SYNTHESIS OF WAX ESTER THROUGH TRIOLEIN ALCOHOLYSIS - CHOICE OF THE LIPASE AND STUDY OF THE MECHANISM

Eight microbial lipases and one animal tissue lipase were tested for t heir ability to support alcoholysis between triolein and stearyl alcoh ol to produce wan ester. The lipases from Alcaligenes sp. and Chromoba cterium viscosum were shown to produce the best ester yield (about 53% ); however, the reaction was catalyzed in a shorter length of time usi ng the lipase from Alcaligenes sp. (5 h) as compared to the lipase fro m C. viscosum (200 h). The lipases from Mucor javanicus, Mucor miehei, and Pseudomonas fluorescens showed 35% ester yield within 150 h. The other lipases, i.e., the lipases extracted from porcine pancreas, Cand ida rugosa, Rhizopus javanicus, and Rhizopus niveus showed only low ca talytic activity (less than 20%). The lipase from Alcaligenes sp. was used for further investigations on the mechanism of the reaction. A re gioselectivity reward the sn-1,3-positions of the acylglycerols was sh own during the first hours of reaction. After 5 h when ester synthesis and triolein consumption stopped the continuous evolution of the conc entration of monoolein and diolein isomer forms was ascribed to isomer ization reactions. (C) 1998 Elsevier Science Inc.