CHAPTER XIV

MEAT AND MEAT PRODUCTS

Flesh foods afford in general more concentrated nourishment than vegetable substances. This concentration which has been made in the animal body, generally by the use of vegetable substances, furnishes a food containing much protein and a small quantity of starch or sugar. The fat of the food which is necessary for the growth and nutrition of the body may come either from the vegetable or animal kingdom, and the balance of the ration can be built up by the use of a variety of foods containing starch and sugar. The legumes and nuts are the only vegetable foods that contain large amounts of nitrogenous material, and they are extremely useful in a mixed diet. (See p. 188.)

ANIMAL FOOD

Animal food may be classified in accordance with its origin into that from (1) mammalia, (2) birds, (3) fish, (4) other sea food, and (5) miscellaneous.

The common animals used for food include such domestic mammals as beef cattle, swine, sheep, goats, horses, camels and reindeer. Of less importance are wild mammals such as the deer, elk, moose, alpaca, llama, guanaco and antelope. Some carnivora, especially the badger, bear and raccoon, are often used for food, and among rodents the rabbit, hare, squirrel, marmot (wood chuck), beaver, hedgehog, porcupine and opossum. The mammalia living in salt water, namely, the porpoise, whale, narwale, walrus and seal, are in some countries utilized as food.

MEAT

The term meat generally includes not only the muscular tissue or lean meat, but all that is purchased, as meat including fat, tendons, skin and bones. As beef is a standard meat, it is convenient to study its properties as typical of the whole class. The amount of fat in meat varies within wide limits, and may be as low as 3 per cent. in beef to 90 per cent. in fat pork. Usually lean meat having from 8 to 12 per cent. of fat distributed through it is considered the most satisfactory. In an emaciated animal as low as 2 per cent of fat is sometimes found in the lean tissue, but in a carcass which is in the condition for a good grade of beef as high as 8 per cent., and in an extremely fat carcass 22 per cent. of fat is found distributed through the lean tissue.

Structure of Meat

Meat is made up of muscle fibers held together by connective tissue;1 the latter is composed largely of lactin and collagen. Each fiber has a sheath or covering and within the fibers are contained the meat juices, which are solutions, in water, of proteins and non-protein nitrogenous extractives. (See p. 20.) The proteins of these juices consist chiefly of the globulin myosin, muscle albumin and hæmoglobin and salts. The muscular tissue is composed almost entirely of nitrogenous material. There are no peptones in the living muscle, but the ferment pepsin is present. After death, by the action of pepsin in the presence of lactic acid, the muscles are partially digested so that both peptones and proteoses are found. The muscle contains not to exceed 1 per cent. of a carbohydrate called glycogen (C6H10Oы), or animal starch, which is formed from the sugars taken into the circulation in the digestive tract. There are two classes of muscular tissue, the voluntary or striated muscles, like those of the leg, and the involuntary or non-striated muscles like those of the heart.

1 Food Inspection and Analysis, Leach, 4th Ed., p 205.

Slaughtering Meat

In discussing the slaughtering of meat, H. W. Wiley says1 "The principal thing to be considered is first a sudden, and in so far as possible, a painless death of the animal; second, the immediate withdrawal of the blood of the slaughtered animal, if slaughtered otherwise than by opening the principal artery; third, the removal of the intestines and hair or hide of the animal; fourth, immediate cooling at a moderately low temperature until the animal heat is entirely radiated; fifth, the cutting of the carcass into the usual form for consumption and the removal and utilization of the débris for food or other purposes; sixth, the delivery of the meat, if to be eaten in a fresh state in a condition secured from contamination and decay until it is in the hands of the consumer; seventh, the curing of the meat in a proper manner by salt, sugar, vinegar and wood smoke, and the delivery thereof in an unadulterated form to the consumer."

In many of the large cities there is upon the market a variety of meat known as "Kosher" meat, which is killed by a "Shohet" or expert meat inspector, under the laws of the Jewish Talmud.

Keeping Meat

After slaughtering, the meat undergoes several changes. Immediately after being killed the flesh, especially in young and well-nourished animals, is juicy and tender. On account of the clotting of the myosin, after a short time rigor mortis ensues and the meat becomes stiff and hard. In the third stage to which the meat soon passes, it becomes again soft and tender, owing in part to the action of lactic acid on the sarcolemma and connective tissue. This process should not, however, be allowed to go too far, or the meat will become "high" and have a disagreeable odor and flavor.

This development of the lactic acid rendering the meat tender, is called "ripening" of the meat. Refrigeration retards this process, hence meats can be kept fresh for a considerable time at a low temperature (below 40° F.). The experiments by P. F. Trowbridge, show that as long as the amount of lactic acid continues 1 Foods and Their Adulteration, Wiley, p. 14. Missouri Agri. Exp. Sta.

to increase the meat appears to be improving in quality. At a certain stage, however, basic bodies begin to separate, which neutralize the lactic acid and thus cause a decrease in the amount of this free acid. The meat is still edible after this decrease has begun, but whenever enough basic bodies are liberated to neutralize all the lactice acid, the meat has then reached a stage of incipient putrefaction and is no longer fit for food.

Game is often allowed to "hang" until the changes of decomposition are well marked and in this condition it is highly relished by epicures.

Chemical Composition

The different cuts of beef differ quite widely in composition, dependent on the location of the "cut," and the quality or grade of beef. This is well illustrated in the following analyses taken from Mo. Ag. Ex. Sta. Bulletin:

The flavor of meat depends on the amount of nitrogenous extractives-the creatin, creatinin, xanthin, etc., present. The amount of these "meat bases" is small-from 4 to 15 grains only per pound in ordinary meats. When these are removed by boiling, the meat is almost without flavor. Only a trace of the nitrogen present is in the albumoses and peptones. It is stated that not far from half of the nitrogen in water-soluble flesh consists of the extractives and half is coagulable proteins.

Cooking Meats

The cooking of meats has been very thoroughly studied.1 Among civilized people meats are usually cooked before they are eaten, because this process improves the taste and makes them more palatable, injurious animal parasites and bacteria are destroyed and finally the tissues are thoroughly softened so that they can be readily attacked by the digestive fluids. In the process of roasting or boiling a moderately large piece of meat, the interior never reaches a temperature above 190-200° F.2 The time required to roast a piece of beef depends on its size, shape, etc., and the temperature of the oven. For example, a single short rib roast containing the bone, required 16.3 minutes per pound to cook the meat rare, while the two-ribbed rolled roasts averaged 20.1 minutes at the same temperature to reach the same conditions. If the roast is quite completely covered with fat, the heat penetrates only through the lean portions exposed.

Roasts are as quickly cooked at an oven temperature of 175° C. (347° F.) as at 195° C. (383° F.), so the higher temperature involves a waste of fuel. There is much less danger of overcooking the meat at the temperature of 100° C. (212° F.), than at a higher temperature, but of course a much longer time is required to raise the temperature of the interior. By slow cooking, however, the interior is in a much more uniform condition.

IU. S. Dept. Agric. Office Exp. Sta. Bul. No. 162.

2 Bul. Univ. Ills. Vol. 55, No. 19; U. S. Dept. Agric. Farmers' Bull. No. 162.