Esterification reactions of heptanoic acid with heptanol, catalyzed by Candida lypolytical (CL) lipase, was studied in water-in-oil microemulsions formed by water/bis-(2-ethylhexyl) sulfosuccinate sodium (AOT)/isooctane. Kinetic studies showed that the reaction follows a Ping-Pong Bi Bi mechanism with inhibition by both substrates. The values of all apparent kinetic parameters were determined. Lipase has also been immobilized in gelatin-containing AOT microemulsion-based organogels (MBGs) without any loss of catalytic activity. These lipase-containing MBGs prove to be novel solid-phase catalysts for use in apolar organic solvents and have good storage stability. These lipase-containing MBGs retained its higher activity after many runs esterification reactions.

Key words: MICROEMUSION, LIPASE, ENZYME CATALYSIS, FIXED ENZYME, ESTERIFICATION