|BERGMAN, CHRISTINE - University Of Nevada|
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2015
Publication Date: 3/22/2016
Citation: Chen, M., Bergman, C.J. 2016. Vitamin E homologs and y-oryzanol levels in rice (Oryza sativa L.) during seed development. Cereal Chemistry. 93:182-188.
Interpretive Summary: Rice bran contains vitamin E compounds (tocopherols and tocotrienols) and gamma-oryzanol. These fat-soluble antioxidants have gained significant attention due to their potential health benefits and ability to increase vegetable oil stability. Further improvement of the concentrations of these antioxidants in US cultivars will add value to the rice crop. Recent reports indicate that immature cereal grains have high concentrations of bioactive compounds, which suggests that harvest of immature rice grains may be important for use in nutraceutical and functional food applications. Thus, understanding the accumulation of these fat-soluble antioxidants in the rice grain and evaluating the potential of harvesting rice at a grain development stage that optimizes their concentration are needed. We selected two diverse rice cultivars, Cypress, from the USA, and Teqing, from China, for the study. We found that the concentrations of some of these antioxidants remained constant from grain maturity to 15 days post-maturity, and thus would be a good time period for harvest. However, rice grain should be harvested during its immature stage in order to obtain the highest vitamin E concentration.
Technical Abstract: Vitamin E homologs (tocopherols and tocotrienols) and gamma-oryzanol have gained significant attention due to their proposed health benefits and ability to increase vegetable oil stability. Changes in the levels of these phytochemicals were examined during seed development. Rapid accumulation of tocopherols, tocotrienols and gamma-oryzanol occurred during early seed development. During the middle stage of seed development, the levels of tocopherols decreased sharply, the levels of tocotrienols either stayed the same or decreased slightly, while gamma-oryzanol continued to accumulate till maturity. The levels of these compounds remained constant from maturity to 15 days post-maturity. In conclusion, rice grain should be harvested during its immature stage in order to obtain the highest amount of tocopherols, while the amounts of the other phytochemicals that were studied can be optimized by harvesting grain at maturity.