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. Mixedsn‐1,2(2,3)‐ andX‐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 enantiomericsn‐1,2‐andsn‐2,3‐diacylglycerols and theX‐1,3‐diacylglycerols as their 3,5‐dinitrophenylurethanes were resolved by HPLC on chiral columns. Both acetic and butyric acids were exclusively associated with thesn‐ 2,3‐ andX‐1,3‐diacylglycerols of short and long chainlength. These results establish the presence of acetic and butyric acids in thesn‐3‐position of bovine milk fat triacylglycerols. Other short‐and medium‐chainlength acids were found in progressively increasing proportions also in thesn‐1‐ andsn‐2‐positions.