14 BULLETIN 570, U. S. DEPARTMENT OF AGRICULTURE. 



The yield of finished rice of all grades varied from 64 per cent for lot 

 D to 68.9 per cent for lot B, showing, as would be expected, that a 

 high yield of rice corresponds to a low yield of by-products. The 

 percentage of the bran coat taken off at the four stages varied greatly. 

 It would seem that more satisfactory milling results might be ob- 

 tained if it were possible to make the reduction at each stage more 

 nearly uniform. 



The chemical results given in Tables 8, 10, 12, and 14 show many 

 interesting features. The moisture of the rough rice is seen to be 

 mainly in the kernel, as the moisture of the hull in all cases was 

 markedly less than that of the other samples. A lower moisture 

 content was found in the several by-products than in the rice itself. 

 This may be due in part to the interior of the kernel having a higher 

 moisture content than the exterior portions, but probably is due 

 mainly to the drying of the by-products by the heat developed in 

 the milling process. This theory is supported by the fact that the 

 polish is of lower moisture content than are the brans. 



The ash in the stone-reel bran from the four lots of rice milled ap- 

 proximated 15 per cent, showing the presence of hulls in this bran. 

 This also is shown markedly by the ash insoluble in hydrochloric acid, 

 which averaged about 11 per cent, as compared with about 1 per 

 cent for the huller brans and polish. Lot C, composed of Japan-type 

 rice, was the only lot that showed a high insoluble ash in the first- 

 break huller bran. This is accounted for probably by the fact that 

 the small grains of rice of the Japan type do not separate so well in 

 the paddy machine as do other types of rice. 



A marked tendency for the ether extract to exceed protein was 

 observed in all brans, particularly in those from Blue Rose rice, which, 

 in general, are higher in ether extract than, and have approximately 

 the same amount of protein as, brans from the other types of rice. 

 The relation of ether extract to protein gives some indication as to 

 the addition of hulls, since hulls contain considerably more protein 

 than ether extract, and their addition to the bran tends to bring the 

 determinations for these two constituents more closely together than 

 would be the case if the bran were free from hulls. This has been 

 observed in the case of so-called 20 per cent brans, which have 

 been standardized to 20 per cent fat plus protein by the addition of 

 hulls. The trade custom of rating rice bran on the basis of the fat 

 plus protein content is of long standing. 



The percentage of crude fiber decreased markedly as the reduction 

 process was continued. The high figures for stone-reel bran are, of 

 course, due to the presence of hulls. The determinations of pentosans 

 and starch made on samples of lot A appear to furnish no information 

 regarding the products not given by the other figures. 



