With this chapter we begin the study of another group of food substances, the carbohydrates, which is divided into two subdivisions, starches and sugars. These may look alike when in powdered form, but they taste very differently and are quite different in their chemical composition. The sugars will be left to a later chapter.

When looked at under the microscope, raw starch is seen to be made up of a mass of cells, each with a woody coat, embedded in a network of woody fiber. The markings on the woody coat of the small granules differ with the source of the starch; that from the potato is marked in one way and that from oats, barley, and rice in still different ways, so that each can be readily detected by close examination. When mixed with cold water, starch does not dissolve, but settles on standing. When, however, this mixture of starch and water is heated, it undergoes a chemical change. The woody coats of the starch granules are broken open by heat, as is also the woody fiber framework of the starch itself, permitting the starch to swell, and forming a thick paste with the water. This is said to be the hydrolysis of the starch, and unless starch has gone through this change, it cannot be properly acted upon by the digestive juices.

If this paste is heated further, it will become thinner until finally it is a watery liquid again. This is due to the fact that the starch has undergone a further chemical change, gradually becoming first a gum called "dextrine," and then a sugar known as "maltose." This change in the chemical form of the starch can be produced more rapidly by dry heat. When flour is browned on the pan for brown gravy, we are making dextrine from some of the starch granules. Since dextrine is soluble in water, the browned flour will not thicken as well as ordinary flour, and more must be used to the same proportion of water. We also dextrinize the starch in our bread when we make a slice of toast, which is the reason why a piece of dry toast is more easily digested than a slice of fresh bread.

Changes starch

Undergoes

Starch is found exclusively in the vegetable kingdom. It is the form which nature takes for the storage of food for the use of the plant at some future time. Usually this storehouse of food is laid by for the nourishment of the seedling which will make the new plant; hence starch is found in seeds or tubers where the embryo lies dormant. Starch, as human food, is taken primarily from the seeds of plants belonging to the grass family, such as wheat, rye, oats, barley, and rice. We also find it in the kernel of the corn, in the tuber of the potato, and in the root of some tropical plants which gives us arrowroot and tapioca. Sago is prepared from the pith of several species of palms, natives of the East Indies. But all of these are the same chemical substance though appearing on the market in different forms.

The term "cereal" has two distinct meanings as generally used. The correct use of the term is when it is applied to the grain itself, while its secondary meaning is the product made from the grain in the form of a breakfast food.

The structure of the kernels of all grain is much the same. The outside is well protected by several bran coats - five in the case of wheat. The inside is divided into two parts, one, much larger than the other, is called the "endosperm," and the smaller one is known as the "germ."In the germ we find protein material, since here we have the material which will eventually form the new plant. We also find in the germ whatever fat there is in the grain. It contains minute quantities of substances known as "enzymes," or unorganized ferments, which enable it to utilize for food the starch material in the endosperm. The endosperm itself, along with its mass of starch granules embedded in woody fiber, contains a network of protein material. This particular protein material is known as "gluten," and is found in greater quantity in wheat and rye than in any other cereal. It is because of this substance that wheat and rye make a porous loaf of bread. The Biblical phrase, "Except a seed fall into the ground and die, it cannot live," is literally true, since the life of the seedlet depends entirely upon the fermentation of the starch in the grain, as it cannot be used for food until it is turned through fermentation into the soluble form of sugar.

Source of starch

The cereal grains have been used for human food for many hundreds of years. It is one of the wonders of nature that a grain suitable as a food for the people of different climates grows abundantly in those climates. Rice, for instance, which has the lowest fat content of any of the grains, grows in warm climates where the people do not need fatty food; while oats and corn, the two that are richest in fat, are indigenous to cold climates where fat is essential. The grains were first used whole, being parched on hot stones or in ashes. Later it was found to be more convenient to use them after they had been cracked by pounding between stones and the coarser bran removed. In this form they were boiled with water and used as mushes. Still later this process was carried further and meals were made from the grain by a prolonged pounding in a mortar with a pestle or between stones. The woman of the primitive race was the one to prepare the meals, until later, animals were harnessed in such a manner as to turn one stone upon another.

Structure of kernel

Use of grains for food

As the ingenuity of the races increased, the forces of nature were used for this grinding. Stones were still used as grinding surfaces, but the upper millstone was now turned by wind or water. Survivals of these old-fashioned mills are still to be found on Long Island and in the South. Meal from such a mill contained the whole of the kernel of corn or wheat, with the exception of the outermost bran coats which were sifted out. This produced a meal containing fat which grew rancid on standing and could not be kept for any length of time. As the development of machinery progressed, the old-fashioned millstones were replaced by modern steel machinery.