|Bergman, Christine - University Of Nevada Las Vegas, Las Vegas, Nv|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2019
Publication Date: 2/18/2019
Citation: Chen, M., Bergman, C.J., McClung, A.M. 2019. Hydrolytic rancidity and its association with phenolics in rice bran. Food Chemistry. https://doi.org/10.1016/j.foodchem.2019.01.139.
Interpretive Summary: Whole grain rice, which has the bran layer intact, contains more nutrients and health beneficial compounds than milled rice (bran moved) and its consumption is associated with a reduction of several chronic diseases. However, the bran layer is also where most lipids are deposited along with lipid degrading enzymes, lipase and lipoxygenase, which shorten the shelf life of whole grain rice. A set of diverse varieties were evaluated for the lipase induced hydrolytic rancidity levels (HR) in the bran and more than 15-fold variation in HR was found. Among the varieties, those with red or brown bran had lower HR than the purple, light brown and white brans. We also found that specific compounds in purple brans suppressed HR. Within the light brown bran color class, the typical bran color of U.S. cultivars, varieties having lower lipase activity than US cultivars were found and could be use as breeding materials to improve storage stability of US cultivars.
Technical Abstract: Whole grain rice, which has the bran layer intact, contains more nutrients and health beneficial compounds than its milled rice equivalent. Its consumption is associated with a reduction in the risk of developing several chronic diseases. However, the bran contains non-starch lipids deposited along with the lipid degrading enzymes, lipase and lipoxygenase, resulting in a relatively short shelf life for whole grain rice. We studied the genotypic diversity of lipase induced hydrolytic rancidity (HR) level in the bran of 134 diverse genotypes and found more than a 15-fold variation. Among the genotypes, those with red or brown bran had lower HR than the purple, light brown and white brans. Total phenolic content and anthocyanins were negatively correlated with the HR in purple brans suggesting their inhibitory effect on lipase during bran storage. In conclusion, low HR genotypes could be used as breeding materials to improve the storage stability of whole grain rice.