Fatty acid esterification catalyzed by Candida rugosa lipase in lecithin microemulsion-based organogels

Lecithin microemulsion-based organogels (MBGs) were investigated as immobilization carriers for the esterification of lauric acid with butyl alcohol catalyzed by Candida rugosa lipase. Gelatin was used as the gelling component of the MBGs. The maximal reaction rate was obtained at a G(LW) (volume fraction of water in MBG) value of 75% v/v, a gelatin content of 18.5% w/v, and a lecithin concentration of 18 mM. The reaction proceeded under a reaction-controlled regime, and the reaction rate was influenced by MBG compositional changes. The effective diffusion coefficient of lauric acid varied with the MBG composition, while that of butyl alcohol remained constant. The partition coefficient of both substrates was affected by the MBG composition. Immobilized lipase was reused in a batch reaction system and its activity was successfully preserved for 720 h. During repeated batch reactions, lipase activity was enhanced, while the ester concentration at 48 h was between 30 and 40 mM. (C) 2002 Elsevier Science B.V. All rights reserved.