This section is from the book "Mrs. Rorer's Vegetable Cookery And Meat Substitutes", by Sarah Tyson Rorer. Also available from Amazon: Mrs. Rorer's Vegetable Cookery And Meat Substitutes.......
(Solanum tuberosum, Linn.)
Potatoes, when carefully cooked, constitute a wholesome, easily digested, starchy food. They cannot be depended upon in any way as a complete food, but act as a diluent to such nitrogenous foods as nuts, peas, beans and lentils. The food value and digestibility depends upon the method of cooking. Baked or boiled, carefully, they are more easily digested than white bread or hominy. When fried or mashed and patted down with melted butter they are less digestible. In frying, the outside crust is hardened in the hot fat, which hinders the digestion secretion of the mouth from acting upon the starch grains.
Potatoes belong to the carbohydrates, or heat, fat and energy producing foods. They are digested in the mouth and small intestine. Unless well masticated the small intestine must do the work alone.
The flavor of the potato is due to a mineral matter. The starchy or nutritious part of the potato lies near the skin; hence the necessity of a thin paring.
Full-grown potatoes are best. Very young and very old potatoes are sometimes not worth the cooking. The potato is a swollen underground stem, the storehouse for the nourishment of the young plant; hence, in the spring when the potato sprouts it does so at the expense of the starch; the skin becomes loose; the flesh of the potato shrinks, and a large part of the nourishment is lost. Old potatoes should be carefully peeled and soaked in cold water at least thirty minutes before cooking.