Prevention of oxidative rancidity in rice bran during storage

The effect of microwave heat on lipoxygenase (LOX) activity in rice bran under various storage conditions was examined. Raw rice bran from the long-grain variety Lemont was adjusted to 21% moisture content and heated in a microwave oven at 850 W for 3 min. Raw and microwave-heated rice bran samples were packed in zipper-top bags or vacuum packs and stored at room temperature (25 degrees C) or in the refrigerator (4-5 degrees C) for 16 weeks. Samples were analyzed for LOX activity at 4-week intervals. LOX activity did not significantly change from its initial value at week 0 for zipper-top and vacuum-packed samples while stored at 4-5 degrees C for 12 weeks, but decreased at week 16. Vacuum packing did not show a significant impact on LOX activity during 16 weeks of storage. Microwave-heated samples stored in the refrigerator did not show significant change in LOX activity for up to 12 weeks but showed a significant(p < 0.05) decrease at 16 weeks. Results showed that oxidative rancidity of rice bran could be prevented by microwave heating the samples, packing in zipper-top bags, and storing at 4-5 degrees C for up to 16 weeks.