Characteristics and kinetics of lipase-catalyzed hydrolysis of olive oil in a reverse micellar system

Abstract

The hydrolysis rates of olive oil catalyzed by lipase were measured in a reverse micellar system using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) under various conditions. The maximum activity of lipase in the reverse micelles was obtained between pH 6.3 and 7.3. The dependence of the activity on the water content, Wo, was influenced by the concentrations of both AOT and lipase. The activity at Wo = 7 decreased with increasing lipase concentration when the AOT concentration was below 100 mol/m3. The stability of the lipase in the micelles decreased with increases in the value of Wo and in the concentration of AOT. The hydrolysis reaction catalyzed by lipase in the reverse micelles was interpreted by a reaction model based on the interfacial reaction between lipase adsorbed at the interface and the substrate in the organic phase. The rate is controlled by the desorption step of free fatty acids into the organic solution. The desorption rate constants of fatty acids produced were independent of the AOT concentration at a fixed Wo, and were of nearly the same order of magnitude as that obtained in the emulsion system.