How to Quick Freeze Food

Most foods can be preserved for a long time if they are frozen quickly and kept at a low temperature until ready for use. Slow, natural freezing destroys food because the low temperatures draw all the water from the tiny cells of the food, affecting color and flavor. Clarence Birdseye invented a way for quick freezing in 1921. This method prevents breakage of the cell walls because the freezing process is so fast. Thus, in quick-frozen food most of the flavor, color and firmness is retained. There are 3 methods to quick freeze food--by immersion in a freezing solution; by indirect contact with the freezing solution; and by blasts of cold air.

Difficulty:

Moderate

Instructions

1. Immersion is a process in which food is wrapped in airtight and watertight coverings and soaked in a solution of brine, at a temperature of about 0 degrees F. Sometimes the food is simply placed in metal pans and floated on top of the freezing liquid.

2. Indirect contact quick freezing is the method used by most commercial frozen-food manufacturers and by housewives. A multi-plate machine is used which has many hollow aluminum plates enclosed in an insulated box. The walls of these plates are made of winding tubes which ammonia and brine is circulated. Packages of fish or meat which are two inches thick can be frozen in a multi-plate machine in less than an hour and a half. Fruit and vegetable packages of the same size require about two hours freezing.

3. Cold-air quick freezing requires not only a freezing solution, but also blowers to circulate the air. Air is circulated over or through the freezing solution until the air is zero degrees or lower and then is blown across the wrapped packages of food. Many refrigerators are equipped with small quick-freeze compartments. Families which cannot afford home freezing units often rent a commercial food locker close to their homes. These lockers hold about 6 cubic feet of food.

4. Use the home method for quick freezing; it is very much like the multi-plate method, but on a smaller scale. Usually the home freezing unit is large enough to hold 200 lbs. of packaged food. It is made in two parts, one for quick freezing the food and the other for storage. The best types of home freezers have one large door in the front, and separate doors inside for each storage shelf and for the freezing compartment.

5. Follow certain rules for best results in quick freezing. Fruits and vegetables must be harvested when they are ripe enough for table use, and they must be cleaned thoroughly. Both fruits and vegetables continue to take up carbon dioxide after they are harvested. So vegetables must be blanched and fruits need coated by dry sugar or sugar syrup.