WHEAT. Triticum sativum, Lam. Graminem.
largely for human food, chiefly as food-stuffs made from its flour, and in the form of breakfast foods. The by-products of its manufacture are used as stock-food. The grain, whole or ground, is also valuable for stock-feeding.
By nature it is an annual, although cultivation and improvement have modified its habits to a large extent. The tribe Hordem, in which wheat is included, is distinguished by its many-flowered spikelets which are arranged alternately on a stem or rachis, thus forming a spike. The close relation ship of wheat with barley, rye, rice and other cereals having the familiar spike head is readily observable.
The genus Triticum embraces wheat proper, but includes in its species and varieties several plants differing slightly in structure or habits of growth. These species and varieties are further broken up into types. Extensive studies of these with the object of classifying them on a rational basis have been made by scientists in recent years, but as yet a generally accepted arrangement has not been fully worked out. The classifications adopted are further confused with the distinctions made in the various markets of the world and the uses to which the grain is put.
Botanical characters.
The wheat grain.—The wheat seed or berry is the part of the plant of greatest economic value. It is also the one means of reproducing the plant. The seed, or grain, as it is generally called, is a hard, dry, oblong fruit with a longitudinal fur row on one side. The seed varies greatly in size, shape, color, hardness and composition, but retains under all conditions, distinct and common charac teristics. In size and weight it varies so that the number of grains in a pound ranges from 8,000 to 24,000, with a probable average of about 12,000. It is obvious that the number of seeds in a given quantity, either of weight or measure, will vary accordingly. Variations in the specific gravity range from 1.146 to 1.518.
In general, the shape is oblong with one end slightly pointed, but in some types the ends of the grain are much elongated, the berry itself being flattened, while in others it more nearly approaches a sphere. In color there is a wide range, from the paler shades of yellow through what is called amber, to deep red. Color is considered to have a close relationship to hardness of the grain and its composition.
The composition of wheat as reported by the Uni ted States Department of Agriculture is as follows: As will be noted, the grain contains 10 to 11 per cent of water. As a matter of fact, as grain is usually handled and shipped, the percentage of water would average much higher. It is well known that wheat transported from a dry climate to one more humid will absorb five to twenty-five per cent of additional weight in moisture. This is
particularly true when shipments are made by water. As wheat is handled in milling it is custom ary to add to it a considerable amount of water before being processed, as in its normal condition it is too dry. It will be seen that the grain has large absorptive powers ; and the same facts have been observed in the different manufactures pro duced from it.
Of the mineral elements in wheat, fully one-half is phosphoric acid, while the greater part of the remainder, consisting of one-third of the whole, is potash.
The wheat grain is characterized by a small embryo or germ, while the percentage of endo sin= constitutes a very large proportion of the entire contents, the ratio being as one to thirteen. The embryo, while having a high nutritive value, is not a desired element in the manufacture of flour, although it is utilized to a considerable extent in the production of certain cereal foods and always constitutes a most valuable by-product.
The endosperm is composed largely of pure starch cells which form the chief constituent of wheat flour as usually made. However, it contains proteids, which by their presence add largely to the value of flour as usually prepared in the form of baker's bread. These proteids have been classified as fol lows: (1) globulin, (2) albumin, (3) proteose, (4) gliadin and (5) glutenin. For all practical purposes only the last two named are considered in the manu facture of flour. These two proteids combined com pose what is known as gluten. It is the gluten contained in the starchy parts of the wheat grain which distinguishes it from flour made from cer tain other cereals, notably corn. Corn flour or meal is heavy and sodden when baked into bread as com pared with flour made from wheat or rye. The dif ference is due to the presence of gluten. In the process of bread-making the flour is made into a dough by the use of water and the addition of leav ening. When fermentation sets in, or, to use the common phrase, the bread begins to rise, carbonic acid gas is formed; this is imprisoned in the dough, which expands with the internal pressure and thus forms an open, porous loaf. The dough owes this elastic quality to the presence of the gluten. Gluten can be obtained from flour by washing the dough with water until all the starchy parts have been removed. The lump of gluten thus obtained will prove to be of a light, yellow color, tenacious and elastic. When dried, it will be semi-transparent, and closely resembles glue. The quantity of gluten in flour is important, but more depends on the quality. As it is not easy to determine the quality except by actual bread-making tests, millers usually select the wheats preferred on the basis of the per centage of total gluten contained.