Monitoring of lipase‐catalyzed transesterification between eicosapentaenoic acid ethyl ester and tricaprylin by silver ion high‐performance liquid chromatography and high‐temperature gas chromatography

A high‐resolution method based on silver ion high‐performance liquid chromatography (HPLC) and high‐temperature gas chromatography (HTGC) with on‐column injection was established for the separation of triacylglycerols (TAG) which contained eicosapentaenoic acid (EPA). A solvent system based on n‐hexane, 2‐propanol, and acetonitrile in HPLC for the separation of EPA‐containing TAG was developed. It was dependent upon the number of EPA molecules and their isomeric distribution on the glycerol backbone. This technique was used to monitor the incorporation of EPA onto specific positions on the glycerol backbone. For quantitative monitoring of the synthesis reaction of the TAG containing EPA, an HTGC analysis was developed. For monitoring of the synthesis of structured TAG containing EPA, transesterification of tricaprylin with EPA ethyl ester in a solvent‐free system was performed. The transesterification reaction using various lipases was studied at a different molar ratios of substrates, several initial water activities (aw), and various reaction temperatures.