Lipase-Catalyzed Esterif ication of Glycerol and Fatty Acid in Reverse Micelles

Glycerol-fatty acid esterification has been conducted with lipase from R. delemar in water/AOT/isooctane reverse micellar media, with the major product being l-monoglyceride, a useful food-emulsifier. 1,3-Diglyceride was also synthesized, but to a much lesser extent. For a given set of initial conditions, the reaction productivity, measured in terms of the initial product formation rate, Vo, and the final or equilibrium concentration of product, is optimal for a particular concentration of each surfactant, fatty acid, glycerol, and water. Many of these optimal values correlate well with a "critical" region on the phase diagram. Also, results indicate lipase-catalyzed esterification stops due to the achievement of kinetic equilibrium except for a few cases where enzyme deactivation is severe. Dynamic light scattering was employed to examine the influence of water, glycerol, and fatty acid on micellar and interfacial structure. Results from this technique indicate enzyme kinetics are linked to interfacial phenomena and the presence of substrates at the interfacial region.