Novel route to mono- and diglycerides synthesis in miniemulsion catalyzed by lipases

Abstract

In summary, it could be shown that the lipolysis and glycerolysis in miniemulsion catalyzed by lipases lead to a significant increase of selectivity and presents an important route to obtain mono- and diglycerides. The miniemulsion offers an interfacial area, which allows increasing the yields and the kinetics of reactions. The reaction mechanism of most lipases is ruled by the interfacial activation between the oil phase and the aqueous phase. In this dissertation, a screening of lipases has been done and a sn-1,3 specific lipase was chosen not only to study the lipolysis and the glycerolysis in miniemulsion but also the influence of the homogeneity of the miniemulsion and the influence of the miniemulsion interfacial area through the variation of the miniemulsion droplet size. First of all, the lipolyses of tricaprylin catalyzed by the Rhizopus Arrhizus lipase, by the Pseudomonas Cepacia lipase, and by the Rhizomucor Miehei lipase were carried out and compared using the free fatty acid titration and 1H-NMR. Secondly, the homogeneity of the miniemulsion was observed to be a parameter influencing not only the activity but also the regioselectivity. Thirdly, the miniemulsion specific surface area was observed to play a determining role in the interfacial activation. This variation shows a relation between the lipase catalytic activity and the miniemulsion specific surface area. Fourthly, the glycerolysis reaction of tricaprylin by Rhizopus Arrhizus lipase in miniemulsion was studied. Finally, the hydrolysis of tricaprylin by weak bases in miniemulsion was performed to study their selectivity and activity. Like the caustic soda, some weak bases show a strong uncontrolled activity until they are used at high concentrations and under defined temperature conditions. Otherwise, the activity of the weak bases remains low. A thermodynamic selectivity is observed leading to the preferential formation of the thermodynamic stable isomers, 1,3-diglyceride and 1-monoglyceride