1. SUMMARY

Freezing is the easiest, most convenient, and least time-consuming method of preserving foods. Depending on the final storage temperatures of down to -30°C, the materials can be stored for up to 1 year or about it.
  • Freezing stops the growth of microorganisms; however, it does not sterilize foods or destroy the organisms that cause spoilage. A few organisms may die, but once thawed to warmer temperatures, these organisms can quickly multiply.

  • Chemical changes affect quality or cause spoilage in frozen foods. One major chemical reaction is oxidation. If air is left in contact with the frozen food oxidation will occur even in the freezer. An example is the oxidation of fats, also called rancidity.

  • Enzymes are naturally present in foods and their activity can lead to the deterioration of food quality. Enzymes present in animal foods, vegetables and fruit promote chemical reactions, such as ripening. Freezing only slows the enzyme activity that takes place in foods. It does not halt these reactions which continue after harvesting. Enzyme activity does not harm frozen meats or fish, but browning can occur in fruits while they are being frozen or thawed.

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Dosya Türü: doc
Şifre:www.forumfood.net