Meat, in the sense the word is here used, includes beef, mutton, pork, and an occasional allowance of wild game. Chemically considered, meat may be divided into two classes, namely (1) flesh or lean meat, and (2) animal fats. The former will be first considered.

1. Flesh Or Lean Meat

Lean meat is composed of the muscles of the animal. Approximately it is 70 per cent water, 20 per cent protein, and 10 per cent fat. The protein is composed of connective tissue, which is a tough, fibrous substance that forms tendons, and holds the muscle-cells in place. Chemically, connective tissue is formed of albuminoids, which were discussed in Lesson IV (Chemistry Of Foods). These substances are somewhat difficult to digest, and are not of very great importance in the human body, as they cannot take the place of true proteid in tissue-formation.

Composition of lean meat.

The percentage of connective tissue in flesh depends upon the cut of the meat. As every housewife knows, the cheapest cuts of meat contain a larger amount of this material.

The gelatin of commerce is a manufactured product derived from the connective tissue of animals.

Other forms of protein are globulin and myosin, which form the actual muscle-substance. These elements form perhaps three-fourths of the entire proteid of the animal, and are the most valuable substances of flesh food. A very small portion of meat proteids is formed by the free albumins of the blood, which are mechanically retained in the muscle-cells, the purpose of which is the nourishment of the animal, and therefore are not unwholesome as food..

Another class of nitrogenous substances found in flesh foods is called meat extractives. Though they exist only in quantities of from one to two per cent of the weight of the flesh, they are the most interesting from the standpoint of chemistry, because they are found only in flesh foods, and are products only of cell life, hence not wholesome as food. They are composed of urea, uric acid, creatin, etc., and are similar or identical to the waste-products of human cell metabolism. The amount of these substances contained in flesh depends upon the condition of the animal at the time of slaughter, being much greater in animals slain after the chase, or laboring under fear or abuse. The chemical composition of the different cuts of meat does not vary greatly, except in a greater or less per cent of fat, and no chemical calculation can compute this accurately, as the fat in every cut of meat varies widely.

Meat extractives and their composition.

Beef and mutton are comparatively the same in both nutritive value and popularity, but the use of pork has been generally condemned the world over. The reason for this is probably explained by prejudices of tradition and religion, rather than by scientific or hygienic knowledge. The prejudice against swine because of the filthy habits of the animal is more a matter of sentiment than of science. It is sometimes the custom among farmers to confine hogs in a pen, and to feed them upon swill and garbage. This makes of the animal a filthy creature. However, when left in the open fields or woods, they are as cleanly in their habits as any of their brother animals. Corn and alfalfa-fed pork is equally as wholesome as beef or mutton, when prepared in a similar manner, and eaten in temperate quantities, while the hog fattened upon acorns and herbs, in his native habitat (the woods), is much more healthy, and his flesh really superior to most of his brother animals.

Prejudice against the hog.

2. Animal Fats

The use of animal fats as food is a very ancient custom, especially among the northern tribes. This custom was once justified owing to the necessity for the consumption of a liberal amount of fats in cold countries, but in this country where our marvelous system of international transportation places at the door of every northern home the delicious fats from the olive orchards of Italy, France, and Spain, the refined oil from the cottonseed, and more than a dozen varieties of nuts, including the humble peanut, there is but little necessity for the use of animal fats except in the form of butter and cream.

Perhaps the most injurious way in which animal fats are used is in the process of frying, which is much practised in southern countries in the preparation of other food. The chemical change which takes place in fats, when treated in this manner, renders them exceedingly indigestible, and almost wholly unfit for food.

Animal fats not a necessity.

That per cent of animal fats contained in the ordinary meat diet is quite as wholesome as any other element of nutrition secured from animal sources. However, with the splendid supply of vegetable fats civilized people have to draw upon, the use of animal fats cannot be recommended in any form except that of cream and butter, and when we consider the expense of these by comparison with many pure vegetable fats, our sense of ordinary economy would bid us discard them.

The chief distinction between animal and vegetable fats is in the proportion of olein compared with stearin and palmitin. The proportion of the two latter fats is much greater in fats of domestic animals than it is in the human body; this is especially so of tallow. For this reason vegetable fats, which are of a more liquid nature, are more desirable than those of animal origin, especially where we wish to add fatty tissue to the body.

Chemical change in frying fats.

Cold Storage Of Meat

A very small amount of the meat produced in this country at the present time is consumed near its place of slaughter. Cold storage plants and refrigerator cars have been constructed for the purpose of preserving meats until they can reach their destination, and to hold them awaiting market advances for the benefit of packers and tradesmen.

Meat in cold storage is slowly undergoing a form of decomposition which is evidenced by the fact that cold storage meat decays much more rapidly upon its removal from storage than do the same cuts of fresh meat.

Chemical difference between animal and vegetable fats.

The process of ripening meat in rooms of varying temperatures depends upon this form of decomposition. The natural enzyms of the meat, and the bacteria contained therein, digest a portion of the proteids, forming nitrogenous decomposition products, similar to the above-mentioned meat extractives. Ripened or storage meats contain a much larger per cent of this group of compounds than does fresh meat.

The high flavor and "peculiar rich taste" of ripened meats is produced by these decomposition products, while the decay of the gelatinoid or connective tissue is the primary reason for its tenderness. There are certain species of bacteria that produce more poisonous waste-products than others, and this occasionally causes the development of ptomains in storage meat.

Decomposition of cold storage meat "Ripened meat" a step toward decay.

The use of flesh as an article of food is fraught with many serious and scientific objections, but the use of cold storage or ripened animal products is to be condemned from every standpoint of hygiene. Nevertheless, if people insist upon using flesh foods, and economical conditions make it profitable to produce them far from their place of consumption, cold storage methods seem inevitable. The choice between storage meats and home-killed is, in its last analysis, a matter of selecting the lesser of two evils.