Eggs
Eggs.—The table shows eggs to have a chemical composition of water 73.7%, protein 14.8%, fat 10.5%, and mineral salts (ash) 1.0%. Fuel value per pound, 672 calories. The white of the egg, constituting 57% of the entire weight, is composed chiefly of albumen and water with a small percentage of mineral salts in the form of calcium, potassium, magnesium, sodium, phosphorus, chlorin, sulphur, and iron. Typical albumens are always rich in sulphur, and in eggs the sulphur content is much greater in the egg white than it is in the yolk. The yolk of eggs contains more protein and fat than the white, and less water. The protein of the yolk is chiefly in the form of ovovitellin, while the fats occur as palmitin, olein, and stearin. There is also 5% of coloring matter in the yolk of eggs besides lecithin, nuclein, salts of iron, potassium, magnesium, and phosphorus. The latter mineral salt comprises 1.0% in yolk, while in the white there is only .03%. Eggs have a position in the invalid dietary second only to that of milk. They are nutritious, easy of digestion, and exceedingly palatable if properly selected and correctly prepared. The albumen in the white is very susceptible to the effect of heat. At a temperature of about 135° F. the clear, pale yellowish white begins to change to an opalescent tint, and, as the temperature is gradually increased, the texture changes from a viscid, sticky substance to an opaque, jelly-like mass which solidifies with an ever increasing temperature. Hard cooked white of egg, unless it is very finely divided, is considered difficult of digestion, but if the heat is applied gradually and is not raised to the boiling point (212° F.) there is no reason why the hard cooked white of the egg should not be digested. However, it is unwise to cook eggs in this manner for invalids or children. Any of the other methods, with the exception of frying, which should never be used, is decidedly preferable. Egg albumen is soluble in water and fresh fruit juices, so that it may be used with great success as a reinforcing agent. In fact, the whole egg may be so used, but it is more difficult to disguise the yolk in a beverage than it is the white, and for this reason it is not so adaptable in many cases. Eggs may be cooked by the following methods in the invalid dietary: coddled, soft-cooked, poached, creamed, omelet, scrambled, or in custard. Uncooked eggs may be given in water, milk, wine, or fruit juices.
The selection of eggs is equally as important as the selection of other foods. There are “new-laid eggs,” “fresh eggs,” and just “eggs.” The latter are generally storage and should not be used for the sick or for infants. As a rule old eggs will not stand poaching, the whites and yolks mingle and form an unappetizing mass. It does not make any difference whether the color of the shell is white or brown; if the egg is absolutely fresh the white and yolk should be distinct and easily separated, and when they are not it is safer to discard the egg entirely.