Optimization of enzymatic methanolysis of soybean oil by response surface methodology

Abstract

AbstractEnzymatic methanolysis of refined soybean oil with methanol was investigated using Rhizomucor miehei lipase, Lipozyme RM IM, in n‐hexane for reaction times of 30 min. Response surface methodology (RSM) based on three‐level, three‐factor (variable) face‐centered cube design was used for the optimization of methanolysis. The independent variables that affect the methanolysis reaction conducted in n‐hexane are temperature (°C), enzyme/oil weight ratio, and oil/methanol molar ratio. A good quadratic model was obtained for the methyl ester production by multiple regression and backward elimination. A linear relationship was observed between the observed and predicted values (R2−0.9635). The effects of temperature and enzyme amount, which affected methyl ester content of the product (response) positively, were significant (P<0.01). The quadratic term of temperature and the interaction term of enzyme amount with temperature affected the response negatively (P<0.01). The interaction term of enzyme amount with substrate mole ratio had a positive effect on the response (P<0.05). Critical conditions for the response at which methyl ester content of the product was 76.9% were determined to be 50°C, 2.37 methanol/oil mole ratio, and 0.09 enzyme/oil weight ratio.