They contain from 70-90 per cent water, 8-26 per cent carbohydrate in the form-of starch, sugar, pectin, and cellulose, t per cent mineral matter, less than 2 per cent protein, and only a trace of fat. When we purchase them at the market they contain about 20 per cent refuse. That is, about 20 per cent is trimmed off when we prepare them for cooking. Roots and tubers are cheap foods and supply almost - endless variety to the diet, since they are easily prepared in many appetizing ways. They furnish 16 per cent of the average American diet, potatoes alone furnishing 12% per cent. Their food value is in the carbohydrates and mineral salts which they contain. Roots and tubers are usually grouped into two classes, — starchy roots and tubers, which include potatoes, sweet potatoes, yams, and the starchy foods prepared from roots and stems, as tapioca, sago, and arrowroot; and succu- 73 74 ROOTS AND TUBERS lent roots and tubers, which include beets, turnips, carrots, rutabagas, parsnips, salsify, celeriac, radishes, onions, kohl- rabi, and garlic. The flavor and odor of these foods are due to the presence of volatile oil which may be retained or dissipated by proper cooking. Typical Root or Tuber, Potato. COMPOSITION, — 78,3. Deby. cent) water: ost percent carbohydrate, of which 16 per cent is starch, 2 per cent dextrin; Sugar, pectose,4.4\ per cent cellulose: 3322 perecen: nitrogenous matter, of which 1.3 per cent is protein; I per cent mineral matter. STRUCTURE. — The potato consists of a network of cells held together by cellulose and surrounded by a brown corky skin. The cells contain starch, mineral matter, and a very small amount of protein. Experiments with Potato to show Content. Water. — Let the potato stand in a warm, dry place and weigh it occasionally. Note the loss of water by evaporation. Starch. — Grate the potato, place in a cheesecloth bag, and wash the starch out. Let the water stand until the starch settles, then pour the water off and weigh the starch. Starch test: A solution of iodine turns starch blue. Ash. — Burn potato in a crucible until nothing remains but the ash. Foop VALUE. — Potatoes are the most important car- bohydrate food, and it may be said that they are served at every dinner and usually at one other meal in the aver- age American home. They generally furnish the main carbohydrate part of a dinner and are valuable also for the potash and other important mineral salts which they contain. ROOTS AND TUBERS 75 PRINCIPLES INVOLVED IN COooKING. — Potatoes are made up of innumerable cells, having walls of cellulose and inclosing starch, mineral matter, water, and a small amount of protein. Heat causes the starch grains to swell and burst the cell walls, and thus the starch is free so that the digestive juices can act on it. Heat coagulates the protein. Some starch and mineral matter are lost when potatoes are pared and cooked in boil- ing water. ‘There is no loss when they are steamed or baked. | METHOD OF PREPARATION. — Potatoes should be pared thin, as much of the protein and mineral salts are directly under the skin and are lost in deep paring. When potatoes are being prepared, they should be covered with water and should remain in water until it is time to cook them. If they are exposed to the air, they turn black, because certain ferments in them become active in the presence of oxygen. Old potatoes may be soaked in water to restore some of the lost moisture, but ordinarily nutrients are lost if potatoes are left soaking in water for any length of time. Potatoes should always be cooked in boiling water, not simmering or nearly boiling, so as to coagulate the protein and retain all the nutrients possible. MetHops OF CookING. — Baking, boiling, scalloping, Hrving eter Grated potatoes are used for puddings, pies, muffins, soups, cakes, etc. Baked Potatoes. — (See recipe, page 35.)

AI-modernized reading of the original text

They contain from 70-90 per cent water, 8-26 per cent carbohydrate in the form-of starch, sugar, pectin, and cellulose, t per cent mineral matter, less than 2 per cent protein, and only a trace of fat. When we purchase them at the market they contain about 20 per cent refuse. That is, about 20 per cent is trimmed off when we prepare them for cooking. Roots and tubers are cheap foods and supply almost - endless variety to the diet, since they are easily prepared in many appetizing ways. They furnish 16 per cent of the average American diet, potatoes alone furnishing 12% per cent. Their food value is in the carbohydrates and mineral salts which they contain. Roots and tubers are usually grouped into two classes, — starchy roots and tubers, which include potatoes, sweet potatoes, yams, and the starchy foods prepared from roots and stems, as tapioca, sago, and arrowroot; and succu- lent roots and tubers, which include beets, turnips, carrots, rutabagas, parsnips, salsify, celeriac, radishes, onions, kohlrabi, and garlic. The flavor and odor of these foods are due to the presence of volatile oil which may be retained or dissipated by proper cooking. Typical Root or Tuber, Potato. COMPOSITION. — 78.3 per cent water; 16.5 per cent carbohydrate, of which 16 per cent is starch, 2 per cent dextrin; sugar, pectose; 1.4 per cent cellulose; 2.2 per cent nitrogenous matter, of which 1.3 per cent is protein; 1 per cent mineral matter. STRUCTURE. — The potato consists of a network of cells held together by cellulose and surrounded by a brown corky skin. The cells contain starch, mineral matter, and a very small amount of protein. Experiments with Potato to show Content. Water. — Let the potato stand in a warm, dry place and weigh it occasionally. Note the loss of water by evaporation. Starch. — Grate the potato, place in a cheesecloth bag, and wash the starch out. Let the water stand until the starch settles, then pour the water off and weigh the starch. Starch test: A solution of iodine turns starch blue. Ash. — Burn potato in a crucible until nothing remains but the ash. Foop VALUE. — Potatoes are the most important carbohydrate food, and it may be said that they are served at every dinner and usually at one other meal in the average American home. They generally furnish the main carbohydrate part of a dinner and are valuable also for the potash and other important mineral salts which they contain. PRINCIPLES INVOLVED IN COOKING. — Potatoes are made up of innumerable cells, having walls of cellulose and inclosing starch, mineral matter, water, and a small amount of protein. Heat causes the starch grains to swell and burst the cell walls, and thus the starch is free so that the digestive juices can act on it. Heat coagulates the protein. Some starch and mineral matter are lost when potatoes are pared and cooked in boiling water. ‘There is no loss when they are steamed or baked. | METHOD OF PREPARATION. — Potatoes should be pared thin, as much of the protein and mineral salts are directly under the skin and are lost in deep paring. When potatoes are being prepared, they should be covered with water and should remain in water until it is time to cook them. If they are exposed to the air, they turn black, because certain ferments in them become active in the presence of oxygen. Old potatoes may be soaked in water to restore some of the lost moisture, but ordinarily nutrients are lost if potatoes are left soaking in water for any length of time. Potatoes should always be cooked in boiling water, not simmering or nearly boiling, so as to coagulate the protein and retain all the nutrients possible. METHODS OF COOKING. — Baking, boiling, scalloping, frying, etc. Grated potatoes are used for puddings, pies, muffins, soups, cakes, etc. Baked Potatoes. — (See recipe, page 35.)

Principles of cooking