Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2007
Publication Date: 8/11/2007
Citation: Yu, S., Nehus, Z.T., Badger, T.M., Fang, N. 2007. Quantification of vitamin E and gamma-oryzanol components in rice germ and bran. Journal of Agricultural and Food Chemistry. 55(18):7308-7313.
Interpretive Summary: It is well known that the Asian diet contains soy foods, and soy is thought to contribute heavily to the increased health benefits associated with that diet. However, what is not well appreciated it that Asians eat more rice than soy, and health benefits could also come from the rice. We have been studying rice and found it contains many phytochemicals that are biologically active. This report identifies and quantitates two important factors (vitamin E and gamma-oryzanol) in two important rice food sources: bran and germ. We found that each rice component has a unique profile of these phytochemicals.
Technical Abstract: Rice bran is a rich natural source of vitamin E and gamma-oryzanol, which have been extensively studied and reported to possess important health-promoting properties. However, commercial rice bran is a mixture of rice bran and germ, and profiles of vitamin E and gamma-oryzanol components in these two different materials are less well-studied. In the current study, vitamin E and gamma-oryzanol components in rice bran and germ were analyzed by liquid chromatography/mass spectrometry/mass spectrometry. The components were identified by electrospray ionization mass spectrometry (ESI-MS) with both positive- and negative-ion modes. Both deprotonated molecular ion [M - H]- and protonated molecular ion [M + H]+ found as the base peaks in spectra of vitamin E components made ESI-MS a valuable analytic method in detecting vitamin E compounds, especially when they were at very low levels in samples. Ultraviolet absorption was used for quantification of vitamin E and gamma-oryzanol components. While the level of vitamin E in rice germ was 5 times greater than in rice bran, the level of gamma-oryzanol in rice germ was 5 times lower than in rice bran. Also, the major vitamin E component was gamma-tocopherol in rice germ and gamma-tocotrienol in rice bran. These data suggest that rice bran and germ have significantly different profiles of vitamin E and gamma-oryzanol components. The method enables rapid and direct on-line identification and quantification of the vitamin E and gamma-oryzanol components in rice bran and germ.