A Handbook of Health. Woods Hutchinson
different substances. Starches are insoluble in water; that is, although they can be softened and changed into a jelly-like substance, they cannot be completely melted, or dissolved, like salt or sugar. Sugar, on the other hand, is a perfectly soluble or "meltable" substance, and can soak or penetrate through any membrane or substance in the body. Therefore all the starches which we eat—bread, biscuit, potato, etc.—have to be acted upon by the ferments of our saliva and our pancreatic juice, and turned into sugar, called glucose, which can be easily poured into the blood and carried wherever it is needed, all over the body. Thus we see what a close relation there is between starch and sugar, and why the group we are studying is sometimes called the starch-sugars.
Wheat—our Most Valuable Starch Food. The principal forms in which starch comes upon our tables are meals and flours, and the various breads, cakes, mushes, and puddings made out of these. Far the most valuable and important of all is wheat flour, because this grain contains, as we have seen, not only starch, but a considerable amount of vegetable "meat," or gluten, which is easily digested in the stomach. This gluten, however, carries with it one disadvantage—its stickiness, or gumminess. The dough or paste made by mixing wheat flour with water is heavy and wet, or, as we say, "soggy," as compared with that made by mixing oatmeal or corn meal or rice flour with water. If it is baked in this form, it makes a well-flavored, but rather tough, leathery sort of crust; so those races that use no leavening, or rising-stuff, in their wheat bread, roll it out into very thin sheets and bake it on griddles or hot stones.
Most races that have wheat, however, have hit upon a plan for overcoming this heaviness and sogginess, and that is the rather ingenious one of mixing some substance in the dough which will give off bubbles of a gas, carbon dioxid, and cause it to puff up and become spongy and light, or, as we say, "full of air." This is what gives bread its well-known spongy or porous texture; but the tiny cells and holes in it are filled, not with air, but with carbon dioxid gas.
Making Bread with Yeast. There are several ways of lightening bread with carbon dioxid gas. The oldest and commonest is by mixing in with the flour and water a small amount of the frothy mass made by a germ, or microbe, known as yeast or the yeast plant. Then the dough is set away in a warm place "to rise," which means that the busy little yeast cells, eagerly attacking the rich supply of starchy food spread before them, and encouraged by the heat and moisture, multiply by millions and billions, and in the process of growing and multiplying, give off, like all other living cells, the gas, carbon dioxid. This bubbles and spreads all through the mass, the dough begins to rise, and finally swells right above the pan or crock in which it was set. If it is allowed to stand and rise too long, it becomes sour, because the yeast plant is forming, at the same time, three other substances—alcohol, lactic acid (which gives an acid taste to the bread), and vinegar. Usually they form in such trifling amounts as to be quite unnoticeable. When the bread has become light enough, it is put into the oven to be baked.
Note the cleanly way of handling the food.
The baking serves the double purpose of cooking and thus making the starch appetizing, and of killing the yeast germs so that they will carry their fermentation no further. Bread that has not been thoroughly baked, if it is kept too long, will turn sour, because some of the yeast germs that have escaped will set to work again.
That part of the dough that lies on the surface of the loaf, and is exposed to the direct heat of the oven has its starch changed into a substance somewhat like sugar, known as dextrin, which, with the slight burning of the carbon, gives the outside, or crust, of bread its brownish color, its crispness, and its delicious taste. The crust is really the most nourishing part of the loaf, as well as the part that gives best exercise to the teeth.
Making Bread with Soda or Baking-Powders. Another method of giving lightness to bread is by mixing an acid like sour milk and an alkali like soda with the flour, and letting them effervesce[8] and give off carbon dioxid. This is the mixture used in making the famous "soda biscuit." Still another method is by the use of baking-powders, which are made of a mixture of some cheap and harmless acid powder with an alkaline powder—usually some form of soda. As long as these powders are kept dry, they will not act upon each other; but as soon as they are moistened in the dough, they begin to give off carbon dioxid gas.
Neither sour milk and soda nor baking-powder will make as thoroughly light and spongy and digestible bread as will yeast. If, however, baking-powders are made of pure and harmless materials, used in proper proportions so as just to neutralize each other, and thus leave no excess of acid or alkali, and if the bread is baked very thoroughly, they make a wholesome and nutritious bread, which has the advantage of being very quickly and easily made. The chief objection to soda or baking-powder bread is that, being often made in a hurry, the acid and the alkali do not get thoroughly mixed all through the flour, and consequently do not raise or lighten the dough properly, and the loaf or biscuit is likely to be heavy and soggy in the centre. This heavy, soggy stuff can be neither properly chewed in the mouth, nor mixed with the digestive juices, and hence is difficult to digest. If, however, soda biscuits are made thin and baked thoroughly so as to make them at least half or two-thirds crust, they are perfectly digestible and wholesome, and furnish a valuable and appetizing variety for our breakfast and supper tables.
Disease germs multiply in the dark and damp of the basement. The clothing hanging up in this bakery is a very probable source of infection.
Bran or Brown Bread. Flour made by grinding the wheat-berry without sifting the husks, or bran, out of it is called "whole-wheat" meal; and bread made from it is the brown "bran bread" or "Graham bread." It was at one time supposed that because brown bread contained more nitrogen than white bread, it was more wholesome and nutritious, but this has been found to be a mistake, because the extra nitrogen in the brown bread is in the form of husks and fibres, which the stomach is quite unable to digest. Weight for weight, white bread is more nutritious than brown. The husks and fibres, however, which will not digest, pass on through the bowels unchanged and stir up the walls of the intestines to contract; hence they are useful in small quantities in helping to keep the bowels regular. But, like any other stimulus, too much of it will irritate and disturb the digestion, and cause diarrhea; so that it is not best to eat more than one-fifth of our total bread in the form of brown bread. Dyspeptics who live on brown bread, or on so-called "health foods," are simply feeding their dyspepsia.
"Breakfast Foods." The same defect exists in most of the breakfast cereals which flood our tables and decorate our bill-boards. Some of these are made of the waste of flouring mills, known as "middlings," "shorts," or bran, which were formerly used for cow-feed. The claims of many of them are greatly exaggerated, for they contain no more nourishment, or in no more digestible form, than the same weight of bread; and they cost from two to five times as much. As they come on our tables, they are nearly seven-eighths water; and the cream and sugar taken with them are of higher food value than they are. They should never be relied upon as the main part of a meal.
Corn Meal. Corn meal is one of the richest meals in nutritive value for its price, as it has an abundance of starch and a small amount of fat. It is, however, poor in nitrogen, and like the other grains, in countries where wheat will grow, it is chiefly valuable for furnishing cakes, fritters, and mushes to give variety to the diet, and help to regulate the bowels.
Oatmeal. Oatmeal comes the nearest to wheat in the amount of nitrogen or protein, but the digestible part of this is much smaller than in wheat, and the indigestible portion