4 BULLETIN 330, U. S. DEPARTMENT OF AGRICULTURE. 



cellulose structure of epicarp and perisperm and a 30 per cent de- 

 crease in the quantity of pentosans. 



MILLING METHODS. 



/ EVOLUTION OF RICE MILLING. 



The rice hull is so stiff and hard as to be quite inedible, and its 

 removal from the grain is in reality the fundamental process of rice 

 milling. To accomplish this, various devices have been used in the 

 United States. The pounding of the grain in a wooden mortar with 

 a pestle by hand was succeeded by the employment of mechanical 

 devices for raising the pestle and by the use of larger mortars and 

 pestles covered with metal on their wearing surfaces. In some local- 

 ities a further refinement of the process consisted in substituting 

 revolving stones as a hulling agent before the rice was pounded. 



In Louisiana the same object was later accomplished by a machine 

 called the " plantation huller," in which the rough rice was hulled 

 and scoured by friction between corrugated iron surfaces. Modern 

 mills employ large revolving stones for removing the hulls and a 

 series of scouring machines for polishing the grain. 



PRIMITIVE METHODS. 



FARM MORTAR-AND-PESTLE MILLING. 



In early times, when the production was small and consumption 

 was confined largely to the producing area, simple and cheap methods 

 of milling were adequate. The farm mortar was made by burning 

 or scraping a conical cavity in a block of hard wood, and the pestle 

 was prep.ared from a cylindrical stick of similar wood by shaping and 

 pointing each end and cutting down the center to a size suitable for 

 a handle. Such a pestle was about 3 feet long and weighed from 

 10 to 15 pounds. Figure 3 shows the type of wooden mortar and 

 pestle formerly used in milling rice for home consumption. The 

 rough rice was pounded until practically all the grains had been 

 hulled and the broken hulls, acting as an abrasive, had scoured off 

 a considerable portion of the bran coat. The loose hulls and bran 

 were blown away by the wind when the pounded mass was poured 

 from an elevated pan to a receiver below. Before cooking such rice 

 it was necessary to remove by hand picking the remaining paddy 

 or unhulled grains, which were always present. Since the capacity 

 of a mortar was generally less than a bushel and the operations were 

 all done by hand, this method was inadequate for the milling of rice 

 except on a small scale. 



MORTAR-AND-PESTLE MILLS. 



As the demand for rice increased, it was found economical to em- 

 ploy larger mortars and mechanical means for pounding and winnow- 



