Optimisation of n-octyl oleate enzymatic synthesis over Rhizomucor miehei lipase

Octyl oleate is a useful organic compound with several applications in cosmetic, lubricant and pharmaceutical industry. At first, the enzymatic synthesis of n-octyl oleate by direct lipase-catalysed esterification of oleic acid and 1-octanol was investigated in a stirred batch reactor in solvent-free system. A systematic screening and optimisation of the reaction parameters were performed to gain insight into the kinetics mechanism. Particularly, enzyme concentration, reaction temperature, stirrer speed, water content, substrates concentration and molar ratio were optimised with respect to the final product concentration and reaction rate. The kinetics mechanism of the reaction was investigated. Finally, a comparison of the experimental results obtained in a solvent free-system with those using two different solvents, supercritical carbon dioxide (SC-CO2) and n-hexane, was proposed. It resulted that in SC-CO2 higher concentration of the desired product was attained, requiring lower enzyme concentrations to achieve comparable conversion of free fatty acid into fatty acid ester.