Meats are derived from the flesh of domestic and wild animals chiefly if not exclusively of herbivorous habits, and from fowls. The most important kinds are beef (ox), veal (calf), mutton (sheep), lamb (young sheep), pork (pig), ham and bacon (pig), venison (deer). Poultry includes chickens, turkeys, ducks and geese, guinea hens, and game birds.

The quality of meat is dependent on the condition of the animal from which it is derived. Of all the foods, meat is the one most subject to conditions rendering it unwholesome or even dangerous. Certain diseases of animals are communicable to man through eating of the flesh, and there is danger that through lack of cleanliness in slaughterhouses and exposure to dust and flies, meat may be infected with Bacillus enteritidis which produces poisonous products which are not destroyed by cooking and which are now considered to be the commonest cause of food poisoning - so-called "ptomaine" poisoning.

The United States Department of Agriculture, under the meat inspection law of 1906, provides for the inspection of establishments which send products into foreign or interstate commerce. There are, however, many establishments which do business entirely within one state and they may or may not have local inspection. For the need of state inspection see United States Department of Agriculture, Bureau of Animal Industry, Circular 154 (1908).

In meat as it is purchased we have bone, fat, and the flesh, consisting of the muscle of the animal with its connective tissue.

The color of the meat should be clear and bright, not purplish. There should be very little odor, and the meat should be firm and elastic to the touch.

Meat is valuable chiefly for its protein, fat, and ash constituents. The protoplasm of the muscle cells consists mainly of proteins partially dissolved in 3 to 4 times their weight of water. The fat is deposited partly in the cells and partly in the connective tissue between the cells, where it forms in layers. Fat does not alter the composition of the actual protoplasm since it neither dissolves in nor absorbs water. When an animal is killed, the muscular protoplasm coagulates (rigor mortis), but without essential change in the amount or distribution of moisture, protein, or fat. Muscle protein and gelatin differ conspicuously in their content of amino acids. It is now known that the inadequacy of gelatin alone as protein food is due to the absence of certain amino-acid radicles, particularly tryptophan and tyrosin. Special interest attaches to the "extractives" of meat, to which its flavor is largely due, and to the purins which give rise to uric acid in the body. Among the extractives creatin is most conspicuous. The purins exist "free" (as in the form of hypoxanthin, adenin, guanin) and "bound" as constituents of the nucleoproteins.

Cold storage, drying, canning, and the application of preservative substances are the principal means of preserving meats. Salt, sugar, vinegar, and wood smoke are condimental as well as preservative in their properties, and there is no restriction upon their use. Saltpeter maintains the red color of meat and preserves it. Boric acid and borax, which when used are employed purely for their preservative effect, and sulphites are not permitted under the present United States meat inspection law.

For fuller discussion of composition, nutritive value, preservation and inspection of meat, read Sherman's Food Products, Chapters VI and VII.