CHAPTER III. ANIMAL FOODS: MEAT, FISH, EGGS, ETC. MEAT The universal consumption of meat as a daily article of diet by civilized man is of more recent origin than is generally supposed. McCulloch states that "so late as 1763 the slaughter of bullocks for the supply of the public markets was a thing wholly unknown, even in Glasgow, though the city then had a population of 30,000." In the past decade or two the consumption of meat has increased enormously, especially in the United States and England, owing to the development of cheap refrigerator processes, canning, and increased facilities of transportation. The annual per capita consumption of meat has almost doubled during the past half century. It is estimated in pounds as follows: Structure and Composition of Meats.-Meat is composed of muscular fibers, and the structures intimately associated with them, such as connective tissue, blood vessels, nerves, lymphatic vessels, and more or less adipose tissue. The toughness of meat is due to the thickness of the walls of the muscle tubes and excess of connective tissue which binds them together. hence the flesh of young domesticated animals is usually more tender than that of old or wild animals. The flavor of meat varies with the animal's age, its food, breed, and condition when killed. The meat of male animals, excepting pigs, is usually more highly flavored than that of females. Meat contains albuminoids and gelatinoids; the latter through ac "Statistical Account of the British Empire," Vol. II, p. 502. tion of hot water or steam are converted into gelatin. In addition meat contains the following nitrogenous substances: syntonin, myosin, muscle albumin, serum albumin, and numerous extractives, such as creatin, creatinin, xanthin, hypoxanthin, lactic acid; and small quantities of inosit and glycogen. Meat at once after slaughter has an alkaline reaction, is tough, and possesses a sweetish and rather unpleasant flavor. Rigor mortis soon sets in, accompanied by the following changes: the reaction of the meat turns acid, owing to the development of sarcolactic acid; the connective tissue and fibers are softened as the result of autolytic enzymes and also as a result of bacterial action. While the meat becomes more tender, it also develops pleasant flavors. It is, therefore, not advisable to use meat at once after slaughter, but it should be allowed to hang at least two or three days. It is important during this time to preserve the meat from contamination with pathogenic microorganisms and to retard the growth of the saprophytes. Nutritive Value of Meat.-The nutritive value of meat depends mainly upon the presence of proteins and fats. Nitrogenous extractive. matters, such as creatin, xanthin, etc., sometimes called meat bases, are formed by cleavage of the proteins, but are of little value as foods. These nitrogenous extractives are present in about the same amount in both red and white meats, with the single exception of venison, which contains the least amount. Meat must be regarded as a condensed and expensive food. For instance, a steak that costs twenty-five cents a pound contains over one-third or one-half of inedible substances, so that the edible portion really costs double that amount. On the contrary, when a pound of flour or cereal is purchased, the price of which is perhaps only oneeighth that of meat, the whole of it is edible. Beef extracts are nothing more or less than a soup or soup stock specially prepared from beef. They first became generally known through the researches of Liebig, and are now an important article in commerce. The composition of the ordinary beef extract of commerce contains from 15 to 20 per cent. of moisture, from 17 to 23 per cent. ash, and from 50 to 60 per cent. of meat bases. These meat bases are the soluble nitrogenous contents of meat. They contain only a trace of soluble albumin, albumoses, and peptone. The chief meat bases which form the principal part of the substance are creatin, creatinin, xanthin, carnin, and carnic acid. It is, therefore, evident that meat extracts contain little nutritive matter, although this, being in a state of solution, is probably more readily absorbed than a similar amount of other nutritives in the form of ordinary meat. Wiley properly points out that the claim made by manufacturers is misleading, in that one pound of extract contains the nutritive properties of many pounds of meat. Such a statement is absurd upon its face, and should not be allowed to go unchallenged. These extracts may be useful as stimulants or as condiments, or as a means of speedily introducing a soluble nutrient in the case of disease, where it is extremely important that even small amounts of nutritious material should enter the body. A distinction should be made between beef extract and beef juice. Beef juice is obtained by strong pressure and is concentrated in vacuo to the proper consistence, or it may be used freshly prepared in the household. Sources of Meat. The principal source of meat is from cattle, sheep, and swine. In many places the flesh of horses, dogs, and cats is eaten. In Germany horses and dogs are slaughtered and regularly inspected for human food. The meat of these animals is also used in other countries that have long been flesh hungry. There is no sanitary objection to the use of such meat. Horse meat, when eaten in ignorance of its true character, makes no unpleasant impression. In Paris, Vienna, and other cities large quantities of horses, mules, and donkeys are slaughtered for food. Even in the United States several thousand horses are slaughtered and officially inspected each year with other food animals. It was formerly difficult to distinguish horse meat, but this is now rendered comparatively easy by means of the specific precipitins. (For this test see page 400.) The different kinds of meat may be detected by physical, microscopical, chemical, or biological tests. Ordinarily meats from different animals may be distinguished by their odor or taste. Microscopically the fibers resemble each other so closely that this test is not to be relied upon. Meat varies somewhat in chemical composition from different species, from different animals of the same species, and even from different muscles in the same animal. The principal difference in the chemical composition of meats from animals of different species consists in the glycogen and fat content. Thus, horse meat contains considerably more glycogen than beef. The glycogen test, however, is not reliable because it may be changed as a result of bacterial action. The fats of different animals have different physical and chemical characteristics. The fats crystallize in different forms and have different melting points; also the fatty acids derived therefrom. A careful examination of the fat, therefore, will lead to an approximate degree of knowledge concerning the character of the flesh from which it has been derived. For instance, lard and beef fat are easily distinguished from each other. The Recognition of Spoiled Meat.