Effect of oxygen absorber on accumulation of free fatty acids in brown rice and whole grain wheat during storage

Because rapid rancidities of lipids in unpolished grains, such as brown rice and whole grain wheat, are often problematic, Suppressions of their lipid degradations during postharvest therefore important for their further utilization. In this study, effect of oxygen absorber on lipid deterioration in unpolished grain during storage was investigated. Kernels and flours of brown rice, rice with germ and whole grain wheat were stored for eight weeks at 4 °C and 26 °C, with and without oxygen absorber. Free fatty acids (FFAs) accumulation in the unpolished grains during storage was accelerated by polishing, milling and storage at high temperature (26 °C), because these storage conditions stimulated activities of their lipid hydrolyses. When oxygen absorber was added and the storage system was sealed, additional FFAs accumulations in these unpolished grains. Decreases both in absolute amounts of linoleic acids of the lipids and in total tocochromanols contained in these unpolished grains were depressed by addition of oxygen absorber to the storage system, which was confirmed by an anti-oxidative effect of oxygen absorber. These results suggested that introduction of oxygen absorber into the storage system of unpolished grains would be effective under the condition where their hydrolytic activities of lipids are suppressed.