THE RELATION OF CERTAIN PHYSICAL CHARACTERISTICS 

 OF THE WHEAT KERNEL TO MILLING QUiVLITY. 



By C. H. BAILEY. 



{Division of Agricultural Chemistry, Minnesota Agricultural 

 Experiment Station, St Paul, Minn.) 



The production of flour from wheat by the roller milling process 

 is a series of mechanical operations which have as their final object the 

 separation of the fibrous pericarp and the germ from the endosperm, 

 and the reduction of the latter to a fine powder. The more exact the 

 separation of these structures, the more desirable the process. In 

 actual practice a quantitative separation is never obtained, since a 

 plump wheat kernel may be from 82 to 85 per cent, endosperm^, and yet 

 only from 72 to 75 per cent, of the kernel is ordinarily recovered as 

 flour. The other 10 or 12 per cent, adheres closely to the pericarp and 

 germ fragments and is lost in the by-products or feeds. Since flour is 

 the most valuable product of milling, it follows that those wheats which 

 will yield the highest percentages of flour possess the greatest intrinsic 

 value. The term "milhng quality" is accordingly used by the writer 

 in this paper to express the potential yield of edible flour when milled 

 by the usual roller process. 



When the same general system of milhng is employed the relative 

 yields of flour will depend, other thing being equal, upon the percentage 

 of endosperm in the kernels. The quantitative determination of the 

 proportion of the several kernel structures is difficult, since it involves 

 the dissection of a sufficient number of kernels to furnish both a fair 

 average sample and a quantity of material which can be satisfactorily 

 weighed. There is a relation between the volume or displacement of 

 the kernel and the proportion of endosperm, however, of which advantage 

 may be taken. As shown by Brenchley^, the pericarp and germ are 



' Hunt. Cereals in America, p. 21, New York, 1908. 

 2 Brenchloy. Aim. Bot. 23, 117-139, 1909. 



