Analysis of sn-1(3)- and sn-2-short-chain acyl isomers of triacylglycerols in butteroil by gas-liquid chromatography

The aim of the study was to determine major triacylglycerols (TG), and sn-1(3) and sn-2 isomers of butyryl and caproyl TG in butteroil (BO) and interesterified butteroil (IBO) by gas-liquid chromatography (CLC) and silver ion column chromatography. Altogether, 112 molecular species of TG were synthesized by interesterification and their retention indices were determined. Molar empirical correction factors for TG were determined using linear calibration. Retention indices showed that sn-1(3) and sn-2 isomers of the TG containing one short-chain acyl (butyrate, caproate) and two long-chain acyls (laureate, myristate, palmitate, stearate, and oleate) were separated on a phenyl (65%) methylsilicone column. The difference between retention indices of 1(3)- and 2-short-chain acyl isomers ranged from 14 to 19, and from 9 to 16 for butyrates and caproates, respectively. The proportion of sn-2 isomers of butyrates averaged 1.4%, but only traces of sn-2 isomers of caproates were detected in butteroil. The ratio of sn-1(3)- to sn-2-butyrates and caproates in interesterified butteroil averaged 2.0:1. The most abundant molecular species of mono-short-chain TG in butteroil were BPP + BMS (5.6 mol%), BPO + BSPo (4.8 mol%), BMP + BLaS (3.4 mol%), BMO + BPPo (2.7 mol%), BPS (2.5 mol%), and CoPP + CoMS (2.3 mol%).