AN INVESTIGATION OF CRUDE LIPASES FOR HYDROLYSIS, ESTERIFICATION, ANDTRANSESTERIFICATION

Nine commercially available powdered lipases were investigated for the ir catalytic ability to hydrolyze olive oil and synthesize 1-butyl ole ate by direct esterification and 2-ethyl-1-hexyl ester of rapeseed oil by transesterification. Under the experimental conditions used, a lip ase from Candida rugosa exhibited the highest hydrolytic activity at 8 8 U mg(-1) enzyme. Lipase from Pseudomonas fluorescens gave the highes t 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 lowe st hydrolytic activity at 1.5 U mg(-1) enzyme and also the lowest synt hetic 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. F inally, 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 obta ined from the regression analysis for the hydrolytic and synthetic act ivities for all lipases studied suggested little relationship between the hydrolytic and synthetic activities; however, the high multiple co rrelation 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 resu lts, the hydrolytic lipase activity may be of little value in predicti ng the synthetic activity, and in extreme cases, a lipase may exhibit no synthetic activity while possessing a high hydrolytic activity.