An investigation of crude lipases for hydrolysis, esterification, and transesterification

Nine commercially available powdered lipases were investigated for their catalytic ability to hydrolyze olive oil and synthesize 1-butyl oleate by direct esterification and 2-ethyl-1-hexyl ester of rapeseed oil by transesterification. Under the experimental conditions used, a lipase from Candida rugosa exhibited the highest hydrolytic activity at 88 U mg(-1) enzyme. Lipase from Pseudomonas fluorescens gave the highest conversion of oleic acid at about 95% in 24 h. Furthermore, lipases from C. rugosa and Rhizopus sp. resulted in the highest conversion of rapeseed oil at nearly 100%. Porcine pancreatic lipase showed the lowest hydrolytic activity at 1.5 U mg(-1) enzyme and also the lowest synthetic activity with the conversions of oleic acid and rapeseed oil at only 50% and 19% respectively. For the lipase from Rhizomucor miehei, only esterification and transesterification activities were related. Finally, for the lipase from Chromobacterium viscosum, no relationship between the hydrolytic and synthetic activities was observed. The low multiple correlation coefficients in the order of R = 1 0.35-0.40 obtained from the regression analysis for the hydrolytic and synthetic activities for all lipases studied suggested little relationship between the hydrolytic and synthetic activities; however, the high multiple correlation coefficient of R = 0.97*** for the conversion of oleic acid by esterification and rapeseed oil by transesterification by eight of the nine lipases studied suggested that there was a close relationship between esterification and transesterification. According to the results, the hydrolytic lipase activity may be of little value in predicting the synthetic activity, and in extreme cases, a lipase may exhibit no synthetic activity while possessing a high hydrolytic activity.