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Freezing Tips and Techniques
Preparing double or even triple recipes and freezing portions for later
means you don’t have to cook every night to have a delicious and nutritious
meal on the table.
Freezing food can be a
convenient way to store excess food or meals that you can prepare at a later
date; however, it is important to store each food type in a certain manner to
guarantee its freshness and quality. There are also steps you can take to
prevent your food from experiencing freezer burn and ensuring it retains its
texture. Take the guesswork out of freezing food with our guide that will have
you saving time, money and effort in the kitchen.
What Food Can You
Freeze?
You can freeze almost
any food. Some exceptions are canned
food or eggs in shells. However, once the food (such as a ham) is out of
the can, you may freeze it.
Being able to freeze
food and being pleased with the quality after defrosting are two different
things. Some foods simply don't freeze well. Examples are mayonnaise, cream
sauce and lettuce. Raw meat and poultry maintain their quality longer than
their cooked counterparts because moisture is lost during cooking.
When
freezing food, make
sure you leave plenty of clear space
around each container or package you are freezing to allow the air to flow
around the unfrozen food and freeze the food quickly and evenly. After the
packages are frozen, stack them more efficiently. Foods frozen in smaller quantities will freeze faster
than foods frozen in larger quantities, helping to prevent a buildup of large
ice crystals.
Use
shallow containers
with a wide surface area relative to depth. This will enable food to freeze
quickly all the way through. If using plastic freezer bags for meats,
vegetables, sauces, or soups, seal them well, then place them flat on a chilled
baking sheet until frozen solid. Again, a wide surface area will aid in the
formation of tiny ice crystals and will also make for faster thawing. It is
important to cool food completely to room temperature before freezing. Placing hot
foods in the freezer will raise its temperature, slowing down the freezing time
and possibly thawing other foods, and the centers of the foods may not freeze
quickly enough to prevent spoilage.
To make sure that foods
such as uncooked meatballs, ground meat patties, dumplings, ravioli, cookies,
profiteroles, meringues, and individual cakes retain their shapes and remain separate
upon freezing, use the open-freeze or dry-freeze method to freeze food quickly
on all sides. Place a baking sheet lined with parchment paper or plastic wrap
in the freezer and chill for 10 to 20 minutes. Place the food in a single layer
on the lined baking sheet, leaving about 1 inch between the pieces, and freeze
for about 1 hour or until solid. Then pack in plastic freezer bags,
vacuum-sealed bags, or airtight freezer-safe plastic containers and return to
the freezer. Be sure to mark the
packages or containers with their contents and the date.
Do Not Freeze these
Foods
Most individual
ingredients can be frozen. However, some foods simply aren't freezer friendly:
1) Raw eggs in the
shells will expand and crack.
2) Hard-boiled eggs go
rubbery.
3) Vegetables with a
high water content, such as lettuce, cucumber, bean sprouts and radishes, go
limp and mushy.
4) Soft herbs, like
parsley, basil and chives, go brown.
5) Egg-based sauces,
such as mayonnaise, will separate and curdle.
6) Plain yogurt,
low-fat cream cheese, single cream and cottage cheese go watery.
What
Containers to Use?
Choose packaging materials that
will protect the food’s flavor, color, moisture content, and nutritional value
from the dry climate of the freezer. Containers should:
1) Not become brittle and crack at low temperatures. Look for the
freezer symbol, often a snowflake, to indicate that it is freezer safe.
2) Be durable, leak proof, and easy to seal and
mark.
3) Be oil, grease, and water resistant (no uncoated
paper containers).
4) Protect against absorption of outside flavors
and odors.
A. Glass and Ceramic: If
using glass containers, choose
dual-purpose types that are designed for freezing and also are heatproof. Pyrex
and Simax are brands made from boro silicate glass, which cannot go from freezer
to hot oven immediately—the dish must stand at room temperature for at least 30
minutes, as the sudden heat change may cause it to break. Dishes with tempered
glass such as Anchor Hocking and Duralex must be completely thawed before
placing in a hot oven.
If you’re using glass
jars to freeze sauces, soups, or stocks, be sure to leave at least a 3⁄4- to 1-inch space at the top, as the water in
the recipe will expand and may cause the glass to break if filled too high. There
are also many brands of freezer to-oven-to-table ceramic dishes, such as Corning
Ware and GlassLock
tempered storage containers.
