properties the gliadin of wheat. There is, however, in the rye no protein compound corresponding to the glutenin of wheat, and, therefore, rye flour does not form a gluten similar in quality to that of wheat, although it comes more nearly doing so than any other cereal. The gliadin of rye is soluble in alcohol, the leucosin of rye is soluble in water, and the edestin is soluble in a salt solution.
In a typical sample of American rye there will be found about 5.16 percent of gliadin, 2.27 percent of edestin and proteose, 0.55 percent of leucosin, and 3.14 percent of protein soluble in salt solution.
Adulteration of Rye Flour.—Rye flour is frequently adulterated by the admixture of flours of other cereals. Real rye flour is distinguished by the character of the starch granules, as shown in Fig. 31.
Rye starch grains are lenticular in form, and the largest grains are of about 50 microns diameter. They average somewhat larger than wheat starch grains and are characterized by many of the large grains having a fissure in the form of a slit, cross, or star, which is rare in wheat and barley. The rings and hilum are indistinctly seen in some of the grains.
Rye Bread.—This bread may be made leavened or unleavened, since the analogy in the property of its protein to that of wheat renders the leavening of rye bread somewhat more easy of accomplishment than that of the other cereals, with the exception of wheat.
Rye bread made of pure rye flour has a dark color, sometimes almost black. It is often baked long in advance of the time of eating and keeps well, is highly nutritious, and is the staple bread of many European countries.
A partial rye flour bread is made by mixing rye flour with other flours, such as wheat, barley, Indian corn, etc., and this is the kind which is commonly used in this country and in many portions of Europe where the light-colored breads are preferred to the dark.
The large consumption of bread made from rye and Indian corn indicates that even if the supply of wheat should become limited there is no reason to fear a famine of bread. It would be easy to substitute bread made wholly or in part of Indian corn and rye for that made wholly of wheat and thus to supply practically any demand for bread which the increasing population of the earth may make.
WHEAT (Genus Triticum).
In respect of human nutrition wheat is the most important of the cereals. It is grown in the temperate regions of almost every country, but does not flourish in tropical or subtropical countries.
In the United States the wheat is divided in respect of the period of its growth into two great classes, namely, winter or fall planted wheat and spring or spring planted wheat. Winter wheat is usually planted from September to November and spring wheat from the last of March to the last of April.
