Hydrolysis of soybean oil by surfactant-coated lipase in organic solvents

The advantages of coating surfactants onto the lipases for catalyzing lipolytic reactions in organic solvents motivated this investigation. The fatty acids obtained from hydrolysis of soybean oil are of nutritional value and are beneficial to the cardiovascular system. A lipase from Candida rugosa was used to prepare a surfactant-coated lipase (SCL) for catalyzing the hydrolysis of soybean oil. The conditions for obtaining a superior SCL, including the kind of surfactant, weight ratio of surfactant / lipase and pH of the buffer solution were investigated. These factors significantly affected the catalytic power, yield of SCL, protein content and the coverage of lipase by surfactant. The results obtained were explained by the hydrophile-lipophile balance (HLB) of the surfactant and the log P (hydrophobicity) of the organic solvent. The optimum conditions for preparing SCL for enhancing the hydrolysis of soybean oil were pH = 5.0 and weight: ratio of Span 60 and lipase = 4/1. The catalytic activity of the SCL was 3.6 fold greater than powdered Lipase. The optimum conditions for hydrolysis were investigated by varying the organic solvent as well as the temperature and pH of the milieu. SCL exhibited the highest hydrolysis rate at 37 degreesC: in a buffer solution of pH7.0 with isooctane. A conversion rate of 96.28% was reached in 12.3 hr.