STARCH is a very important FUEL food; like sugar, it gives energy to the body. Starch is closely related to sugar; it has much the same composition and the same use in the body. In certain respects, however, starch differs from sugar.

EXPERIMENT 14: THE STARCH TEST.—Put a drop of tincture of iodine on,— corn-starch, flour, rice, cream of wheat, wheatena, oatmeal, tapioca, potato, meat, and egg. What is the result?

If a substance contains starch, it changes to a blue color when tincture of iodine is added to it.

From these experiments determine in which class—animal or vegetable—the starchy foods belong.

EXPERIMENT 15: THE EFFECT OF COLD WATER ON STARCH.—Mix half a teaspoonful of corn-starch or flour with cold water in a test tube or glass cup. What happens to a solid substance when it is dissolved? (See Experiment 6.) Set the mixture aside for a few minutes, then note its appearance. Is starch soluble in cold water? What important difference between starch and sugar does this experiment show?

EXPERIMENT 16: THE EFFECT OF HEAT ON STARCH.—Hold to the light the starch and water mixture from Experiment 15. Is it opaque or transparent? Turn the mixture into a saucepan, heat, and stir it; return the mixture to the test tube or cup and again hold it to the light. What change was caused by heating it? Set the mixture aside for a few minutes. Have the starch and water separated as in the uncooked starch? Can you say it is insoluble, like uncooked starch? Can you say it is soluble, like sugar? What term indicating a half-dissolved condition can you apply to the cooked starch?

EXPERIMENT 17: STIFFENING OF COOKED STARCH.—Place the test tube containing cooked starch from Experiment 16 in cold water. After ten minutes examine it. Can you pour it out of the tube? How does cooked starch change when cooled?

EXPERIMENT 18: THE STRUCTURE OF STARCH.—Examine starch under the microscope. While you are still looking through the microscope, make a drawing of several grains of starch. Insert this drawing in your notebook.

CELLULOSE.—Cellulose is a tough substance found in the fiber of wood. As previously mentioned the outside covering of vegetables and fruits and their interior framework contain much cellulose. The fibrous material found in rolled oats consists almost entirely of cellulose.

EXPERIMENT 19: SEPARATION OF CELLULOSE AND STARCH.—Place a heaping teaspoonful of rolled oats in a cup and add just enough water to cover it. Allow it to stand for at least 15 minutes. Pour the mixture into a cheese- cloth and press out the moisture and much of the starch, catching it in a saucepan. Rinse the starch out of the cloth as thoroughly as possible by holding it under running water. Examine the substance remaining in the cloth. Tear it into pieces. Is it tough? Does it suggest any common material? What is it? Heat the contents of the saucepan. What is this substance?

The tiny grains of starch shown under the microscope (see Figure 23) contain both starch and cellulose. The latter forms the outer covering of the microscopic grains. Starchy vegetables contain much cellulose: (a) in the outside covering; (b) in the interior framework; (c) in the covering of the starch grains.

[Illustration: From Household Chemistry, by J. M. Blanchard. Figure 23.—Grains of Starch. a, potato starch; b, corn-starch. (Much magnified.)]

Some plants rich in cellulose can be eaten in the raw state. But certain fibrous foods, especially cereals or grains, are irritating if eaten in the uncooked condition. It is necessary to soften them if used as food. Now cellulose itself is not soluble in cold or hot water nor is it softened by boiling in water. But other materials existing with cellulose are softened or changed by cooking. Hence changes in these substances in contact with the cellulose brought about by boiling water soften the food and separate cellulose fibers.

Heat and moisture applied to starchy foods serve three important purposes:

(a) They soften the food; (b) they change the starch to a paste or make it semisoluble; (c) they improve the flavor.

Cellulose is not a fuel material; it does not serve in the body as an energy-giver. Its value in diet is due to the fact that it is bulky and furnishes ballast for the alimentary canal. It stimulates the flow of the digestive juices as it brushes against the walls of the digestive tract, and thus aids in the digestion of foods and in the elimination of waste material.

