Comparison of glycerolysis of sardine oil by Lipozyme 435 in solvent free and SC-CO2 media

Abstract

The efficiency of lipase catalyzed glycerolysis of sardine oil in solvent free and supercritical carbon dioxide media has been investigated. The immiscibility between substrates, glycerol and oil, is an important drawback to reach good high conversions of triglycerides (TAG) into monoglycerides (MAG) and diglycerides (DAG) in short reaction times. To improve mass transfer rates, emulsification of both reactants as reverse micelles (glycerol-in-oil) has been carried out. Enzyme-catalyzed reaction is an attractive alternative since the reaction can be carried out under mild conditions avoiding the oxidation of omega-3 fatty acids. In this work, a commercial immobilized lipase (Lipozyme 435) was employed as biocatalyst. The effects of SC-CO2 density on reaction rates and oxidation stability has been compared with those obtained in solvent free system at atmospheric pressure. The effect of temperature and pressure on reaction yield, oxidation state of reaction products and enzyme stability was studied. Good stability of Lipozyme 435 has been observed in both systems proving no thermal deactivation at temperatures higher than its optimum.