burn is a quality issue, not a safety issue.)

8. 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).

9. 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

10. Packaging Moisture-vapor resistant Durable and leak-proof
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.
Foods for your freezer must have proper packaging materials to protect their flavor, color, moisture content and nutritive value from the dry climate of the freezer. The selection of containers depends on the type of food to be frozen, personal preference and types that are readily available. Do not freeze fruits and vegetables in containers with a capacity over one-half gallon. Foods in larger containers freeze too slowly to result in a satisfactory product.

11. 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.
Rigid containers made of plastic or glass are especially good for liquid packs, although they are suitable for most all packs. Straight sides on rigid containers make the frozen food much easier to get out. Rigid containers are often re-useable and make the stacking of foods in the freezer easier. Cardboard cartons for cottage cheese, ice cream and milk are not sufficiently moisture-vapor resistant to be suitable for long-term freezer storage, unless they are lined with a freezer bag or wrap.
Regular glass jars break easily at freezer temperatures. If using glass jars, choose wide-mouth dual purpose jars made for freezing and canning. These jars have been tempered to withstand extremes in temperatures. The wide-mouth allows easy removal of partially thawed foods. If standard canning jars (those with narrow mouths) are used for freezing, leave extra headspace to allow for expansion of foods during freezing. Expansion of the liquid could cause the jars to break at the neck. Some foods will need to be thawed completely before removal from the jar when the opening is more narrow than the container below it.
Covers for rigid containers should fit tightly. If they do not, reinforce the seal with freezer tape. Freezer tape is especially designed to stick at freezing temperatures.

12. Packaging Good for firm, non-juicy foods. Bags Wraps
plastic (such as polyethylene)
heavy-duty aluminum foil
laminated paper- “freezer paper”
Good for firm, non-juicy foods.
Bags and sheets of moisture-vapor resistant materials and heavy-duty aluminum foil are suitable for dry packed vegetables and fruits, meats, fish or poultry. Bags can also be used for liquid packs. Protective card board cartons may be used to protect bags and sheets against tearing and to make stacking easier (but they are hard to find in today’s marketplace).
The plastics used in freezer wraps and bags are of a different composition and/or thickness than regular plastic storage bags. Use a plastic bag or wrap recommended for freezing for the best moisture-vapor barriers.
Laminated papers made of various combinations of paper and plastics or cellophane are most suited to meats, fish, poultry and some baked food, but can also be used for dry packed fruits and vegetables. Laminated papers are also used as protective over-wraps, over foils or plastic bags.
Foils are more easily torn or punctured than plastic wraps; be sure to use freezer-strength foil if that is your choice.

13. Packaging Vacuum Sealers - Always defrost in the refrigerator
- Cut several holes in the
plastic so
environment in
the bag is not
“air-free”

14. Packing Foods Food must be cool Pack in serving size quantities.
Cool all foods and syrup before packaging. This speeds up freezing and helps retain the natural color, flavor and texture of food.
Pack foods in quantities that will be used for a single meal.
Follow directions for each individual food to determine which can be packed dry and which need added liquid. Some loose foods such as blueberries may be "tray packed" (frozen first on a tray before packaging, see slides 42 and 43).

15. 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
Pack foods tightly as you work towards the top of the container, leaving as little air as possible throughout the food in the package.
Most foods require headspace between the packed food and closure to allow for expansion of the food as it freezes. Foods that are exceptions and do not need headspace include loose packing vegetables such as asparagus and broccoli, bony pieces of meat, tray packed foods and breads.
Headspace allowances for various foods can be found at:
For liquid, pureed, or crushed fruits in containers with wide openings, allow ½-inch for pints and 1 inch for quarts. In narrow mouth containers, allow ¾ inch for pints and 1 ½ inches for quarts.
For juices in containers with wide openings, allow ½-inch for pints and 1 inch for quarts. In narrow mouth containers, allow 1 ½ inches for pints and quarts.
For fruits and vegetables dry-packed (pieces without liquid), allow ½ inch for all containers.

16. 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
When food is packaged in bags, press the air firmly from the bag. Begin at the top of the food and press air out as you move toward the unfilled top, keeping the edges pressed together in a manner to keep air from getting back in the package. If you do not have a zippered bag, leave enough bag above the food to twist a tight column about 1 ½ to 2 inches long. Fold the the top half of the twisted column over and down against the bottom half of the twisted column (called gooseneck style) and secure with a twist tie.
Seal rigid containers carefully. Use a tight lid and keep the sealing edge free from moisture or food to ensure a good closure. Any liquid or food trapped in the sealing area will expand when frozen and cause air gaps in the seal. Secure loose-fitting covers with freezer tape.

