Studies on the application of microwave heating for stabilization of rice bran was performed to find out various variables related to reduction of microwave treatment time.
The samples with 10.4% of moisture content heated slowly and required a longer treatment time whereas samples with 19.3% of moisture content heated more rapidly and required microwave exposure of a shorter time for fixed inactivation of lipase. The rate of microwave heating in 970 w of power input was double that of 470 w of power input but the effectiveness of enzyme inactivation was more efficient in 970 w than in 480 w, and volume of samples exposed to microwave irradiation had nearly no effect on residual lipase activity. Consumption energy could be decreased as sample weight increased in one microwave treatment.
Acid value and lipid extractibility of original rice bran was 19.2 and 97.2% whereas acid value and lipid extractability after microwave treatment was also 19.1 and 96.7%, respectively. Effectiveness of lipase inactivation during storage was not positive by effect of moisture content.
Multiple regression analysis was used to obtain prediction equation to measure individual and combination effect of moisture content, sample weight and microwave treatment time on residual lipase activity.