Intensification of lipase performance in a transesterification reaction byimmobilization on CaCO3 powder

Pseudomonas lipase was used as catalyst for the transesterification of doco sahexaenoic acid ethyl ester with glycerol under low pressure in a solvent free system. The biocatalyst performance was intensified greatly by prior a dsorption of lipase on very fine CaCO3 powder. CaCO3 particles played the r ole of a surfactant and of an enzyme transporter to the glycerol-ethyl este r interface. Microscopic analysis of the emulsified reaction mixtures revea led that CaCO3 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 f ree lipase, due to the larger interfacial area available for the enzyme act ion. The reaction with immobilized enzyme reached equilibrium at 96% consum ption 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 sam e reaction time. The prior immobilization of lipase on CaCO3 proved to be n ecessary for the operational stability of the catalyst by protecting the en zyme against inactivation. (C) 1998 Elsevier Science B.V. Al rights reserve d.