274 AGRICULTURAL CHEMISTRY 



gluten layer. The germ or embryo plant is present in 

 the lower part of the kernel and opposite the rounded 

 end. The germ constitutes about 6 per cent, of the 

 weight of the kernel. The main part of the seed is the 

 endosperm which is the floury portion, sometimes incor- 

 rectly spoken of as the starch cells, in reality composed of 

 starch, gluten, mineral matter, and other compounds in 

 small amounts. Additional information in regard to the 

 structure of the wheat kernel is given in Bulletin No. 32 

 of the Nebraska Experiment Station. 



380. Proteids of Wheat. Wheat contains the largest 

 amount of proteids of any of the cereals, and also proteids 

 of an entirely different character. There are five sepa- 

 rate proteids in wheat : (i) An albumin (leucosin), (2) 

 a globulin (edestin), (3) a proteose, and two insoluble 

 proteids called (4) gliadin, and (5) glutenin, which to- 

 gether constitute the gluten. Wheat gluten can be ob- 

 tained by washing a sample of dough from wheat meal or 

 flour with water to remove the starch and other non -glu- 

 ten compounds. The gluten mass from hard wheat is 

 usually elastic and tenacious, varying in quality according 

 to the nature of the wheat from which it was obtained. 

 The milling qualities of wheat, and the baking qualities 

 of flour are determined largely by the composition of the 

 gluten. 



Wheat gluten is composed of two proteids, gliadin and 

 glutenin ; these form about 85 per cent, of the proteids 

 of wheat. The gliadin may be extracted from either 

 gluten or flour with a 70 per cent, solution of alcohol, 

 and is obtained, after evaporating the alcohol, in the form 



