Esterification activity and stability of Candida rugosa lipase in AOT microemulsion-based organogels

Abstract

AOT microemulsion-based organogels (MBGs) were investigated as a reaction medium for the esterification of lauric acid with butanol catalyzed by Candida rugosa lipase. Gelatin was used as the gelling component of the MBGs. In a reactor fitted with a basket-type impeller, the initial reaction rate remained constant when the agitation rate was 0.83 s −1 or above. The reaction rate of immobilized lipase was enhanced with a high gelatin concentration. Under a fixed W G ( = [H 2O]/[AOT]) value of 100, the maximal reaction rate was obtained at an AOT concentration of 150 mM. The diffusion coefficient changed as a function of the gelatin and AOT concentrations, and its profile corresponded to that of the reaction rate. Immobilized lipase was also reused in a batch reaction system. In this case, the lipase activity was maintained successfully for 19 batch runs, that is, for 912 h. Water that accumulated in the MBGs was removed using a concentrated amphiphile solution.