Intensification of lipase performance in a transesterification reaction by immobilization on CaCO 3 powder

Abstract

Pseudomonas lipase was used as catalyst for the transesterification of docosahexaenoic acid ethyl ester with glycerol under low pressure in a solvent free system. The biocatalyst performance was intensified greatly by prior adsorption of lipase on very fine CaCO 3 powder. CaCO 3 particles played the role of a surfactant and of an enzyme transporter to the glycerol-ethyl ester interface. Microscopic analysis of the emulsified reaction mixtures revealed that CaCO 3 particles stabilized the droplets of substrate by adsorption on their surface. The reaction rate, when the immobilized enzyme was used, was five times higher than that of the reaction performed with dissolved free lipase, due to the larger interfacial area available for the enzyme action. The reaction with immobilized enzyme reached equilibrium at 96% consumption of ethyl ester after 8 h of reaction time. In contrast, the reaction with free enzyme was far from equilibrium at only 43% conversion at the same reaction time. The prior immobilization of lipase on CaCO 3 proved to be necessary for the operational stability of the catalyst by protecting the enzyme against inactivation.