As raw meat is found to be more digestible than cooked, the cooking of meat is clearly for other purposes. This also suggests that the rarer cooked meat is, probably the more digestible. For tender meats experiment confirms this expectation. Cooked meat is, however, generally more palatable than uncooked. As 95% of it is digested when cooked, cooking is considered advisable. Cooking develops flavor; it also destroys bacteria and any other parasites present. Overcooking is to be avoided, as this hardens fiber, making it indigestible.

In vegetables, cellulose was found so to incase the nutrients as to need to be broken up in order to release these. In meats, connective tissue holds together the muscle fibers; in it are embedded the fat particles. As cellulose was loosened and softened by heat, so connective tissue by means of heat loosens its hold upon the muscle fibers and the fat. The connective tissue itself becomes gelatin. (See pp. 94 and 98).

In young animals connective tissue is delicate and the muscle fibers short and tender. With age, exercise, exposure, both muscle fiber and connective tissue toughen and harden. They then require more prolonged cooking. When tender, heat acts quickly upon them.

Tender meat is subjected to high temperature for a short time. Tough meat requires low temperature and prolonged cooking. Why?

To retain nutrients in meat, dry heat is used. Large, thick cuts of meat are seared (juices and fat brown together quickly on outside). When the inside is thus incased it really cooks in the water of its own composition, rather than by dry heat as did the outside. The albumen that has coagulated on the outside prevents the further escape of the meat-juices. It is such cooking that makes meat most nutritious, unless it is very tough. Steaks are so cooked.

Effects. Cooking Of Meat

All meats as cooked lose some weight. This loss is, however, principally water. This is caused by the hardening of fiber forcing out the water. (Fresh meat does not shrink as much as unsound, for meat as it undergoes decomposition grows liquid.) By boiling, about 1/2 the weight is lost. Of this less than 5% is of nutrients. By dry heat about 1/3 is lost as water, while the loss in protein is very slight. Yet more of the nutrients actually become soluble by dry heat than during boiling. But these are not lost if gravies and sauces are made with the juices and drippings. Cooked meat is as a whole somewhat less soluble than uncooked. In so far as it is, it is decreased in nutriment, for food, to be used by the body, must be soluble in its digestive juices.

Meat-juices obtained by pressing heated round steak are nearly 12% protein and extractives. The extractives are one half as much as the protein. But since no method of cooking brings out the nutrients to any great degree, they are mostly in the meat, even stew- and soup-meat. This should therefore be considered a food of value, though it needs to be so prepared as to increase its palatability. Meat-powder is for this reason more nutritious than meat extracts.

To extract nutrients meat is cut fine, soaked in cold water, and cooked at low temperature. Near the end of this process the temperature is raised to the boiling point for a short time to dissolve the connective tissue. High temperature hardens muscle fibers but is needed to dissolve connective tissue. Stews and soups are so made. (In retaining nutrients after searing, the temperature is lowered to prevent hardening of the fibers).

(See p. 98).

Building, sparing, stimulating effects are produced by meat foods.