becomes heated. White, or Irish, potatoes roasted with their skins on best retain their flavor as well as valuable mineral salts (potash, etc.).
Cooking by hot air can only be used with moist foods. Baking is an example. Foods only slightly moist are made hard, dry, and unpalatable if cooked by this method.
Cooking by Boiling.—To boil potatoes so as to make them mealy instead of soggy, the water should be boiling when they are put in, and after they are cooked the water should be poured off and the pot set on the back of the stove for the potatoes to dry. Boiling onions drives off the acrid, irritating oil. Rapid boiling of vegetables gives less time for the water to dissolve out the nutrients. (See Steaming.) Raw cabbage is treated by the stomach as a foreign substance, and sent promptly to the intestine; cabbage boiled with fat may remain in the stomach for five hours. Instead, it should be boiled in clear water for twenty minutes. Beans and peas require several hours' boiling.
Cooking in hot liquid below the boiling point is better than boiling. In frying meat, it should be put in hot grease that a crust may be formed to prevent the grease from soaking in. Grease much above boiling point becomes decomposed into fatty acids and other indigestible products. Hence butter is more digestible than cooked fats. In whatever way meat is cooked, it should never be salted until the cooking is finished or the salt will draw out the juices which flavor it. Eggs may be cooked by placing them in boiling water and setting the kettle off the stove at once to cool. A finely minced hard-boiled egg is as digestible as a soft-boiled egg. Since boiling for more than a very few minutes coagulates and hardens albumin, there is no such thing as boiling meat without making it tough and leathery throughout. It may be stewed, a process which belongs to the next method.
In stewing meat, it may be plunged into boiling water for a few minutes; this coagulates the albumin on the surface. The fire should then be reduced, or the vessel set on the cooler part of the stove, or a metal plate should be placed beneath it, that the water may barely simmer. The water should show a temperature of 185° or 190° if tested with a thermometer. A piece of meat cooked in this way is tender and juicy.
Cooking by steam requires a double vessel or a vessel with a perforated second bottom above the water, through which the steam may rise to the food that is to be steamed. Steamed vegetables have a better flavor and are more nutritious than those cooked in any other way. A steamer is different from a double boiler. Oatmeal should be cooked for at least forty minutes, and it is more digestible if steamed for several hours until it is a jelly. To do this, it may be cooked during the preparation of two meals. Cooking that leaves it lumpy and sticky is a disadvantage, and makes it more likely to ferment than if eaten raw.
