DETERMINATION OF POSITIONAL DISTRIBUTION OF SHORT-CHAIN FATTY-ACIDS IN BOVINE-MILK FAT ON CHIRAL COLUMNS

The positional distribution of acetic and butyric acids in bovine milk fat triacylglycerols was determined by chiral-phase high-performance liquid chromatography (HPLC) of the derived diacylglycerols. Enriched fractions of acetic and butyric acid-containing triacylglycerols were isolated by normal phase thin-layer chromatography (TLC) from a molecular distillate of butter oil, and they were fully hydrogenated. Mixed sn-1,2(2,3)- and X-1,3-diacylglycerols of short- and long-chainlength, which were generated by partial Grignard degradation of the hydrogenated triacylglycerols, were isolated by borate-TLC. The enantiomeric sn 1,2- and sn-2,3-diacylglycerols and the X-1,3-diacylglycerols as their 3,5-dinitrophenylurethanes were resolved by HPLC on chiral columns. Both acetic and butyric acids were exclusively associated with the sn-2,3- and X-1,3-diacylglycerols of short and long chainlength. These results establish the presence of acetic and butyric acids in the sn-3-position of bovine milk fat triacylglycerols. Other short- and medium-chainlength acids were found in progressively increasing proportions also in the sn-1- and sn-2-positions.