17. 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.
Select products of best quality at optimum maturity and freshness. Freezing does not improve quality.
Select varieties suitable for freezing. (Check a seed catalog or ask the grower.)
If the fruits can not be frozen immediately, refrigerate them.
Work in small quantities: enough for only a few containers at a time, to prevent loss of quality and nutrients.
Wash and drain all fruits before removing hulls (caps), cores, pits, seeds, skins or shells.
Wash small lots at a time through several changes of cold water. Lift produce out of the water so the dirt washed off will not get back on the food. Do not let the fruits soak.
When preparing fruit for freezing do not use galvanized, copper or iron equipment. The acid in the fruit could react with the metals forming harmful compounds or off-flavors.

18. 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
Some fruits such as peaches, apples, pears and apricots darken quickly when exposed to air and during freezing. They may also lose flavor when thawed. There are several ways to prevent darkening of fruit and flavor loss.
Ascorbic acid or vitamin C is preferred for being effective in preventing discoloration in most fruits. Not only does it preserve natural color and flavor of fruits, but it adds nutritive value as well.
In addition to not being as effective as ascorbic acid, lemon or other fruit juices can interfere with natural fruit flavors.
Salt and vinegar solutions are no longer recommended. The solution may help prevent browning initially, but light colored fruits can eventually become gray in appearance.

19. 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.
Photo: You will need sugar (lots more of it, though!) and water to make a covering syrup. (You may also use ascorbic acid in your syrup).
The proportion of sugar to water depends upon the sweetness of the fruit to be frozen. A 40 percent syrup is recommended for most fruits. Lighter syrups are desirable for mild-flavored fruits to prevent masking of flavors. Heavier syrup may be needed for very sour fruits.
Options for making syrups of varying concentrations can be found at
To make the syrup, dissolve sugar in lukewarm water, mixing until the solution is clear. Chill syrup before using.
Use just enough cold syrup to cover the prepared fruit after it has been placed in the container (about ½ to b cup of syrup per pint). To keep fruit under the syrup, place a small piece of crumpled parchment paper or other water resistant wrapping material on top, and press fruit down into the syrup before sealing the container.

20. Preparing Peaches in Syrup
Photos: Notice fruit pieces tend to want to float above the syrup cover. To keep fruit under the syrup, place a small piece of crumpled parchment paper or other water resistant wrapping material on top, and press fruit down into the syrup before sealing the container. This pack uses freezer paper, with the plasticized side down onto the fruit and syrup. Notice in the bottom photo, all the peach pieces are under the syrup and crumpled paper.

21. 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.
Sprinkle sugar over the fruit and mix gently until the juice is drawn out and the sugar dissolved. Soft sliced fruits such as peaches, strawberries, figs, de-seeded grapes, plums and cherries will yield sufficient syrup for covering if the fruit is layered with sugar and allowed to stand 15 minutes. Some small whole fruits may be coated with sugar and frozen.

22. Unsweetened Packs for Fruit
Dry Pack
Good for small whole fruits
such as berries that don’t need sugar.
Simply pack into containers and freeze.
Or may be frozen individually, in single layer, on a tray first.
“Tray pack” – next slide
The dry pack is good for small whole fruits such as berries, that give a good quality product without sugar. Simply pack the fruit into a container, seal and freeze.
Photo: Dry-packed fruits are simply placed in containers. ½ inch headspace is allowed.
Even fruit pieces dry-packed in this manner may “clump” together if not frozen very rapidly. Moisture left clinging to the fruit pieces will facilitate this “clumping” as the fruit pieces freeze together with external ice crystals.
A tray pack is an alternative that may make the fruit easier to remove from the container.

23. 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.
This method is also called an Individually Quick Frozen pack, or IQF. The commercially frozen fruits you buy that are unsweetened, separate pieces in the package are done by the true IQF procedure, a term that was developed for an industry practice.
Spread a single layer of prepared fruit on shallow trays and freeze. When frozen, promptly package and return to the freezer. The fruit pieces remain loose and can be poured from the container and the package re-closed. Be sure to package the fruit as soon as it is frozen, to prevent freezer burn.
Photos: Note the iciness and firmness to these pieces in the containers, after having been tray-frozen before packaging.

24. 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.
Photos: Compare the appearance between IQF fruit and fruit pieces packed with sugar syrup.

25. 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.
In addition to a dry pack, unsweetened fruit can be packed in water, unsweetened juice or pectin syrup.
Unsweetened packs generally yield a product that does not have the plump texture and good color of those packed with sugar. The fruits freeze harder and take longer to thaw. However, some fruits such as raspberries, blueberries, steamed apples, gooseberries, currants, cranberries, rhubarb and figs give a good quality product without sugar.
The pectin syrup is often used for fruits such as strawberries or peaches, that retain their texture better than if frozen in water or juice.

26. 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.
Sugar substitutes (aka “artificial sweeteners”) may be used in any of the unsweetened packs. Both saccharin and aspartame work well in frozen products or they can be added to the fruit just before serving.
Artificial sweeteners give a sweet flavor but do not furnish the beneficial effects of sugar, such as color protection and thickness of syrup.
Labels on the products give the equivalents to a standard amount of sugar. Use directions on the container to determine the amount of sweetener needed.