-The recognition of spoiled meat that is also injurious to health is a very difficult task. Meat that is decomposed, putrid, or offensive, and thus objectionable to the senses, needs no further condemnation. The most serious infections and pois ons in meat, however, do not, as a rule, affect its appearance, odor, or taste, or do so so slightly as readily to pass unnoticed. Certain putrefactive changes brought about by bacterial action, which give the high or gamy taste so much prized by epicures, appear not to be injurious. Dogs and other carnivora prefer putrid flesh. Meat inspectors are usually instructed to condemn meat that has not a red, fresh appearance, especially if it has become brownish or greenish. The meat is to be condemned if, upon pressure, much fluid of abnormal color or alkaline reaction exudes; if the fat is not yellow and firm, especially if soft and gelatinous; if the marrow of the femur is not firm and rose-colored and has become soft and brownish. Spoiled meat under the microscope shows obscurity of the cross striations of the muscle fibers and numerous bacteria. For a further discussion of this subject see Meat Inspection, and also the various diseases which render meat unsuitable or injurious as food. Prevention. The prevention of infections and poisoning from meat and meat products depends, first of all, upon the health of the animal, next upon the mode of death, and finally the methods of butchering, preserving, and handling the flesh. Careful attention to every detail is necessary all along the line. Cleanliness approaching surgical methods on the part of the butcher during the preservation, transportation, and preparation of the meat is called for. A careful system of meat inspection is a good sanitary safeguard. Thorough cooking is the most important protection we have against infection. Meat should never be eaten raw, even where there is a carefully conducted inspection by trained experts. Individual cysticerci (tapeworm larvæ) are very easily overlooked, and one is enough to bring forth a tapeworm. It is also not possible to examine all hogs, particularly those slaughtered in country districts, for trichina, and even where this is done with care the method does not afford complete protection. It should further be remembered that some of the more serious bacterial infections do not alter the color, taste, or appearance of the meat in any way. Raw meat does not have a higher nutritive value than cooked meat, and is no more easily digested. tion. Special measures of prevention will be discussed under each infec Meat Preservatives.-The regulations of the U. S. Department of Agriculture permit the addition to meat or meat food products of the following substances: common salt, sugar, wood smoke, vinegar, pure spices, saltpeter, benzoate of soda. Only such coloring matters as may be designated by the Secretary of Agriculture may be used. The adulterants most commonly used in meats are saltpeter, boracic acid, borax, sulphite of soda, and benzoic acid. MEAT INSPECTION The necessity for a careful sanitary control of our food is growing greater year by year in order to protect the consumer. This is especially necessary in the case of animal food products, especially meat and milk, which are most apt to carry infections and are the most readily decomposable. The necessity for this inspection is accentuated by the fact that the producer and the consumer are often separated by great distances, and, further, there are several middlemen between the two. The ignorance or greed of the middleman or the producer may force upon the consumer meat that is injurious or that is considerably below value. The danger does not consist alone in eating infected or decayed animal products; the mere handling of flesh of some animals having had anthrax or glanders may be sufficient to transmit infection to the butcher or housewife, who may injure themselves in cutting the meat. An efficient meat inspection system is not only of advantage to man, but is the means of detecting and preventing disease among cattle, sheep, and swine. A sharp outlook at the slaughter house will discover the first appearance of rinderpest, foot-and-mouth. disease, Texas fever, or other epizootic, which may then be quickly traced to its origin and nipped in the bud. The border line between health and disease is ill-defined. It is doubtful whether any animal slaughtered for food is wholly sound and free from disease. Parasitic infections among the lower animals are exceedingly common. Anyone may convince himself of this fact by a visit to a slaughter house, for there he will see that many hogs have a handful of round worms in the intestinal tract; most animals have one or more species of intestinal worms, such as hookworms, tapeworms, and many protozoa, but, fortunately, these are for the most part not dangerous to man. Almost every hog or beef that is killed contains a sarcosporidia, a small parasite that inhabits only the muscles of these animals and which is harmless to man. It is, therefore, at once evident that the line in meat inspection cannot be drawn between health and disease, but aims to eliminate those diseases which are injurious to man and those diseases and conditions which render the meat of inferior quality or otherwise unfit for use. In establishing correct principles to guide a meat inspection service sentiment must give way to science. The killing of animals and the dressing of the carcasses is not a kid-glove business. In our country much good meat is condemned and destroyed according to law as a result of supersensitiveness. When meat becomes scarcer and prices higher this waste will be checked by a closer adherence to a sound |