Preliminary study on the effect of milling technology on the key components of rice bran

Abstract

To improve the utilization level of rice bran, it is very important to study the accurate separation of key components in rice bran. In this paper, the influence of grinding wheel type, grinding speed and grinding time on the contents of key components in rice bran, such as wax, crude fat and crude protein, was studied, and was characterized and modeled by scanning electron microscopy (SEM), multiple regression analysis and correlation analysis. The results showed that the key components in brown rice were distributed alternately from the outside to the inside, which were wax ester layer, fiber layer, fat-protein layer and starch layer. The highest content of the key components in rice bran and its milling technology combination were of wax 0.67% (860 rpm, 1.0 min), crude fat 18.37% (1 060 rpm, 1.0 min), crude protein 18.59% (960 rpm, 2.0 min), crude fiber 16.85% (760 rpm, 0.5 min) and starch 41.12% (1 060 rpm, 2.5 min), respectively; Grinding wheel type had a very significant impact on wax content and crude fiber content (P<0.01), milling time has a very significant impact on rice bran yield and starch content (P<0.01), except for crude protein content, milling speed has a significant impact (P<0.05); Crude fiber had the highest significant correlation with other variables as a whole, correlation coefficient scores were of 0.84 (wax), 0.83 (crude fat), 0.73 (crude protein), –0.69 (starch) and –0.42 (rice bran yield), respectively. The accurate separation of key components of rice bran can be realized by the combination of fine milling and coarse milling.

Keywords

• milling technology
• rice bran
• wax
• crude fat
• crude protein