Kinetic modeling of lipase-catalyzed glycerolysis of olive oil

This work reports experimental data and the kinetic modeling of monoacylglycerols (MAG) and diacylglycerols (DAG) production from olive oil using a commercial immobilized lipase (Novozym 435) and tert-butanol as solvent. The kinetic modeling presented is based on the ordered-sequential Bi Bi mechanism considering glycerolysis and hydrolysis/esterification steps. Moreover, an empirical enzyme deactivation term, due to an excess of glycerol in the system, is proposed. The experiments were performed in batch mode evaluating the effects of temperature (40-70 degrees C), enzyme concentration (2.5-15 wt%) and glycerol to oil (G:0) molar ratio (0.5:1.5-6:1). Good conversions of MAG (similar to 65 wt%) and DAG (similar to 57 wt%) were obtained with relatively low enzyme concentrations (10 wt %) in relatively short reaction times (720 min) for different initial G:0 molar ratios. A very satisfactory agreement between the experimental data and modeling results was obtained under various conditions of enzyme concentration, glycerol to olive oil molar ratio and temperature, thus allowing a better understanding of the reaction kinetics. (C) 2010 Elsevier B.V. All rights reserved.