Frozen food includes fruits, vegetables, meat, fish, poultry, eggs, dairy products, and cooked foods that are packaged, frozen at 0 °F. or lower, and stored at 0 °F. or lower. These products are intended for relatively long-term storage and, in most cases, will keep in storage for a year or longer without significant change. Generally, frozen products are more nearly like the fresh product in color and flavor than those preserved in any other way.
In the United States frozen foods have been available to the public in retail-size packages since about 1945; but certain products, such as berries and eggs, have been on the market for many more years in wholesale quantities. Locker plants were in use prior to World War II. More recently home-freezer cabinets have been manufactured to provide efficient cold storage for the home processor.
Before being packaged and frozen, vegetables and apple slices must be blanched in boiling water or steam and then cooled. Blanching inactivates enzymes that would otherwise cause deterioration. Vegetables that are normally served raw, such as lettuce, cabbage, and tomatoes, are not suitable for this type of preservation. Vegetables should be harvested when young and tender, and fruit should be ripened until its maximum sugar content has developed. After being harvested, fruits and vegetables should immediately be prepared for freezing, because delay will cause loss of quality.
Before being frozen and stored, meats should be wrapped in some type of moisture-proof paper or heavy-duty foil.
There is sound reasoning behind the usual warning against the re-freezing of defrosted foods. Cell changes caused by the freezing process allow rapid bacterial growth after defrosting; all defrosted foods should be used or cooked immediately to prevent spoilage.
