How Cold Preserves Food

As the molecules move slower there is an important effect on the bacteria that are present in most foods. Cold or low temperatures slow up the growth of these bacteria and foods do not spoil as fast. Slowing the movement or cooling of the molecules tends to make all organisms more sluggish. Spoiling of food is actually the growth of bacteria in the food. 

If the bacteria can be kept from increasing, the food will be edible for a longer Period of time. Since most foods have considerable water content, the food must be kept just above freezing temperatures (32 F). If food is frozen slowly at or near the freezing temperature of water; the ice crystals formed are large and their growth ruptures the food tissues. 

When the food melts or defrosts, it spoils rapidly and its appearance and taste are ruined. Fast freezing at very low temperatures (0 to -15 F.) forms small crystals and the food tissues are not injured. Food freezers are maintained at or below 0 F., and food placed in them is frozen very quickly. 

It is well to keep in mind during the ensuing chapters that the average correct refrigerating temperature for domestic refrigerators is between 35 F. and 45 F.. And to make ice, a temperature lower than 32 F. Is needed.