Glycerolysis of Fat by Lipase

Bioreactor for Enzymic Reaction of Fat and Fatty Acid Derivatives, Part VII

Abstract

Glycerolysis reactions of corn oil by Pseudomonas fluorescens lipase were studied batchwise in a small agitated vessel. The sampled reaction mixture was extracted with chloroform and the relative content of triglyceride (TG), 1, 2-diglyceride (1, 2-DG), 1, 3-diglyceride (1, 3-DG), 1-monoglyceride (1-MG), 2-monoglyceride (2-MG) and free fatty acid (FFA) of the condensed chloroform sample was determined using a TLC/FID analyzer. The effects of agitation speed on the initial rate of conversion were examined. Above 350rpm, the rate was maximum and constant. The time course of glycerolysis showed that at the beginning, the content of 1, 2-DG exceeded that of 1, 3-DG, but later, this was reversed. In two isomers of MG, 1-MG was detected almost exclusively, 2-MG being formed very little. The initial rates of conversion and formation of the products were proportional to enzyme concentration. No appreciable glycerolysis took place at very low water concentrations. No FFA was formed below 4% water concentration in glycerol. Above 4%, the initial FFA formation was proportional to water concentration to the 2.7th power. The dependence of the initial rate of conversion on the temperature obeyed the Arrhenius equation, giving 6.13kcal/mol of activation energy.
No variation in equilibrium composition was observed in the range of 1535% of the weight proportion of the oil to the total reaction mixture. The equilibrium composition did not change with variation in enzyme concentration or temperature from 2565°C. The equilibrium composition was significantly influenced by water concentration. Below 4% water in glycerol, no FFA was present in the product mixture. The composition of the product at 3.7% water concentration in glycerol was : 20.1% 1-MG, 0.3% 2-MG, 12.3% 1, 2-DG, 29.5% 1, 3-DG, 0.0% FFA, and 37.3% unreacted TG.