THE MILLING OL 1UCE. 



c 2 represents a cross section of a rice grain, and shows, in addition 

 to the hull, the disposition of the seven layers. On the outside of 

 the hulled grain lie, in order, the epicarp, mesocarp, cross cells, and 

 tube cells. These four are frequently grouped together and called 

 the pericarp. Beneath this are the spermoderm, perisperm, and 

 aleurone layers. 



During the process of milling, there are removed, in addition to 

 the hull, most of the outer six coats and a portion of the seventh, 

 leaving only the starchy part of the endosperm surrounded by a 

 portion of the aleurone layer. Since the aleurone cells are rich in 



Fig. 2. — Cross section of the hull and outer portion of a rice grain, greatly magnified. 

 II, Hull ; P, pericarp (including the epicarp, mesocarp, cross cells, and tube cells) ; »S' J 

 spermoderm ; Pe, perisperm ; A, aleurone layer ; St, starch cells. 



protein and this constituent is also present in the protoplasm dis- 

 tributed through the endosperm, it is not surprising that only about 

 10 per cent of the protein of the hulled rice is removed by milling. 

 The oil, however, is largely contained in the germ, and about 85 

 per cent of the entire oil content of the hulled rice goes into the by- 

 products. Since the mineral salts of the hulled grain lie mostly in 

 the exterior layers, the proportion of salts is reduced nearly 70 per 

 cent by milling. Interesting, but of less importance, is the reduc- 

 tion of 70 per cent in the crude-fiber content by the removal of the 