27. 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.
Select products of best quality at optimum maturity and freshness. Choose fresh, young, tender vegetables. Freezing does not improve quality.
Select varieties suitable for freezing.
Freeze them before they lose their freshness.
If the vegetables cannot be frozen immediately, refrigerate them.
Wash and drain all vegetables before removing skins or shells. Wash small lots at a time through several changes of cold water. Lift the produce out of the water so the dirt washed off will not get back on the food. Do not let the vegetables soak.
Work in small quantities; enough for only a few containers at a time, to prevent loss of quality and nutrients.

28. 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.
Blanching (scalding vegetables in boiling water or steam for a short time) is a must for almost all vegetables to be frozen. It stops enzyme actions which can cause loss of flavor, color and texture.
Blanching cleanses the surface of dirt and organisms, brightens the color and helps retard loss of vitamins. It also wilts or softens vegetables and makes them easier to pack.
Blanching time is crucial and varies with the vegetable and size. Underblanching stimulates the activity of enzymes and is worse than no blanching. Overblanching causes loss of flavor, color, vitamins and minerals.

29. How to Blanch Vegetables
Use specific directions.
Work in small quantities.
Blanching is not intended to cook vegetables, just heat them throughout so the heat reaches all the enzymes being targeted for destruction. Immediately after blanching, vegetables are cooled quickly to stop them from cooking.
(Note: Vegetables that are purposely cooked prior to freezing, e.g., stewed tomatoes, have the enzymes inactivated as part of the cooking process.)

30. 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.
Blanching times are intended to be at the temperature of boiling water.
Have the water in the blancher vigorously boiling before adding the prepared vegetable. Use a lid after adding vegetables, to keep the water boiling vigorously.
Small quantities are recommended to avoid the vegetables being in hot water any longer than necessary, since the goal is not to cook them. One pound of vegetables will require at least 1 gallon of boiling water. If the water loses its boil when the vegetable is added, wait for the water to boil before starting to count the blanching time. If it takes too long to come to a boil (more than a minute), use less vegetable to the amount of water. If you do not wait for the water to come back to a boil, you could under-blanch your vegetables and actually stimulate enzymes to work faster, rather than destroy them.
If you are blanching several loads in a row, remember to add water back to the blancher as it boils away.

31. 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.
Heating in steam is recommended for a few vegetables. For broccoli, pumpkin, sweet potatoes and winter squash, both steaming and boiling are satisfactory methods. Steam blanching takes about 1½ times longer than water blanching.
To steam, use a pot with a tight lid and a basket that holds the food suspended over (not touching or in) the boiling water. Put an inch or two of water in the pot and bring the water to a boil.
Put the vegetables in the basket in a single layer so that steam reaches all parts quickly. Cover the pot and keep heat high. Start counting steaming time as soon as the lid is on.
Takes 1-1/2 times longer than water blanching. Check times, however, for each food.

32. 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.
USDA currently does not have microwave blanching recommendations published.
Microwave blanching is controversial, since most microwave ovens have unevenness in cooking pattern and the goal of blanching is to be sure to destroy enzymes, not just heat and stimulate them to faster action.
Microwave ovens are most convenient for freezing/blanching small quantities of vegetables.
When directions have been published, there have been some consistencies in managing the process.
Due to the unevenness in cooking pattern, make sure vegetables being blanched are stirred or re-arranged halfway through the blanching time.
Most recommendations call for 4 cups or less of vegetable at at time.
Usually a 1-minute standing time, while covered, is recommended prior to cooling.

33. 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.
As soon as blanching by any method is complete, vegetables should be cooled quickly and thoroughly to stop the cooking process. To cool, plunge the basket of vegetables immediately into a large quantity of icy, cold water, at least 60oF or below. (Three to 4 gallons of icy water is best.)
Use cold running water or iced water. If ice is used, about one pound of ice for each pound of vegetable is needed. Cooling vegetables should take the same amount of time as blanching.
Drain vegetables thoroughly after cooling. Extra moisture can cause a loss of quality when vegetables are frozen.

34. 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.
Dry Pack—After you have blanched, cooled and drained the vegetable, package it quickly. Remove as much air as possible, but allow proper headspace and seal.
(Headspace is the same as for fruit containers)

35. 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.
Tray Pack—After you have blanched, cooled and drained the vegetable, spread in a single layer on shallow trays or pans (as was described for fruits).
Place in the freezer just long enough to freeze firm. After the first hour, check often. Long exposure will result in loss of moisture.
Package quickly, leaving no headspace, then seal. Tray packed vegetables remain loose and can be poured from the container and the package re-closed.

36. Disclaimer and Credits
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 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
Note from the author: (see slide 1 for author information)
If this slide set is used without changes, the citation should say “reprinted…”
If it is used with changes, please state “adapted” in the citation.