Process optimization using response surface design for diacylglycerol synthesis from palm fatty acid distillate by enzymatic esterification

Diacylglycerols (DAG) were synthesized by lipase-catalyzed esterification of glycerol with palm fatty acid distillate(PFAD). Lipase from Rhizomucor miehei was used and the reaction was carried out at 45°C. After 24 h, the reaction productswere sampled and the DAG content was determined using high performance thin layer chromatography. A response surfacemethodology (RSM) was used to study the effect of substrate molar ratio (0.75 to 2.25 mol), enzyme concentration (2.0 to 3.0wt%) and the amount of molecular sieve (25 to 35 wt%) on the DAG yield. An analysis of variance (ANOVA) showed that 84%(R2 = 0.84) of the observed variation was explained by the polynomial model. The optimum conditions obtained from theresponse surface analysis were 1.23 mol for the molar ratio between fatty acid distillate and glycerol, 31.1 wt% molecularsieve and 2.32 wt% enzyme. Alkaline neutralization of the esterification products yielded neutralization residues containingapproximately 70% DAG.