Michigan State University Extension
Preserving Food Safely - 01600506
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.