Advances in Triacylglycerol Isomer Analysis in Edible Oils and Fats: Direct Separation of Positional and Enantiomeric Isomers by Chiral HPLC and Developments Since 2011

Abstract

Triacylglycerols (TAGs) are the major constituents of edible oils and fats, and their physical, nutritional, and metabolic properties depend not only on fatty acid composition but also on the binding positions of fatty acids on the glycerol backbone. Conventional gas chromatography and reversed-phase high-performance liquid chromatography (HPLC) have been widely used for TAG molecular species analysis; however, these methods provide limited information on positional and enantiomeric isomers. In 2011, we developed a chiral recycle HPLC method using polysaccharide-derived chiral stationary phases, enabling the direct separation of intact TAG enantiomers composed of long-chain fatty acids in edible oils and fats. Subsequent studies applied this methodology to palm oil, bovine milk fat, marine lipids, and egg yolk lipids, revealing characteristic distributions of TAG positional and enantiomeric isomers in natural systems. Technological advances, particularly the introduction of CHIRALPAK IF-3, enabled the simultaneous separation of positional and enantiomeric isomers without recycle operation and significantly expanded the scope of TAG isomer analysis. International studies in the Czech Republic and Finland further advanced the field through comprehensive characterization of TAG positional isomers and enantiomers and systematic investigations of chromatographic behavior. This review summarizes the historical development, methodological advances, and future perspectives of chiral HPLC-based TAG isomer analysis.

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