Abstract: The present study investigated the effect of microwave heating on the residual peroxidase activity in selenium-enriched and regular rice bran and the technological parameters were optimized through an orthogonal test (L9(34)) based on the residual peroxidase activity. The results showed that the optimal condition was power 1000 W, time 90 s and thickness 20 mm regardless of selenium-enriched and regular rice bran. The residual peroxidase activities of the stabilized selenium-enriched and regular rice bran under the optimal condition were 4.8% and 4.2%, and the moisture contents were 5.5% and 6.2%, respectively. Free fatty acid (FFA) levels of selenium-enriched and regular rice bran were below 15% in the treated samples and 92% in the control groups during the room temperature storage. And FFA levels were below 11% while 70% in the control samples during the chilled storage. In conclusion, the chilled storage could not inhibit the activity of lipase and microwave heating could significantly improve the stabilization of selenium-enriched and regular rice bran.

Key words: selenium-enriched rice bran, regular rice bran, microwave stabilizing, peroxidase activity, free fatty acid level