CARBOHYDRATE, A FOODSTUFF.—Because sugar, starch, and cellulose have somewhat the same composition and some properties in common, they are grouped into one class, viz. carbohydrate. Sugar, starch, and cellulose are all included in the term carbohydrate. Carbohydrate is one of the foodstuffs. Sugar is a food containing only the carbohydrate foodstuff. Cereals contain not only carbohydrates but other foodstuffs. They contain, however, a larger quantity of carbohydrate than any of the other foodstuffs, for which reason they are classed as carbohydrate-rich foods.

CEREALS.—Cereals are cultivated grasses, the seeds of which are used for food. The most important are wheat, Indian corn or maize, rice, oats, rye, and barley. From these many different kinds of flours, meals, and breakfast foods are prepared.

Cereals rank high in nutritive value. Many of them contain about 75 per cent of starch. They also contain ash and a substance which builds the body. Because they are widely distributed in various climates, they have an important place in man's diet.

At market one finds two classes of cereals sold as breakfast foods—(1) the ready to eat and (2) the uncooked or partially cooked grains. The ready-to-eat cereals cost much more per pound than the cereals that require cooking. The difference in the price per pound, however, is not an accurate difference in the cost of the two, for the cost of the fuel in cooking grains at home must be taken into consideration.

Of the cereals that require cooking, those that are partially cooked are doubtless the more popular. Many of these such as rolled oats or wheat are steamed and rolled. Hence they take much less time to prepare in the home kitchen than the uncooked grains.

All breakfast cereals require long cooking to make them most palatable, the time of cooking depending upon the character of the cellulose and the method of preparing the cereal for market.

Most partially cooked grains are improved by a longer cooking than is usually given them. It is interesting to measure equal quantities of a rolled cereal and cook one quantity for 20 minutes and the other for 1 1/2 hours and taste each. The superior flavor and texture of the well-cooked cereal is well worth the additional length of time of cocking. Grains are also found on sale in bulk and in package. The latter cost more but insure greater cleanliness. Since, however, cereals sold in bulk are those that require cooking, they will be thoroughly sterilized before serving and need occasion no concern regarding their cleanliness.

GENERAL RULES FOR COOKING CEREALS.—Pour the cereal slowly into boiling salted water. Cook directly over the flame for about 10 minutes. Then place over boiling water and cook from 1/2 to 8 hours. Usually one teaspoonful of salt is used for each cupful of cereal. The quantity of water depends upon the kind of cereal. The double boiler is particularly good for cooking cereals. The fireless cooker also is a most satisfactory device for cooking these foods easily and economically.

Starchy foods are most easily digested when well masticated. Dry foods require more mastication than moist foods. It is well then to have the water used in cooking the cereal entirely absorbed. If, when nearly done, the cereal is too moist, uncover the vessel and cook until the excess of water is evaporated.

Care should be taken, however, not to allow a tough skin to form on the top of the cereal. This digests with difficulty. Its formation can be prevented by keeping the cereal covered or by stirring occasionally.

Heat ready-to-eat cereals in the oven until they are crisp.

ROLLED OATS OR WHEAT

3 cupfuls boiling water 1 cupful cereal 1 teaspoonful salt

Prepare according to the general directions, cooking in the double boiler at least 1 1/2 hours.

CREAM OF WHEAT OR WHEATENA

3 cupfuls boiling water 1/2 cupful cereal 1 teaspoonful salt

Prepare according to the general rule, cooking in the double boiler at least 1/2 hour.

A few minutes before taking from the fire, 1/2 pound of dates, cleaned, stoned, and cut into pieces, may be added. Raisins or figs may also be used with Cream of Wheat and other cereals.

QUESTIONS

How would the temperature of boiling water be affected if a cupful of cereal were poured into it all at once? From this explain why cereals should be added slowly to the boiling water.

Compare the cooked and uncooked cereal. How does it change in appearance and quantity?

Why are cereals not cooked entirely over the naked flame?

What is the price, weight, and measure of a package of Rolled Oats or
Wheat? Of a package of Cream of Wheat or Wheatena?

What is the cost of the quantity of cereal indicated in the recipes above?

Calculate the difference in the cost per pound of ready-to-eat and uncooked cereals.