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.
MINERAL MATTER IN CEREALS.--Cereals contain seven or eight of the minerals required in the diet. Such a variety of minerals is sure to be valuable to the human body, as it is about one-half of the whole number required by the body for its maintenance. Since, as has already been explained, much of the mineral matter lies directly under the coarse outside covering, some of it is lost when this covering is removed. For this reason, the grains that remain whole and the cereal products that contain the entire grain are much more valuable from the standpoint of minerals than those in which the bran covering is not retained. If a sufficient percentage of minerals is secured in the diet from vegetables, fruits, and milk, it is perhaps unnecessary to include whole cereals; but if the diet is at all limited, it is advisable to select those cereals which retain the original composition of the grain.
WATER IN CEREALS.--Cereals contain very little water in their composition. This absence of water is a distinct advantage, for it makes their nutritive value proportionately high and improves their keeping quality. Just as the strength of a beverage is lowered by the addition of water, so the nutritive value of foods decreases when they contain a large amount of water. On the other hand, the keeping quality of cereals could scarcely be improved, since the germs that cause foods to spoil grow only in the presence of water. This low proportion of water also permits them to be stored compactly, whereas if water occurred in large amounts it would add materially to their bulk.
CELLULOSE IN CEREALS.--In addition to the five food substances that are found in all cereals, there is always present another material known as cellulose, which, as is pointed out elsewhere, is an indigestible material that occurs on the outside of all grains, as the bran covering, and covers the starch granules throughout the inside of the grain. In fact, it forms a sort of skeleton upon which the grains are built. As long as the cellulose remains unbroken, it prevents the grain from being digested to any extent. However, it forms a valuable protective covering for the grain and it has a certain value, as bulk, in the diet, a fact that is ignored by some persons and overrated by others. It is well to include at least some cellulose in cereal foods when they are taken in the diet, because its presence tends to make food less concentrated.
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foods high in sodium and
making sodium, visit the
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