ESTERASE-ACTIVITY AND FREE FATTY-ACID ACCUMULATION IN THE BRAN OF SELECTED RICE CULTIVARS

To increase our understanding of lipid degradation in rice bran, the e sterase activities of crude enzyme solutions extracted from rice bran were compared for 10 rice cultivars. The activities of rice cultivars Kinuhikari, Saikai191, and Hishiyutaka were higher than those of other rice cultivars we examined. Changes in the free fatty acid content of the polished bran from four rice cultivars were studied using by fluo rometric high-performance liquid chromatography using 9-bromomethylacr idine. Free fatty acids in the polished bran of Saikai191 and Hoshiyut aka accumulated more rapidly than the those of Tomochi396 and Koshihik ari, which supports the observation that the esterase activity in poli shed bran is cultivar-dependent. Furthermore, the species of free fatt y acids that accumulated in the polished rice bran differed depending upon the storage conditions. This suggests that the storage temperatur e and relative humidity affected the activities of several enzymes tha t participate in the lipid hydrolysis.