A rice mutant with a giant embryo has increased levels of lipophilic antioxidants- E vitamers and gamma-oryzanol fraction

Authors: Chen, Ming Hsuan; BERGMAN, CHRISTINE - University Of Nevada Las Vegas, Las Vegas, Nv; Grimm, Casey; McClung, Anna

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2019
Publication Date: 11/29/2019
Citation: Chen, M., Bergman, C.J., Grimm, C.C., McClung, A.M. 2019. A rice mutant with a giant embryo has increased levels of lipophilic antioxidants- E vitamers and gamma-oryzanol fraction. Cereal Chemistry. https://doi.org/10.1002/cche.10242.
DOI: https://doi.org/10.1002/cche.10242

Interpretive Summary: Consumption of whole grains has been linked to the reduced risk of developing several chronic diseases. These protective effects are thought to result from the effects of various bioactive compounds in the bran and germ fractions of whole grains. Among them the lipophilic antioxidants, tocopherols, tocotrienols and the '-oryzanol fraction in rice bran, have been proposed to have positive health effects. These lipophilic antioxidants in a giant embryo rice mutant were determined to evaluate its potential to be grown as a specialty rice variety. The whole grain giant embryo mutant has higher tocopherols and '-oryzanol fraction than its non-mutant wild type. It also produced higher bran fraction and higher lipid content than the wild type. This giant embryo mutant has the potential to be grown as a specialty rice variety for the purposes of isolating its bran, oil and lipophilic antioxidants for use by the food and cosmetic industries.

Technical Abstract: Lipophilic compounds in rice bran have health beneficial and functional properties. These lipophilic antioxidants in a giant embryo mutant (GEDrew) were determined to evaluate its potential as a specialty variety. The majority of the tocols in the embryo were in the form of tocopherols with a-tocopherol accounting for approximately 70%; while the tocopherols in bran ranged from 22-43% of total tocols. GEDrew had double the size of embryo and lower kernel weight than Drew, its wild type. On a per embryo basis, GEDrew had a higher quantity of tocols compared to Drew; however, on a weight basis, the concentration of tocols in GEDrew was less than Drew. The '-oryzanol concentration in embryos were the same for both the mutant and wild type. The smaller brown rice kernel size and bigger embryo size of GEDrew resulted in higher proportion of bran + embryo (w/w), which led to higher total tocopherols, tocotrienols and '-oryzanol in the whole grain of GEDrew relative to Drew. In conclusion, a rice mutant with a large embryo had an elevated level of '-oryzanol and tocols, both as a group and as individual homologues, in whole grains as compared to the wild type. It has the potential to be grown as a specialty rice variety for the purposes of isolating its bran, oil and lipophilic antioxidants for use by the food and cosmetic industries.