In situ lipase-catalyzed transesterification in rice bran for synthesis of fatty acid methyl ester

Fatty acid methyl ester (FAME) were synthesized via in situ lipase-catalyzed transesterification in rice bran without additional catalyst. With this method, FAME were synthesized directly from oil in rice bran by simply adding methanol, with the aid of rice bran lipase already existing in rice bran. The effects of temperature, molar ratio (oil in rice bran to methanol), and water content of the rice bran were investigated. The yield of FAME and the free fatty acid content were monitored as a function of reaction time. The optimum conditions were a temperature of 40 °C, a molar ratio of 1:6, and a water content of 12%. Under the optimum conditions, the FAME yield of 83.4 wt% was obtained after 12 days. To further increase the FAME yield, the transesterification was repeated using the rice bran obtained from the first transesterification. The oils in rice bran that could be converted to FAME were completely transformed throughout the repeated transesterification.