Prevention of hydrolytic rancidity in rice bran during storage

The effect of microwave heating, packaging, and storage temperature on the production of free fatty acids (FFA) in rice bran was examined. Freshly mil led raw rice bran was adjusted to 21% moisture content and heated in a micr owave oven at 850 W for 3 min. Raw and microwave-heated rice bran were pack ed in zipper-top bags or vacuum-sealed bags and stored at 4-5 or 25 degrees C for 16 weeks. FFA content-of bran was measured at 4-week intervals. Tota l FFA increased rapidly over the 16-week period from the initial value of 2 .5% in raw bran stored at 25 degrees C to 54.9% in vacuum bags and 48.1% in zipper-top bags. However, total FFA of raw bran stored at 4-5 degrees C in creased at, a slower rate from an initial value of 2.5 to 25.4% in vacuum b ags and 19.5% in zipper-top bags. After 16 weeks of storage, total FFA of m icrowave-heated bran stored at 25 degrees C increased from 2.8 to 6.9 and 5 .2%, respectively, for samples stored in vacuum bags and zipper-top bags. T otal FFA of microwave-heated samples stored at 4-5 degrees C did not change significantly with storage time. Results showed that hydrolytic rancidity of rice bran can be prevented by microwave heating and that the recommended storage condition for microwaved rice bran is 4-5 degrees C in zipper-top bags.