11. WINTER, OR SOFT WHEAT derives its name from the fact that it is planted in the autumn and is soft in texture. It is of less importance in the making of bread than spring, or hard, wheat, but it is the kind that has been grown for centuries and from which the varieties of spring wheat have been cultivated. It is a softer grain than spring wheat, because it contains less gluten and more starch. The flour made from it does not produce so elastic a dough mixture as does that made from the other variety of wheat; consequently, the finished product, such as bread, rolls, etc., is likely to be more tender and more friable, or crumbly. It is for this reason that winter, or soft, wheat is not used extensively for bread, but is employed for pastry flour or mixed with spring wheat to make what is called a _blend flour_, which may be used for all purposes.
12. STRUCTURE OF WHEAT GRAIN.--In its natural state, wheat contains all the food substances required for the nourishment of the human body in nearly the proper proportions, and in addition it has in its composition sufficient cellulose to give it considerable bulk. It has been estimated that the average composition of this grain is as follows:
PER CENT. Protein...................................... 11.9 Fat.......................................... 2.1 Carbohydrates................................ 71.9 Mineral salts................................. 1.8 Water........................................ 10.5 Cellulose..................................... 1.8 Total....................................... 100.0
So that the composition of wheat and the making of wheat flour may be more clearly understood, it will be well to observe the structure of a grain, or kernel, of wheat, which is shown greatly enlarged in Fig. 1. At _a_ is shown the germ of the young plant, which remains undeveloped until the grain is planted. This part contains practically all the fat found in the grain, some starch, and a small quantity of protein. At _b_ is shown the inside of the kernel, or the _endosperm_, as it is called, which is composed of starch granules interlaced with protein and mineral salts. Surrounding these, as at _c_, is a layer of coarse cells that contain mineral matter and protein, and between these cells and the outer husk, as at _d, e, f_, and _g_, are layers of bran, which are composed of cellulose and contain mineral salts and small quantities of starch and protein. Enveloping the entire kernel is a husk, or bran covering, _h_. This forms a protection to the rest of the grain, but it cannot be used as food, because it is composed almost entirely of cellulose, which is practically indigestible. The center of the grain, or the heart, is the softest part and consists of cells filled with starch. From this soft center the contents of the grain gradually grow harder toward the outside, the harder part and that containing the most gluten occurring next to the bran covering.