(c) Muscle juice.
Two proteins exist in connective tissue, viz., collagen and elastin. Collagen is changed into gelatine by cooking in water. Elastin is found not only in connective tissue, but in the walls of muscle fibers. In muscle juice, there are two proteins,—myosin or muscle globulin and albumin.
Both myosin and albumin coagulate by heating. It is possible to sear meat because it contains proteins. The scum which invariably forms when meat broth is heated consists largely of protein, probably in the form of albumin. This protein as shown in experiments on eggs is soluble in cold water, but is coagulated by heating. If meat broth is skimmed, much of its nutriment is lost.
[Illustration: Courtesy of Bureau of Publications, Teachers College FIGURE 54—ROUND.]
[Illustration: Courtesy of Bureau of Publications, Teachers College FIGURE 55.—CHUCK.]
Of all proteins in meat, myosin is the most important; it exists in greater quantity than the other proteins. Myosin, is practically insoluble in both hot and cold water, though somewhat soluble in a salt solution. As not much myosin is extracted from meat in soup making, the solid part of meat must be eaten in order to obtain the greatest nourishment. Meat broth does not contain as much food value as meat.
CHOPPED BEEF.—If meat is chopped, what is the effect of the cutting on its structure? How would this affect its toughness?
It is possible to pan-broil or roast some of the tough cuts of meat, if the meat is chopped fine. Round (see Figure 54, p. 203) and shoulder or chuck (see Figure 55) are especially desirable cuts for this purpose.
CHOPPED STEAK
1 pound beef steak, chopped 1 to 2 tablespoonfuls chopped parsley 1 onion, grated 1 teaspoonful salt 1/2 cupful water or 3/4 cupful tomatoes 1/8 teaspoonful pepper