Lipid components, fatty acid distributions of triacylglycerols and phospholipids in rice brans.

Endogenous tocochromanols in extracted lipids from rice brans of the five cultivars were determined by high-performance liquid chromatography, and were investigated in relation to the fatty acid (FA) distribution of triacylglycerols (TAG) and phospholipids (PL). The dominant tocols were α-tocopherol and γ-tocotrienol, followed by α-tocotrienol and with much smaller amounts of γ-tocopherol and δ-tocotrienol. The lipids of these rice brans comprised mainly TAG (80.6-86.0wt.%), free FA (4.2-9.0wt.%), and phospholipids (5.5-6.7wt.%), whilst other components were also detected in minor proportions (0.2-2.1wt.%). The PL components included phosphatidyl choline (31.8-46.8wt.%), phosphatidyl ethanolamine (25.0-38.9wt.%) and phosphatidyl inositol (20.2-23.2wt.%). Comparison of these different cultivars showed, with a few exceptions, no significant differences (P>0.05) in FA distribution. FA distribution of TAG among the five cultivars was evident in the rice brans: unsaturated FA were predominantly concentrated at the sn-2 position and saturated FA primarily occupying the sn-1 or sn-3 position. These results suggest that the tocopherol content, lipid component, and FA distribution in rice brans are not dependent on the cultivation areas during the growing season.