2. ABUNDANCE OF PRODUCTION.--With the exception of the desert lands and the Arctic regions, cereals of some kind are grown over the entire world. Some varieties thrive in the hot countries, others flourish in the temperate regions, and still others mature and ripen in the short warm season of the colder northern climates. In fact, there is practically no kind of soil that will not produce a crop of some variety of grain. Since grains are so easily grown and are so plentiful, cereals and foods made from them furnish a large part of the world's food supply. Indeed, about one-fourth of all the food eaten by the inhabitants of the world, when it is considered as a whole, is made up of cereals.

3. ECONOMIC VALUE OF CEREALS.--The abundance of the world's grain supply makes the cost so moderate that many of the poorer classes of people in various countries, especially those in the Far East, live almost entirely on cereals. Still there is another factor that controls the low cost of cereals and grains and keeps them within the means of all classes of people, and that is their excellent keeping quality. They require very little care and will keep for an indefinite period of time. Because of their unperishable nature, they may be stored in large quantities and distributed to consumers as they are needed and at a price that is fairly uniform.

Since the cost of cereals is moderate, they should form a large proportion of the diet of the entire family, especially if the family's income will allow only a limited sum to be spent for food. Some cereals, of course, are much cheaper than others, and in purchasing this kind of food the housewife should be governed accordingly. Those which require an elaborate manufacturing process in their preparation for the market are the most expensive, but they have an advantage in that they require practically no preparation before serving. For the varieties that must be cooked, the cost of preparing the dish, especially if the price of fuel is high, must be taken into consideration, for unless some thought is given to the economical use of the fuel, as well as to the method of cooking employed, the cost of the prepared dish may be greatly increased. However, in the preparation of cereals, very little skill or energy is required and a general knowledge of the best methods for one of them can, as a rule, be applied to all.

4. CEREAL PRODUCTS.--Besides the cereals already mentioned, a number of products of cereals are extensively used in cookery, chief among them being flour, corn starch, and other starches. Although every housewife should possess knowledge of the uses of each of these, instruction in them is not given until later. This Section includes particularly the study of grains--whole, cracked, flaked, and those made into grits or meal--and the use and the serving of them, as well as ready-to-eat cereals, which are commonly referred to as breakfast foods. The only additional foods to which attention is given at this time are macaroni, spaghetti, and foods of a similar nature, for as these are made from wheat they are truly cereal products. In their preparation for the table, the rules that govern the other cereal foods apply also in a large measure to them.

COMPOSITION OF CEREALS

5. The composition of all cereals is similar, yet each one has its distinguishing feature. While all the five food substances--water, mineral matter, protein, fat, and carbohydrate--are to be found in cereals, they occur in different quantities in the various kinds. Some contain large quantities of protein and others practically none, and while certain ones have considerable fat others possess comparatively small quantities. A characteristic of all cereals, however, is that they contain a large amount of carbohydrate and a small amount of water. It is well to remember, though, that while the food substances of cereals are found in sufficient quantities to sustain life, they will not permit a person to live for long periods of time exclusively on this form of food. Likewise, it will be well to observe that the foods made from a certain grain will be quite similar in composition to the grain itself; that is, any change in the composition of the foods must be brought about by the addition of other substances.

6. All grains are similar in general structure, too. The largest proportion of carbohydrate lies in the center, this substance growing less toward the outside of the grain. The protein lies near the outside, and grows less toward the center. Fat is found in small amounts scattered through the entire grain, but most of it is found in the germ, which is a tiny portion of the grain from which the new plant sprouts. The mineral matter of cereals is found chiefly just inside the bran, or outer covering, so that when this covering is removed, as in the process of preparation for food, a certain amount of mineral matter is generally lost.

7. PROTEIN IN CEREALS.--The cereals are essentially a carbohydrate food, but some also yield a large proportion of protein. In this respect they differ from the animal foods that produce the principal supply of protein for the diet, for these, with the exception of milk, do not yield carbohydrates. The grain that contains the most protein is wheat, and in the form in which protein occurs in this cereal it is called gluten, a substance that is responsible for the hardness of wheat. The gluten, when the wheat is mixed with water or some other liquid, becomes gummy and elastic, a fact that accounts for the rubbery consistency of bread dough. Cereals that contain no gluten do not make bread successfully. Next to wheat, rye contains protein in the greatest amount, and rice contains the least. Although protein is the most expensive of the food substances, the kind of protein found in cereals is one of the cheaper varieties.

8. FAT IN CEREALS.--The fat of cereals helps to contribute to their heat-and energy-producing qualities, and, besides, it is one of the cheaper sources of this food substance. Of the eight grains, or cereals, used as food, oats and corn contain the most fat, or heat-producing material. The oil of corn, because of its lack of flavor, is frequently used in the manufacture of salad oil, cooking oil, and pastry fat. The fat that occurs in cereals becomes rancid if they are not carefully stored. In the making of white flour, the germ of the wheat is removed, and since most of the fat is taken out with the germ, white flour keeps much better than graham flour, from which the germ is not abstracted in the milling process.

9. CARBOHYDRATE IN CEREALS.--The food substance found in the greatest proportion in cereals is carbohydrate in the form of starch. Cereals contain many times more starch than any of the other food substances, rice, which is fully three-fourths starch, containing the most, and oats, which are less than one-half starch, the least. Starch is distributed throughout the grain in tiny granules visible only under the microscope, each being surrounded by a covering of material that is almost indigestible. In the various grains, these tiny granules differ from one another in appearance, but not to any great extent in general structure, nutritive value, or digestibility, provided they are cooked thoroughly. The large amount of carbohydrate, or starch, in cereals explains why they are not hard to digest, for, as is well known, starch is more easily digested than either protein or fat. This and the fact that some grains contain also a large amount of fat account for the high energy-producing quality of cereals. While it is safe to say that cereals are chiefly valuable for their starch, the tissue-building material in some grains, although in small proportion, is in sufficient quantity to place them with the protein foods.