ENZYMATIC TRANSESTERIFICATION OF PALM OLEIN WITH NONSPECIFIC AND 1,3-SPECIFIC LIPASES

The enzymatic transesterification of palm olein was conducted in a low -moisture medium with nonspecific and 1,3-specific lipases from microb ial sources. The enzymes were first immobilized on Celite, lyophilized for 4 h and then added to a reaction medium that consisted of 10% (wt /vol) palm olein in water-saturated hexane. The catalytic performance of the enzymes was evaluated by determining the changes in triglycerid e (TG) composition and concentrations by reverse-phase highperformance liquid chromatography (HPLC) and the formation of free fatty acids by titration. Studies with lipase from Candida rugosa showed that the de gree of hydrolysis was reduced by drying the immobilized preparation a nd that the best drying time was 4 h. In all cases, the transesterific ation process resulted in the formation of PPP, a TC initially undetec ted in the oil, and increases in the concentrations of OOO (1.3-2.1-fo ld), OOL (1.7-4.5-fold), and OLL (1.7-4.3-fold), where P, O, and L are palmitic, oleic, and linoleic acids, respectively. SOS (where S is st earic acid), another TG not detected in the oil, was synthesized by Rh izomucor miehei and Pseudomonas lipases, with the latter producing mor e of this TC. There was a corresponding decrease in the concentrations of POP, PLP, POO, and POL. PPP concentration ranged from 1.9% (w/w) f or Mucor javanicus lipase to 6.2% (w/w) for Pseudomonas lipase after 2 4 h. The greatest degree and fastest rate of change were caused by Pse udomonas lipase, followed by the enzymes from R. miehei and Aspergillu s niger. The effects of transesterification and hy drolysis of palm ol ein by the various lipases resulted in changes in the overall degree o f saturation of the triglyceride components. There seems to be no clea r correlation between the enzyme positional specificity and the produc ts formed. Possible mechanisms for the formation of PPP, OOL, OLL, OOO , and SOS are discussed.