Optimisation of Novozym‐435‐catalysed esterification of fatty acid mixture for the preparation of medium‐ and long‐chain triglycerides (MLCT) in solvent‐free medium

Novozym‐435‐catalysed esterification of caprylic acid, capric acid and oleic acid with glycerol for the synthesis of medium‐ and long‐chain triglycerides (MLCT) in vacuum and solvent‐free system was investigated in this study. Response surface methodology with a three‐level, four‐factorial design was applied to optimise the enzymatic esterification for the synthesis of MLCT. The optimum conditions were as follows: reaction temperature 90 °C, 4.80 wt% enzyme load (relative to the weight of total substrates) and substrate molar ratio (fatty acids/glycerol) of 3:1 and 12.37 h. Under above‐mentioned conditions, Triglycerides (TG) yield, MLCT and the residual free fatty acids (FFA) content in the product were 93.54%, 72.19% and 4.21%, respectively. The content of caprylic acid, capric acid and long‐chain fatty acids of TG was 24%, 10% and 66%, respectively. Novozym 435 in the study showed no selectivity for the different fatty acids and also could be used 14 times without obvious loss of enzyme activity.