Freezing Methods

Quick freezing processes are designed to take food through the temperature range from 0 °C to −5 °C (32 °F to 23 °F) in a few minutes, since this is when most ice crystals form. The less time they have to form, the smaller they will be and the less damage they will do to the cell structure of the food. The smaller the pieces of food, the faster they freeze. Several methods are currently used for items of different sizes.

Air blast freezing is the most used technique. It freezes smallish objects, such as packets of frozen vegetables, quickly and uniformly. The food is frozen on refrigerated trays by a blast of chilled air at −12 °C (10 °F), after which it can be cooled more slowly to the storage temperature of a commercial freezer, −20 °C (−4 °F). A variant used for very small objects, such as loose peas, is fluid bed freezing, where the food travels along a belt pierced with holes through which chilled air is blown, lifting the food so that it is frozen in mid-air.