As eggs are laid the shell is almost full of material. The egg-contents do not thicken for nearly twelve hours. It is better even to delay their use for twenty-four hours longer. Only eggs that are newly laid or kept fresh are fit for human food.

Eggs are used not only as an article of diet, that is, a food at a meal, but also largely as a food-ingredient, as in flour- and other food-mixtures. They add nourishment and lightness. Compare composition of eggs, chicken, veal, fish, milk (p. 103). By what should eggs be supplemented ? Choose specific foods from table on p. 192. What foods can eggs be substituted for ?

Cooking of eggs is important, as it affects their digestibility. Eggs, like meat, lose water when cooked; otherwise they do not change in composition, but the albumen coagulates. The protein and fat of egg are usually entirely assimilated. Egg-yolk cooked either soft or hard is equally digestible with uncooked. Egg-white uncooked is more digestible than cooked.

Digestibility Of Cooked Eggs

Eggs cooked at 212° F. for 3 min., after 5 hr., 8+ % undigested.

Eggs " " 2120 F. " 5 min., " 5 hr., 4- % undigested.

Eggs " " 2120 F. " 20 min., " 5 hr., 4+ % undigested.

Eggs " " 1800 F. " 5 - 10 min., " 5 hr., fully digested.

(Results in a government food-experiment) Note time - temperature - result.

Hard-boiled eggs require thorough mastication.

For adults in health eggs are a wholesome repair food. Though the yolk gives seven times the heat-energy of the white, eggs need to be combined with energy foods. If eaten with bread or on toast, what they lack is added. For children and invalids they give, besides salts, a most digestible protein that builds advantageously for growth and recuperative repair.