Lipase catalyzed glycerolysis of ratfish liver oil at stirred tank basket reactor: A kinetic approach

Abstract

Abstract The kinetics of the lipase (Novozym 435) catalyzed glycerolysis of ratfish liver oil has been studied at pilot plant scale. A model derived from a generalized Michaelis–Menten mechanism was developed to describe the rates of disappearance of triacylglycerols and diacylglyceryl ethers. Positive discrimination of the immobilized lipase against diacylglyceryl ether was accurately determined in the different data sets studied. More than 1.5 times faster glycerolysis of triacylglycerol compared to that of diacylglyceryl ethers was observed in each set of experiments investigated. Reutilization of the same batch of the biocatalysts was carried out in a stirred tank basket reactor to evaluate the enzyme inactivation. A first-order model for deactivation of the lipase was fit to the data sets. Three different sets of enzymatic glycerolysis were carried out. In all cases rapid inactivation of the immobilized lipase was observed. The half life of Novozym 435 under the glycerolysis conditions studied was approximately 145 h which indicates a deleterious effect of the reaction conditions assayed on lipase activity. After 5 lipase reutilizations of 24 h each, lipase was washed with hexane/ethanol 50/50 w/w but original lipase activity could not be fully restored.