DETERMINATION OF THE POSITIONAL DISTRIBUTION OF FATTY-ACIDS IN BUTTERFAT TRIACYLGLYCEROLS

Triacylglycerol (TAG) standards were separated by analytical high-performance liquid chromatography (HPLC) with laser light-scattering detection (LLSD). A high sensitivity for TAGs was observed with LLSD whereas poor sensitivity was observed with ultraviolet detection. The HPLC-LLSD analytical separation of butterfat TAGs showed that the TAGs were eluted according to increasing carbon number. Preparative HPLC-LLSD was used to characterize butterfat TAGs that contained hypercholesterolemic fatty acids (laurate, myristate, palmitate) with carbon chainlengths of 12 or greater. These TAG fractions accounted for 29.2% of the total butterfat TAGs. Analysis of the positional distribution of fatty acids of selected butterfat TAGs containing hypercholesterolemic fatty acids showed the presence of positional isomers in each of these fractions. These butterfat TAGs also showed the predominant presence of hypercholesterolemic fatty acids at the sn-2 position. The characterization of the positional distribution of hypercholesterolemic fatty acids in butterfat TAGs is the first step for the determination of the metabolic role of the positional distribution in the hypercholesterolemic effects of butter.