Suppression of acyl migration in enzymatic production of structured lipids through temperature programming

Acyl migration in the glycerol backbone often leads to the increase of by-products in the enzymatic production of specific structured lipids. Acyl migration is a thermodynamic process and is very difficult to stop fully in actual reactions. The objective of this study was to investigate the feasibility of suppressing acyl migration by a programmed change of reaction temperature without loss of reaction yield. The model reactions were the acidolysis of tripalmitin with conjugated linoleic acid (CLA) or with caprylic acid (CA) targeted for human milk fat substitutes. Acyl migration was considerably inhibited in the temperature-programmed acidolysis of PPP with CLA or CA, with only slight reduction of acyl incorporation, the reaction leading to the required products. Acyl migration was reduced by 29% (35 h) and 45% (48 h), respectively, in the acidolysis of PPP with CLA under solvent and solvent-free systems, in comparison with 37% (35 h) and 61% (48 h), respectively, for the acidolysis of PPP and CA. Acyl migration in the acidolysis of PPP with CA was, in general, lower than the acidolysis of PPP with CLA in both systems. Temperature programming was more prominent in solvent-free systems for the reduction of acyl migration. Acyl incorporation was not significantly affected by temperature programming. The study suggests that it is feasible to reduce acyl migration by programmed change of acidolysis temperature without significant loss of reaction yield.