Acyl Migration of 2-Monoacylglycerols Rich in DHA: Effect of Temperature and Solvent Medium

Acyl migration of 2-monoacylglycerols (2-MAGs) rich in DHA is a universal reaction occurring during storage and structural lipid synthesis, and affects their nutritional value. In this study, their acyl migration was inves-tigated under different systems and temperatures. The enhanced temperature promoted acyl migration, leading to a 5.6-fold increase from 20 degrees C to 50 degrees C. The kinetic study indicated rate constants followed the order: hexane > solvent-free > dichloromethane > ethanol approximate to acetone approximate to acetonitrile > t-butanol, and positively correlated with log P of solvent. During acyl migration in ethanol, acetone, acetonitrile and t-butanol at 40 degrees C, DHA content in 2-MAGs was higher than in 1-MAGs, indicating slow acyl migration of DHA; while at 50 degrees C, the difference of DHA distribution was small, due to increasing acyl migration rate. The results suggest that acyl migration of different fatty acids can be regulated by changing conditions to enrich DHA at sn-2 position.