The effects of germination and different milling degrees on the nutritional properties of rice bran

Rice bran is a nutritious by-product of rice processing that is yet to be fully developed. Although germination has been extensively studied for the processing of brown rice, information regarding its impact on rice bran obtained from such processing is limited. This study aimed to investigate the change of nutritional components in rice bran obtained from different milling degrees (2 %, 4 %, 6 %, and 8 %) after germination. The results showed that with the increase of milling degree, the contents of protein and GABA increased and the content of dietary fiber, phenolic compounds, ash, and lipids decreased. Meanwhile, germination significantly increased the content of protein (up to 40 %), total dietary fiber (up to 44 %), bound phenolic compounds (up to 18 %), and GABA (up to 37 %) in the rice bran, while decreasing the content of ash, free phenolic compounds and phytic acid. Notably, germination can significantly decrease the content of some heavy metals, such as As, Cd, and Pb, in the rice bran. Lipidomics analysis showed that germination can significantly improve the composition of lipids and generate more functional lipids. These results indicated germination combined with appropriate milling can significantly improve the application prospects of rice bran as a food ingredient.