Whole grains are an increasingly popular health food in America. However, shelf life of whole grains is compromised due to the presence of lipoxygenases in the bran and germ, which lead to rancidity and generation of oxidative byproducts. These byproducts reduce sensory quality and may have a degradative effect on vitamins in whole grain products. The purpose of this study was to determine the degree of lipid and vitamin degradation during long-term storage of three whole grains: whole wheat flour, brown rice, and rolled oats. We also examined vitamin loss after cooking to determine if oxidative byproducts had an effect on vitamins during typical household cooking. Whole wheat flour, brown rice, and rolled oats were stored for 12 months and periodically analyzed for conjugated dienes, free fatty acids, tocopherols, thiamin, and riboflavin. Whole wheat bread, steamed brown rice, and oat porridge were made from samples stored for 0 months and 12 months and were analyzed for thiamin and riboflavin. Conjugated dienes increased significantly only in rolled oats, while tocopherols decreased significantly in whole wheat flour and rolled oats and insignificantly in brown rice. Free fatty acids increased significantly in whole wheat flour and brown rice. Thiamin and riboflavin were stable in raw stored grains and cooked products made from stored grains with the exception of brown rice, in which we observed a significant decrease in thiamin after 12-month storage and cooking. These results suggest whole wheat flour, brown rice, and rolled oats experience significant lipid and tocopherol degradation, but it does not appear to affect thiamin and riboflavin in raw stored products. Cooking appears to cause degradation of thiamin after storage of brown rice, but thiamin and riboflavin were otherwise stable in these whole grains.



College and Department

Life Sciences; Nutrition, Dietetics, and Food Science



Date Submitted


Document Type





whole wheat flour, brown rice, rolled oats, whole wheat bread, thiamin, riboflavin, tocopherols, conjugated dienes, free fatty acids, storage, cooking



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Nutrition Commons