Michigan
State University Extension
Preserving
Food Safely - 01600506
10/13/97
Proper packaging for freezing is important to keep food
from drying out and to preserve food value, flavor, color
and pleasing texture.
All containers should be easy to seal and waterproof so
they will not leak. Packaging materials must be durable and
must not become so brittle at low temperatures that they
crack.
To retain highest quality in frozen food, packaging
materials should be moisture-vapor-proof to prevent
evaporation. Many of the packaging materials on the market
for frozen food are not moisture-vapor-proof, but are
sufficiently moisture-vapor-resistant to retain satisfactory
quality of fruits and vegetables during storage. Glass,
and rigid plastic are examples of moisture-vapor-proof
packaging materials. Most bags, wrapping materials, and
waxed cartons made especially for freezing are moisture-
vapor-resistant. Unsuitable containers include ordinary
waxed paper, and paper cartons from cottage cheese, ice
cream, and milk.
Rigid containers. Rigid containers made of glass,
plastic, tin, or heavily waxed cardboard are suitable for
all packs, and especially good for liquid packs. Glass
canning jars may be used for freezing most fruits and
vegetables except those packed in water.
Nonrigid containers. Bags and sheets of moisture-vapor-
resistant cellophane, heavy aluminum foil,
polyethylene, or laminated papers are suitable for dry-
packed vegetables and fruits. Bags also can be used for
liquid packs.
Bags and sheets are used with or without outer cardboard
cartons to protect against tearing. Bags without a
protective carton are difficult to stack. The sheets may be
used for wrapping such foods as corn-on-the-cob or
asparagus. Some of the sheets may be heat-sealed to make a
bag of the size you need. Sheets that are heat-sealing on
both sides may be used as outer wraps for folding paperboard
cartons.
Size
Select a size that will hold only enough of a fruit or
vegetable for one meal for your household.
Shape
Rigid containers that are flat on both top and bottom
stack well in a freezer. Round containers and those with
flared sides or raised bottoms waste freezer space.
Nonrigid containers that bulge also waste freezer space.
Food can be removed easily, before it is thawed, from
containers with sides that are straight from bottom to top
or that flare out. However, food must be partially thawed
before it can be removed from containers with openings
narrower than the body of the container.
Bags, sheets and folding paperboard cartons take up
little room when not in use. Rigid containers with flared
sides will stack one inside the other and save space in your
cupboard when not in use. Those with straight sides or
narrow top openings cannot be nested.
Sealing
Care in sealing is as important as using the right
container. Rigid containers usually are sealed either by
pressing on or screwing on the lid. Some rigid
cardboard cartons need to have freezer tape or special
wax applied after sealing to make them airtight and
leakproof. Glass jars must be sealed with a lid
containing composition rubber or with a lid and a rubber
ring.
Most bags used for packaging can be heat-sealed or sealed
by twisting and folding back the top of the bag and securing
with a string, a good quality rubber or plastic band, or
other sealing device available on the market.
Reuse
Glass and rigid plastic containers can be reused
indefinitely. It is difficult to reuse aluminum foil boxes,
because edges of lids and containers are folded over in
sealing.
Reuse of rigid cardboard cartons, unless plastic-lined, is
not generally advisable because cleaning is difficult.
Folding paperboard cartons used to protect an inner bag can
be reused.
Cost
When you compare prices of the containers available in
your locality, consider whether they will be reusable or
not. If containers are reusable, a higher initial cost may
be a savings in the long run.
Care of packaging materials
Protect packaging materials from dust and insects. Keep
bags and rolls of wrapping materials that may become
brittle, such as cellophane, in a place that is cool and not
too dry.
Freezing accessories
Check on other items that help make packaging easier.
Some containers are easier to fill if you use a stand and
funnel. Special sealing irons available on the market for
heat-sealing bags, wrappers, and some types of paper
cartons. With some sealing irons, a small wooden block
or box makes sealing of bags easier and quicker.