Genotype and environment effects on Tocopherol, Tocotrienol, and y-Oryzanol contents of southern US rice

Authors: BERGMAN, CHRISTINE - US Department Of Agriculture (USDA); XU, ZHIMIN - Louisiana State University

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2003
Publication Date: 7/1/2003
Citation: Bergman, C.J., Xu, Z. 2003. Genotype and environment effects on Tocopherol, Tocotrienol,and
y-Oryzanol contents of southern US rice. Cereal Chemistry. 80(4):446-449.

Interpretive Summary: The bran layer of whole grain (brown) rice contains vitamin E families and gamma-oryzanol fractions. These compounds are antioxidants and reported to have health-benefit in reducing chronic disease incidence. Thus brown rice, rice bran, and rice bran extracts are good candidates for use in functional food. Variation of the contents of these antioxidants in US cultivars has not been reported. We selected seven rice cultivars from conventional U.S. long and medium grain varieties and specialty rice grown in four southern states for the study. In general, growing environment affected the concentration of vitamin E and gamma-oryzanol. Thus for selecting these traits, rice cultivars are needed to be evaluated in multiple years and locations. Among the seven cultivars, Cypress and Toro 2 had the highest concentrations of vitamin E and gamma-oryzanol, respectively.

Technical Abstract: Rice bran contains phytochemicals such as E vitamers (i.e., tocopherols and tocotrienols) and the y-oryzanol fraction that reportedly may have positive effects on human health. Brown rice, rice bran, and rice bran extracts are therefore attractive candidates for use in the development of functional foods. The objectives of this project were to quantify the effects of genetics versus environment on the tocopherol, tocotrienol, and y-oryzanol contents of Southern U.S. rice and to determine associations between the levels of these phytochemicals. Seven rice cultivars grown in four states during two years were studied. Averaged across all samples, the content of
-tocotrienol > y-tocotrienol >
- tocopherol > y-tocopherol, and the tocopherols and tocotrienols were 27.5 and 72.5% of the total E vitamer content, respectively. Total E vitamer content ranged from 179 to 389 mg/kg and y-oryzanol from 2,510 to 6,864 mg/kg. A low correlation between total E vitamer and y-oryzanol contents suggests that to obtain rice bran with high levels of both of these fractions, new cultivars would need to be produced using hybridization and selection. In general, growing environment had a greater effect on E vitamer and y-oryzanol levels than did genotype. Therefore, rice breeders selecting genotypes with optimized levels of E vitamers and y-oryzanol will need to grow their breeding material in multiple years and locations.