PRODUCTION OF SPECIFIC-STRUCTURED LIPIDS BY ENZYMATIC INTERESTERIFICATION - ELUCIDATION OF ACYL MIGRATION BY RESPONSE-SURFACE DESIGN

Production of specific-structured lipids (SSL) by lipase-catalyzed int eresterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of byproducts. In this paper, the elucidatio n of acyl migration by response surface design was carried out in the Lipozyme IM (Rhizomucor miehei)-catalyzed interesterification between rapeseed oil and capric acid in solvent-free media. A five-factor resp onse surface design was used to evaluate the influence of five major f actors and their relationships. The five factors, water content, react ion temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points. All parameters b esides substrate ratio had strong positive influences on acyl migratio n, and reaction temperature was most significant. The contour plots cl early show the interactions between the parameters. The migration rate s of different fatty acids were also compared from three different set s of experiments during the lipase-catalyzed reaction. The best-fittin g quadratic response surface model was determined by regression and ba ckward elimination. The coefficients of determination (R-2) of the mod el were 0.996 and 0.981 for Q(2) value. The results show that the fitt ed quadratic model satisfactorily expresses acyl migration for the enz ymatic interesterification in the batch reactor used.