Page:Popular Science Monthly Volume 81.djvu/166

160 worthy of consideration in the decomposition of meat. Ferments, moreover, do not act at very low temperatures, although they are not destroyed and resume activity when meat is thawed.

Whether bacteria multiply at freezer temperature in liquid foods is problematical. It is well established that bacteria die gradually in ice so that after several months ice is practically sterile. Ice, however, offers little nourishment for bacteria, while meat contains plenty of food, which is available if water is present. Bacteria can not multiply in solid substances and therefore multiplication in frozen meat is impossible. It is reasonable to assume that bacteria will die in frozen meat as they do in ice. Conditions of frozen fish are quite similar to those of meat and poultry. A few investigations of this problem are available and, in substance, agree with the findings in frozen meat and poultry. The bacteriological aspect of cold storage meats is largely speculative and scientific investigations are much needed to throw light on the problems of cold storage.

In a general way the conclusions reached by those investigators who have worked on cold storage problems are that there is no appreciable difference in chemical composition between fresh meat and meat kept frozen for periods longer than two years. No progressive changes could be determined with precision. In regard to frozen poultry it has been stated that the changes in chickens in 24 hours at 65 to 75° F. are greater than in cold storage at 10° F. for 12 months. The changes taking place in cold storage for 12 months are comparable to storage in a house refrigerator for 5 days, or in the packer's chillroom at 32° F. for 15 days, this not being sufficient time to bring about the tenderness and flavor of so-called "ripened" meat. Most chickens bought in the market as fresh are of poorer quality than chickens frozen for 12 months, and are poorer than many kept in cold storage for 16 months.

The conclusion is inevitable that cold storage at 10° to 15° F. has no deteriorating effect on the condition of meats, poultry and fish for a period long enough to bridge over the time from one flush season to the next, that is to say, for about 12 months. The term "deterioration" is a vague one and is interpreted largely on the basis of individual opinion and taste. Some foods are not considered fit to eat unless they have "ripened," but the ripening process is nothing but a decomposition brought about by bacteria and molds. Cheeses of all kinds are permitted to ripen for various periods of time and the changes taking place during the ripening process are comparable from a chemical point of view to the so-called deterioration of meat. The most delicate and savory steaks are subjected to a ripening process, which consists in storing them for 30 to 60 days at a temperature of 32°-40° F. During this time the muscle fibers undergo changes, which render them more soluble and consequently more tender, palatable and digestible. This is