Synthesis of structured phosphatidylcholine containing n-3 PUFA residues via acidolysis mediated by immobilized phospholipase A₁

Structured phosphatidylcholine (PC) was successfully synthesized by acidolysis of PC derived from soybean with n-3 polyunsaturated fatty acids (PUFA) obtained from fish oil using an immobilized phospholipase-A₁ from Thermomyces lanuginosus/Fusarium oxysporum as the biocatalyst. The effect of water activity in the range from 0.43 to 0.93 on n-3 PUFA residue content was investigated. The immobilized phospholipase was more active at water activities greater than 0.53. The yield of PC decreased as the water activity increased from 0.43 to 0.93. The yield of lysophosphatidylcholine (LPC) increased significantly during the first 4 h of reaction as a consequence of hydrolysis of the PC. As the enzyme loading increased, the proportion of n-3 PUFA residues in the PC and LPC present at various times in the mixture of these species increased to as much as 15% of the total weight of substrate. For all enzyme loadings tested, both the proportion of n-3 PUFA residues in the total PC (unreacted and modified) and the production of LPC increased significantly when the reaction time was increased, although differences in n-3 PUFA content were observed. When both the n-3 PUFA content of the PC and the total yield of PC are considered, the optimum water activity and enzyme loading for production of structured PC and LPC are 0.65 and 15%, respectively.