Conservation 3. Freezing

As a method of conservation, the freezing of foods was used, probably, since long time ago, in the regions of the world where the climate allowed that the nature was seized as refrigerator. In the Northern of Sweden, especially, among the Lapps, even today, the frozen meat is guarded in the open air.

The starting of the technical freezing usually is fixed about 1882, when the brigantine “Dunedin” sailed from New Zealand to England, loading frozen meat. In 1911, A. J. Ottensen registered the patent of a method for the quick freezing of fish and, about 1930, C. Birdeye contributed remarkably for improving in that matter. That researcher built the first freezer of blocks. The development of that technique continued advancing, and, since 1960, the technique for continuous and entirely automatic freezing imposed. The beginning of the freezing is based in the formation of microorganisms which will not be possible from an enough low temperature. The used method in the freezing is very important for the quality of the foods. Generally, the freezing must effectuate with the quickest possible method with the aim of avoiding the formation of grand crystals of ice.

The temperature of normal storage in the commercial places is -30º C; in the fridge counters and in the abattoirs, of -18ºC. It is required to notice that the microorganisms develop in the defrosted foods the same way in the fresh foods.

An important field for the employment of the freezing is the seasonal storage: it consists in freezing the overage of the diverse seasonal products for giving showing those in periods when it is not possible to find them as fresh or when the production is diminished. That method of storage is used mainly with the meat, the butter and the herrings.

In the industry of food, there is also the employment of an intermediary storage of frozen raw materials for later use, mainly, of vegetables and greens which can only be collected during a short period of the year. For the consumer, the most important field of use of the frozen products is the industrial freezing of tinned foods, which assortment rises constantly and fulfill the counters of the supermarkets and the domestic freezers. There is also the use of the domestic freezing, which is an efficient and commodious system for the conservation and the domestic storage of determined products.