Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: July 12, 2008
Publication Date: July 13, 2008
Citation: Chen, M. 2008. Selection of brown rice (whole-grain) varieties with long shelf life. Texas Rice, Highlighting Research 2008. http://beaumont.tamu.edu/eLibrary/Newsletter/2007_Highlights_in_Research.pdf. pp. VII-IX.
Studies have associated consumption of whole grains and whole-grain products with reduced incidence of chronic diseases such as cardiovascular disease, diabetes, and cancer. Because of the health benefits of eating whole grains, one of the key recommendations in the 2005 USDA dietary guidelines for Americans is that at least half of the Grain Group should come from whole grains or whole-grain products, which is the amount of 3 ounce-equivalents (one ounce-equivalent is, for instance, ½ cup of cooked brown rice). Brown rice is relatively high in dietary fibers, vitamins, minerals, and antioxidants compared with milled rice. However, brown rice, as with all other whole-grain cereals, has a short shelf life. This is due in part to the activity of lipase enzyme, which breaks down lipids causing development of an off-flavor. It has been suggested that de-hulling paddy or rough rice to produce brown rice disrupts the outer bran layer resulting in the contact of lipase enzymes with the lipid. Selection for rice varieties that are low in lipase activity might prolong the shelf life of brown rice and delay the development of off-flavor. We analyzed 109 rice varieties collected from the National Small Grain Collection for their lipase activity and storage stability. We established that rice with lower lipase activity has higher storage stability. The lipase activity in this rice selection ranged from 0.92 to 5.34 units. The average lipase activity was around 2.47 units. Two commonly grown US rice cultivars have higher lipase activity than average. The results suggest that opportunity exists for improving the shelf life of brown rice by lowering rice lipase activity through the use of breeding techniques.