These are especially good for baked pastas and casseroles, as they can be placed
in the oven straight from the freezer, and then brought to the table. Be sure
they are suitable for freezer use.
B. Plastic: Make
sure the containers close tightly and securely and are made of plastic that
will not become brittle at a low temperature; look for the snowflake symbol on
brands such as Sistema, Klip It, or Lock & Lock. All three have a clipping
system for closing the top. Plastic containers are good for foods that have
been frozen with the open-freeze or dry-freeze method, as they protect more fragile
items, such as meringues, profiteroles, and pastries, from being damaged or
crumbled by other bags and containers of food. They also allow you to take out
and use as much food as required, resealing the remainder in the plastic
container for another day.
C. Plastic Freezer Bags: Be
sure to use only plastic bags that are labeled for freezer use. Once the bag is
filled, try to squeeze out as much air as possible in order to prevent ice
crystals from forming around the food in the bag. Once the air is squeezed out,
tightly close the bag, either by sealing with the attached zipper lock, or by
twisting the top of the bag and fastening tightly with a freezer clip or
plastic-coated wire twist-tie. Bags are best used for small to medium
quantities; it’s faster to thaw two smaller bags than it is one large one.
When using freezer
bags, ideally freeze flat until solid, then store upright or stack with other
frozen foods. Food that is frozen flat will thaw much more quickly than food
that is frozen in one big lump.
D. Vacuum-Sealed Bags: These
excellent bags work by sucking the air
out of the filled bag and heat sealing it at the same time, thus completely
eliminating the possibility of freezer burn and flavor deterioration.
What is
Freezer Burn?
Freezer burn
is a condition that occurs when frozen food has been damaged by dehydration and oxidation, due to air reaching the food. It is generally
induced by substandard (non-airtight) packaging. The condition is primarily
caused by sublimation. Water
evaporates at all temperatures, even from the surface of solid ice. If air
adjacent to ice is cold enough (so the ice won't melt) and the air is dry
enough, water molecules go directly from solid phase (ice) to gaseous phase (vapor)
without going through a liquid phase. When the constantly vibrating water
molecules in foods stored in a freezer migrate to the surface, crystals of ice
outside of the solid food are formed, and some water molecules escape into the
air (by sublimation). The meat parts now deprived of moisture become dry and shriveled
and look burnt. In meats, air can cause
fats to oxidize.
Meats and vegetables
stored in a manual-defrost freezer will
last longer than those stored in automatic-defrost freezers. That is
because the temperature of a manual defrost freezer remains closer to 0 °F/-18
°C while the temperature of automatic
defrost freezers fluctuates, and because automatic-defrost freezers have
drier air, thus the rate of sublimation increases.
Using sealed bags
method is optimal, you will have to buy the vacuum-sealing
machine and the special bags.
Items such as burgers, meatballs, and fishcakes must be frozen solid first (by
the open-freeze or dry-freeze method) or they will become misshapen when the
bag is sealed.
Keep the temperature in your freezer below 0 degrees F (-18 degrees C). Freezer burn only happens when
temperatures fluctuate above 0 degrees F. Use a freezer thermometer to make
sure the freezer is cold enough.
Package food tightly.
When the surface of food is exposed to air, the water molecules have a chance
to sublimate and migrate. When you're getting food ready for the freezer, try
to make sure as little of the surface is exposed as possible.
Freezer
burn does not make food unsafe,
merely dry in spots. It appears as grayish-brown leathery spots and is caused
by air coming in contact with the surface of the food. Cut freezer-burned
portions away either before or after cooking the food. Heavily freezer-burned
foods may have to be discarded for quality reasons.
Meat
stews
need to be completely cold with their juices well jelled together; otherwise
the moisture will be drawn out and clog the machine, as well as prevent a
successful seal to the bag. The vacuum
seal is also good for sealing cuts of raw meat,
chicken, and fish. The drawback to this system is that once the bag
is opened, you either must thaw all the food inside or reseal the portion you
are not using immediately.
E. Plastic Wraps and Aluminum Foil: Good
materials for wrapping meats and other large or irregularly shaped foods include
freezer-coated paper, plastic wrap, and heavy-duty aluminum foil. You’ll notice
that freezer paper is shiny on one side; place food directly on the shiny side.
Waxed paper can be used
to keep food separate in freezer safe containers. Freezer-safe plastic wrap allows
for a super-tight wrap. For extra safekeeping, after being wrapped in plastic freezer
wrap, food should then additionally be wrapped in either heavy-duty foil or placed
in a plastic freezer bag.
