This post is also available in: Persian
Freezing is one of the easiest, quickest, most versatile and most convenient methods of preserving foods. Properly frozen foods maintain more of their original color, flavor and texture and generally more of their nutrients than foods preserved by other methods.
Good freezer management is important. The following tips will help you get the most of your freezer dollar.
• Place your freezer in a cool, dry area where the temperature is constant.
• Keep your freezer at least ¾ full for efficient operation.
• Continue to use and replace foods. Do not simply store them.
• Open the freezer door as rarely as possible.
• Make proper use of energy saving features on your freezer.
• Keep door seals clean and check for proper sealing. Replace when necessary.
• Defrost manual freezers regularly.
• Keep the condenser coils clean.
The condition of the food at the time of freezing will determine the final quality of the frozen food. Frozen food can be no better than the food was before it was frozen. Freezing does not sterilize foods as canning does. It simply retards the growth of microorganisms and slows down chemical changes that affect quality or cause food spoilage.
Freezing, heating and chemical compounds can control enzyme actions. Freezing slows enzyme activity so that many frozen foods, such as meats and many fruits, will keep satisfactorily with little or no further treatment.
Enzymes in vegetables are inactivated by heat during the recommended blanching process.
Oxygen in the air may cause flavor and color changes if the food is improperly packaged.
Microorganisms do not grow at freezer temperature, but most are not destroyed and will multiply as quickly as ever when the frozen food is thawed and allowed to stand at room temperature.
The formation of small ice crystals during freezing is desirable. Fast freezing is the most practical way to form small ice crystals. Large ice crystals associated with slow freezing tend to rupture the cells, causing an undesirable texture change.
Maintain temperature of 0 degrees Fahrenheit or less to keep frozen foods at top quality. The storage life of foods is shortened as the temperature rises. For example, the same loss of quality in frozen beans stored at 0 F for one year will occur in three months at 10 F, in three weeks at 20 F, and in five days at 30 F.
Fluctuating temperatures result in growth in the size of ice crystals, further damaging cells and creating a mushier product. Changes in temperature can also cause water to migrate from the product.
Improperly protected food will lose moisture, color, flavor and texture. Ice crystal evaporation from an area at the surface results in freezer burn, which is a dry, grainy, brownish area that becomes tough. Freezer burn does not render a food unsafe, only less desirable.
The prime purpose of packaging is to keep food from drying out and to preserve nutritive value, flavor, texture and color. Labels on packages will say if the product is suitable for freezer storage. A good packaging material should have the following characteristics:
• Moisture/vapor-proof or at least moisture resistant.
• Made of food grade material, i.e. designed to be used for food products.
• Durable and leakproof.
• Doesn’t become brittle and crack at low temperatures.
• Resistant to oil, grease or water.
• Protect foods from off flavors and odors.
• Easy to fill and seal.
• Easy to mark and store.
The packaging you select will depend on the type of food to be frozen, personal preference and availability. For satisfactory results, do not freeze fruits and vegetables in containers larger than one-half gallon.
Packaging not sufficiently moisture/vapor-resistant for long-time freezer storage includes ordinary waxed paper and paper cartons from ice cream and milk.
Rigid containers are made of plastic, glass, aluminum and heavily waxed cardboard and are suitable for all packs. These are often reusable. Straight or tapered sides on rigid containers make it much easier to remove frozen foods.
Glass jars used for freezing should be made for the purpose. Regular glass jars may not withstand the extremes in temperature. Do not use regular, narrow-mouth canning jars for freezing foods packed in liquid. Expansion of the liquid could cause the jar to break at the neck.
Cans, such as shortening and coffee cans, are good for packaging delicate foods. Line the can with a food-storage bag and seal the lid with freezer tape because they are not airtight.
Baking dishes can be used for freezing, heating and serving. Dishes may be covered with a heavy aluminum foil taped with freezer tape. To reuse the baking dish after the food is frozen, wrap the food in casserole-wrap fashion. (See “Food Freezing Basics: Methods of Wrapping.”)
Ice cube trays are good for freezing foods in small amounts. Freeze food until firm and then transfer to freezer bags.
Bags and sheets of moisture/vapor-resistant materials and heavy-duty foil are suitable for dry packed vegetables and fruits, meat, fish or poultry. Bags can also be used for liquid packs. Protective cardboard cartons may be used to protect bags and sheets from tearing and to make stacking easier.
Laminated papers made of various combinations of paper, metal foil and/or cellophane are suitable for dry packed vegetables and fruits, meats, fish and poultry. Laminated papers are also used as protective overwrap.
• Cool all foods and syrup before packing. This speeds up freezing and helps retain natural color, flavor and texture of food.
• Pack foods in quantities that will be used at one time.
• Most foods require head space between the packed food and the closure for expansion as the food freezes. Loose packing vegetables, such as asparagus and broccoli, bony pieces of meat, tray-packed foods and breads, do not need head space.
• Pack foods tightly to cut down on the amount of air in the package.
• Run a nonmetal utensil, such as a rubber scraper handle, around the inside of the container to eliminate air pockets.
• When wrapping food, press out as much air as possible and mold the wrapping as close to the food as possible.
• When packing food in bags, press the air from the bags. Beginning at the bottom of the bag, press firmly moving toward the top of the bag to prevent air from re-entering or force the air out by placing the filled bag in a bowl of cold water taking care that no water enters the bag. Seal either method by twisting and folding back the top of the bag and securing with string, good quality rubber band, strip of coated wire or other sealing device. Many bags may be heat sealed, and some have a tongue-in-groove seal built in.
• Keep sealing edges free from moisture or food so they’ll make a good closure.
• When using tape, it should be freezer tape, designed for use in the freezer. The adhesive remains effective at low temperature.
• Label each package with name of product, date, amount and any added ingredients. Use freezer tape, freezer marking pens or crayons, or gummed labels made especially for freezer use.
• Freeze foods at 0 F or lower. To facilitate more rapid freezing, set the freezer at minus 10 F about 24 hours in advance of adding unfrozen foods.
• Freeze foods as soon as they are packaged and sealed.
• Do not overload the freezer with unfrozen food. Add only the amount that will freeze within 24 hours. This is usually 2 or 3 pounds of food per cubic foot of storage space. Overloading slows down the freezing rate, and foods that freeze too slowly may lose their quality.
• Place packages against freezing plates or coils. Leave space between packages so air can circulate freely. After freezing, store packages close together.
• Arrange packages so you use those that have been in the freezer the longest first.