INTERESTERIFICATION KINETICS OF TRIGLYCERIDES AND FATTY-ACIDS WITH MODIFIED LIPASE IN N-HEXANE

The kinetics of lipase-catalyzed interesterification of triglycerides and fatty acids in organic media was studied. First, the lipase Saiken 100, Rhizopus japonicus, was modified by surfactant to form an enzyme precipitate in aqueous solution, which was well dispersed in organic solvents. This modified lipase catalyzed the interesterification of tripalmitin and stearic acid. The enzyme has 1,3-positional specificity and does not distinguish between stearic and palmitic acids. The kinetic model developed to describe the interesterification reaction system is based on mass balance of two consecutive second-order reversible reactions. The reaction rate constant, k, was determined by solving the differential rate equations of the reaction system and by expressing the value of k as a function of concentrations of the substrates with time. The model gave satisfactory results. The best value of the specific reaction rate constant k* that fits all experimental data was 1.2 . 10(-5) [L(2)/(mmol . mg biocatalyst . h)] under the reaction conditions in this study.