Do not use regular plastic wrap, which is porous and can lose its clinging qualities under
sustained cold temperatures, possibly allowing foreign odors to penetrate the
food. Also refrain from using regular-weight foil, as it becomes brittle at low
temperatures. Avoid
parchment and greaseproof paper, which becomes soggy on freezing.
How
to Organize Your Freezer?
Freezers should be kept at 0°F/−18°C. If your freezer or fridge-freezer does
not show the exact temperature digitally, consider keeping a
refrigerator/freezer thermometer in the freezer. If the temperature rises above
0°F/−18°C, turn down the dial in the refrigerator/ freezer to
lower the temperature. Look for stars on the freezer compartments. The stars indicate
the temperature of the compartment and how long food may safely be stored
there.
1) One
star (21°F/−6°C) is fine for making ice cubes and is sufficiently cold to keep
food for three or four days.
2) Two
stars (10°F/−12°C) stores food for fifteen to twenty days.
3) Three
stars (0°F/−18°C) will keep food safe for up to three months.
4) Four
stars (below 0°F/−18°C) means that the compartment provides
the ideal conditions for freezing fresh and precooked foods. Learn about food
freezer storage-life at... Food Storage
Shelf Life Chart.
Once food is placed in
appropriate freezer storage containers, try to avoid throwing it in the freezer
at random. It is well worth making the time to package, date, and label food
and to place it so that you can see right through to the back or bottom of the
freezer. If the freezer is deep, keep a list on the door that itemizes the
contents. Use a nonmetal rack to
create shelves, so that everything is not simply piled up on top of everything
else and so that you can access items more easily. For maximum efficiency, keep
your freezer at least 75 percent full; otherwise you’ll lose the cold air each
time the freezer is opened.
Is Frozen Food
Safe?
Food stored constantly at 0°F will always be safe.
Only the quality suffers with lengthy freezer storage. Freezing keeps food safe
by slowing the movement of molecules, causing microbes to enter a dormant
stage. Freezing preserves food for extended periods because it prevents the
growth of microorganisms that cause both food spoilage and food borne illness.
How to Freeze
Vegetables?
Freezing is the best
way of preserving a season's bounty to enjoy later. When properly frozen,
vegetables retain all their flavour and nutrients. The best method of freezing
is the same for peas, runner, French, dwarf and broad beans, asparagus and
broccoli.
1) Freeze vegetables for between 3 and 6 months. Vegetables will
retain their flavor and appearance if frozen and thawed within this time
period.
2) Blanch certain vegetables before freezing. This method will
prevent the enzymes present in vegetables from causing the vegetables to lose
their flavor and color.
3) Determine the amount of time each
vegetable type needs to boil. Asparagus, broccoli, beans, and cabbage will take
up to 3 minutes; whereas Brussels sprouts, large carrots, and slices of eggplant
will take up to 5 minutes.
3) Bring a pan of water to boiling,
then place small portions of vegetables into the boiling water.
4) Let the vegetables boil for the
proper amount of time, then transfer the vegetables immediately to a bowl of
cold ice water.
5) Dry your vegetables with a paper
towel, then store them in bags or containers in the freezer.
How to Freeze Meats?
1) Trim the fat and bones from all meat. This will release excess
fluids and gases that are present in the meat and help retain its freshness and
quality during freezing.
2) Store meats in the freezer for the appropriate length of time.
Each meat type requires different lengths of freezing time depending on the
amount of fluids present in the meat.
3) Keep sliced and shaved meat and
hotdogs in the freezer for up to 2 weeks.
4) Store cured ham and bacon in the
freezer for up to 1 month, cooked meats for up to 2 months, and ground meat in
the freezer for up to 3 months.
5) Store meats from large cuts, such
as steaks, in the freezer for up to 12 months.
6) When thawing, ensure that stuffed (seasoned), poultry or rolled meat has
thawed right to the center before cooking.
How to Freeze
Seafood?
1) Cut large or whole fish into small portions. This will retain the
overall freshness of the fish and give you the ability to clean and gut whole
fish before freezing.
2) Create a protective icy coating for the fish. An additional
coating of ice on your fish will help guarantee its freshness and eliminate
odors that the fish may emit during freezing.
3) Remove your fish from the freezer
after it has frozen completely, then dip it into water before refreezing. This will
allow a new layer of ice to form and cover the fish.
