The most widely used wheat food is bread, and this exists in many different forms and varieties. As made in the home bread is usually made from a yeast "sponge," prepared by mixing the yeast with a flour batter and leaving it to ferment for several hours. When the whole sponge is in active fermentation more flour is added to make a stiff dough. This dough is usually kneaded with the hands, which kneading process distributes the ingredients, especially the yeast, evenly through the dough. It is necessary to keep the bread sponge as well as the dough in a warm place in order that the yeast may do its work rapidly.

The yeast is a plant fungus, and fermentation is a process which simply represents the feeding of the yeast. The yeast consumes sugar, changing it into alcohol and carbon-dioxid gas. If sugar is not present, the yeast may use starch, breaking it up into sugar, and then further breaking it up into alcohol and carbonic-acid gas. Because of the fact that the yeast begins its action more readily with sugar than with starch many bread makers add a very small amount of sugar to the sponge. As this is all consumed in the fermentation of the sponge, it does not have the effect of sweetening the bread. In making the sponge milk is sometimes used instead of water for the liquid, and not infrequently "potato water," in which there is a considerable amount of starch. These variations in the liquid used for the sponge vary the quality and texture of the bread, the potato water making a bread which retains its moisture longer than bread made by other methods. Milk bread is likely to be finer in texture and is somewhat more nourishing than water bread because of the food value of the milk.

The action of the yeast is to cause the lightness of the bread, accomplished through the liberation of the carbon-dioxid gas, which cannot escape from the dough, being retained by the elastic gluten. This retained gas appears in fine bubbles through the dough, causing it to rise, increasing the loaf very greatly in size and making it light and spongy. Naturally, the best flour for bread making is a flour rich in gluten. These flours especially rich in gluten are called "strong flours," and are made from the hard wheat grown in northern districts. The wheat of softer berry, especially winter wheat from farther south, makes the "weak flour," so called, which contains a smaller proportion of gluten. While especially adapted for pastries and cakes, these flours are somewhat less adapted to bread making.

In the making of bread alcohol forms in the sponge and dough incident to the yeast fermentation. It is driven off in the baking; hence, properly baked bread contains absolutely no free alcohol. Furthermore, the yeast, which is composed of living plant cells, is killed. If the bread is not thoroughly baked some of the alcohol may be retained and the life of the yeast may not be completely destroyed; as a result such bread becomes sour within a day or so after it is baked, through a further fermentation of the alcohol, and a possible further activity of the yeast.

Graham bread is made in a general way similar to white bread and made from graham flour. Any advantage which graham bread possesses over white bread is due to the presence of the bran in the flour. This presence of the bran may serve to stimulate the peristaltic action of the intestinal walls, thus the graham bread is likely to be more laxative than the white bread. However, graham and whole wheat bread contain a larger proportion of indigestible material than is the case with white bread.

Hot breads may be made with yeast as a leavening agent, but such breads are more likely to be made with baking powder. Baking powder of the best quality is a combination of bicarbonate of soda and cream of tartar. When these two substances are brought together in the presence of moisture a combination is formed which results in formation of sodium tartrate, which remains in the bread after baking, and carbon dioxid, which escapes into the dough and causes it to rise, as does the carbon dioxid escaping in the process of yeast fermentation.

Some breads are unleavened, as is the case with the common white crackers, the lightness of these being partly due to the kneading of the dough. This process is done by machinery, and the result is somewhat more of a pastry than a bread. The lightness and flakiness of properly made pastries is due to the admixture of shortening, and in no small measure to the particular way in which the shortening is mixed with the flour.