Prevention of oxidative rancidity in rice bran during storage

The effect of microwave heat on lipoxygenase (LOX) activity in rice bran un der various storage conditions was examined. Raw rice bran from the long-gr ain variety Lemont was adjusted to 21% moisture content and heated in a mic rowave 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 temperatu re (25 degrees C) or in the refrigerator (4-5 degrees C) for 16 weeks. Samp les were analyzed for LOX activity at 4-week intervals. LOX activity did no t 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 decre ased at week 16. Vacuum packing did not show a significant impact on LOX ac tivity during 16 weeks of storage. Microwave-heated samples stored in the r efrigerator did not show significant change in LOX activity for up to 12 we eks but showed a significant(p < 0.05) decrease at 16 weeks. Results showed that oxidative rancidity of rice bran could be prevented by microwave heat ing the samples, packing in zipper-top bags, and storing at 4-5 degrees C f or up to 16 weeks.