USE OF WHEAT II5 



millers do custom milling for an eighth toll, it is customary to 

 give thirty-six to thirt}"-seven pounds of flour and twelve to 

 fourteen pounds of mill feed for each bushel. While wide varia- 

 tions may occur on account of differences in the process of 

 milling and mixing, ordinarily about one-half the by-product is 

 bran, and the oth*er half shorts and middlings. 



The larger the endosperm and the smaller the embryo and 

 aleurone layer, the larger the percentage of flour obtained. The 

 evidence seems conclusive that the embr}^o and aleurone layer are 

 considerably higher in ash, and especially in phosphoric acid, 

 nitrogenous compounds and fat, than the endosperm, and that 

 the composition of wheat may vary on account of the proportion 

 of these to endosperm without any variation in the composition 

 of the endosperm. There is, therefore, no necessary relation 

 between the composition of the wheat grain and the composi- 

 tion of the flour therefrom. In general, however, grains with 

 high percentage of nitrogenous compounds produce flour wath 

 high percentage of these compounds and wdth high gluten con- 

 tent. (69) 



173. Grades of Flour. — The expert miller determines the 

 quality of the flour largely by feel and color. Great expert- 

 ness is acquired in judging of the granulations by the feel, which 

 depends both on the size of the flour particles and their form. 

 The quality of the flour also depends upon the per cent and 

 quality of the gluten. (70) The quality of the gluten may be 

 determined by the " baker's sponge test " by which the volume 

 of dough per unit of gluten as well as the time required to obtain 

 the maximum rise is determined. (204) 



Many trade names are given to different grades of flour by 

 manufacturers. Dealers have sought to obtain uniformity of 

 grading by a system of inspection similar to that employed for 

 whole wheat and other grains. As a guide for the inspector, a 

 series of standards is prepared and renewed from time to time 

 as required. The classification differs in different cities. Ir 