4) Freeze your fish for up to 3 months. If you are freezing oysters,
you can store them in the freezer for up to 6 months.
5) When thawing, ensure that that seafood has thawed right to the center before
cooking.
Related Post: How to Choose the Best Freezer
How to Thaw Frozen
Foods?
1) Microwaves are handy for thawing.
Check your user manual for specific instructions. Here are some handy tips for
thawing different foods at room temperature and in the fridge.
2) Foods
with a low moisture content (such
as cakes, muffins and biscuits) can be thawed at room temperature.
3) Remove and discard the plastic wrap
or other packaging before thawing - otherwise the ice crystals that form on the
surface during freezing will form a pool of liquid as they melt, which can
cause cakes and muffins to become soggy.
4) Foods
with a medium moisture content (such
as fresh pasta, sliced bread, frozen meals and frozen veggies) can be reheated
immediately after being taken out of the freezer.
5) Foods
with a high moisture content (such
as meat, chicken, fish, fruit and cooked liquid-based dishes) need to be thawed
in the fridge to prevent bacteria growing.
6)
Place meat on a plate or in a container to catch any juices. Thaw in the fridge for 24-48
hours. This allows the ice crystals to break down slowly and helps retain the
texture of the meat.
7) Be as gentle as possible when
thawing frozen fruit. Fruit has high water content, so place, in a single
layer, on a baking tray lined with paper towel to absorb excess liquid as it
thaws.
Does Freezing
Destroy Bacteria & Parasites?
Freezing
to 0°F inactivates any microbes—
bacteria, yeasts and molds — present in food. Once thawed, however, these
microbes can again become active, multiplying under the right conditions to
levels that can lead to food borne illness. Since they will then grow at about
the same rate as microorganisms on fresh food, you must handle thawed items as
you would any perishable food.
Trichina and other parasites can be
destroyed by sub-zero freezing temperatures. However, very strict
government-supervised conditions must be met. Home freezing cannot be relied
upon to destroy trichina. Thorough cooking, however, will destroy all
parasites.
Freshness and quality
at the time of freezing affect the condition of frozen foods. If frozen at peak
quality, thawed foods emerge tasting better than foods frozen near the end of
their useful life. So freeze items you won't use quickly sooner rather than
later. Store all foods at 0° F or lower to retain vitamin content, color, flavor
and texture.
Nutrient Retention
in Frozen Food
The freezing process
itself does not destroy nutrients. In meat and poultry products, there is
little change in nutrient value during freezer storage.
Effect of Food Enzymes
Enzyme
activity can lead
to the deterioration of food quality. Enzymes present in animals, vegetables,
and fruit promote chemical reactions before and after harvest, such as
ripening. Freezing only slows the enzyme activity that takes place in foods. It
does not halt them.
Enzyme activity does
not harm frozen meats or fish and is neutralized by the acids in frozen fruits.
But most vegetables that freeze well are low acid and require brief, partial
cooking to prevent deterioration. This is called "blanching." For successful freezing, blanch or partially cook
vegetables in boiling water or in a microwave oven. Then rapidly chill the
vegetables prior to freezing and storage. Consult a cookbook for timing.
References:
1997. Quality in Frozen Food.
Springer; 1997 edition. ISBN-10:
0412070413
Gould, G. W. 2012.New Methods
of Food Preservation. Springer;
Softcover reprint of the original 1st ed. ISBN-10: 1461358760
James,
S J, and C. B.
James MA DM FRCS FRCOphth.2002. Meat Refrigeration (Woodhead Publishing
Series in Food Science, Technology and Nutrition) Woodhead Publishing; 1
edition. ISBN-10: 1855734427
Mallett, C.P. 1992.Frozen Food
Technology. Springer;
Softcover reprint of the original 1st ed. ISBN-10: 1461365767
Neville,
Kat and
,
Smith, Durward S. , Jerry N. Cash ,
Wai-Kit Nip and Y. H. Hui 1997. Processing
Vegetables: Science and Technology. CRC Press; 1 edition. ISBN-10:
1566765072
Sun, Da-Wen. 2011.Handbook of
Frozen Food Processing and Packaging, Second Edition (Contemporary Food
Engineering). CRC
Press; 2 edition. ISBN-10:
1439836043
1969. Quality
and Stability of Frozen Foods. John
Wiley & Sons Inc. ISBN-10:
0471897906
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