Enzymes in Foods and Food Preservation

BECAUSE agricultural production is seasonal while food consumptioji is steady, the storage of food in some edible form has always been one of mankind's greatest problems. Practically all natural foodstuffs except ripe seeds undergo decay unless measures are taken to prevent it. Dried fruits, pickles, preserves, cheese, and fermented drinks probably all have their origin in attempts at food preservation. Today there is an increasing tendency, due to the possibilities of cold storage, to keep foods in their natural state as long as possible. Cold storage in itself merely delays the natural ]3rocesses of decay, although when the temperature is extremely low the rate of destruction is very slow. Frozen meat, if it were Ivept cold enough, would probably last a great many years without 'agoing bad/' Defects such as poor flavor and appearance and loss of moisture are about the worst that might be expected. It has been reported that the flesh of prehistoric animals found frozen in the Arctic was eaten by dogs w^ithout any apparent ill effect. There are tw^o agencies that cause decay in natural—that is, unprocessed—foods: (1) Micro-organisms, which come from contamination, and (2) enzymes, w^hicli already exist in the living tissue. The number of micro-organisms can be greatly reduced by keeping things clean, but under no circumstances is it possible to get rid of the enzymes, because they were a part of the material while it was alive. Enzymes are curious special proteins built up by the plant for the purpose of accelerating the chemical reactions that must go on if the tissue is to live. After the death of the tissue man}^ such