Class I. Meats intended for immediate consumption and passed to the consumer within, at the most, one week after slaughter. Class II. Cold storage meats, which are placed in refrigerators, frozen, and kept for a longer period than one week. There is evidently also a limit to the length of time which meat should remain in cold storage, no matter how low the temperature may be, since the action of organisms which produce decay cannot be entirely overcome. The exact limit at which frozen meats can be kept without becoming inedible has not been determined. Without this determination, however, it is advisable that such limit should not be approached. Inasmuch as the supply of fresh meat is practically uniform, or can be made so by the dealer therein, there seems no good reason for the storage of meat in refrigerator compartments for a longer time than is necessary for transportation and a reasonable time thereafter for passing into consumption, except in cases of emergency. It might be safe to say that no meat should be kept in a cold storage warehouse longer than a month after its reception. Numerous instances might be cited in which meat may be kept for a much longer time, but the question for the consumer is not how long a while meats can be kept but how soon they can be placed in his hands. In this connection it should not be forgotten that it is the opinion of perhaps the majority of hygienists and connoisseurs that fresh meat, especially beef, improves for a certain length of time in cold storage. It is probable that the fresh beef which is served to the people of the United States is on an average a month old, and is said to be improved by keeping this length of time. This is a question, however, which is still undetermined, and it deserves a further investigation. Under present conditions it is well to know the truth respecting these matters and to realize that the fresh meat we get, such as beef and mutton, is not direct from the shambles but has been kept for at least four weeks in cold storage.
Effect of Long Cold Storage.
—It has been stated in semi-scientific publications that the flesh of a mammoth incrusted in polar ice and presumably thousands of years old has been found to be intact and edible. This story, lacking corroboration, is hardly in harmony with known facts. The author had the opportunity of examining a quarter of beef which had been kept frozen in a warehouse for more than eleven years. This meat was found to be wholly inedible. It had an unpleasant and mummy-like odor, was light in fiber and color, having evidently lost a large part of its weight, and was of a character wholly unsuitable for consumption. This fact appears to show that eleven years is too long a time in which to keep meat frozen. In fact, it is scarcely worth while, from a practical point of view, to discuss so long a limit. Only the necessary time for the preparation and transportation of the meat is to be considered, and the sanitary laws of the nation, states, and municipalities should undoubtedly regulate the time of cold storage and see that all packages of meat exposed for sale are plainly tagged as to the date of slaughter, in order that the consumer may know.
In the consideration of the subject of preserved meats there are excluded all meats delivered in the fresh state for consumption and meats kept in cold storage in a fresh state during the necessary time of preparation and transportation say, on the whole, from four to eight weeks. Meats kept longer than this may generally be considered as preserved meats, even when cold is the only factor active in their preservation.
Method of Preserving Meats.
—Aside from cold storage there are four methods in vogue for preserving meats. These may be classified as follows: (1) Curing with the aid of condimental substances; (2) treatment with chemical and non-condimental preservatives; (3) sterilization with heat; (4) drying. These all except the second may be regarded as legitimate means of preserving meats.
Curing with Condimental Substances.
—This method of preserving meat has been practiced from the remotest antiquity. The chief condimental substances employed are salt, sugar, vinegar, and wood smoke. With the proper technical skill and knowledge of the process, meats can be preserved in this way, and at the same time aromas and flavors developed which are considered most agreeable by the consumer and which give an additional value to the product. It is not to be claimed in any case that condimental preservatives add anything to the nutritive value of the product, except in so far as condiments themselves aid the digestion by exciting in a perfectly proper way the activity of the glands which secrete the digestive ferments.
It is not the purpose here to describe the technical processes used. In general it may be said that the application of salt is the first process, and this is done as soon after the slaughter as possible to secure the proper cooling of the carcass, usually from twenty-four to forty-eight hours. The meat, properly cut into the forms known to commerce, is carefully packed and heavily salted, and allowed to remain for some time in contact with the salt or with the brine which is produced therefrom. The salt penetrates to the interior of the flesh and hardens, to some extent, the tissues, abstracting water therefrom, and, without being wholly germicidal in character, prevents the introduction of eggs of insects and the development of ordinary germ life. The salt, however, does not entirely inhibit the enzymic action which tends to ripen the meat and make it more palatable. It naturally gives to the meat the salty flavor which is demanded by the taste in a preparation of this kind.
Sugar is used, if at all, always in connection with salt as a preservative for meats. It may be employed in the pure state, but is usually the yellow or low-grade sugar or molasses. It gives to the preserved meat, especially ham, a flavor and quality much appreciated by the consumer.