COMPOSITION OF THE TRIACYLGLYCEROLS OF BUTTERFAT AND ITS FRACTIONS OBTAINED BY AN INDUSTRIAL MELT CRYSTALLIZATION PROCESS

The compositions of two solid and two liquid fractions of butterfat obtained by the Tirtiaux melt fractionation process were studied. The triacylglycerols of each of the four fractions and butterfat were separated by silver ion high-performance liquid chromatography (Ag-HPLC) into six subfractions. Each was analyzed for fatty acid composition by gas chromatography and was separated by reversed-phase HPLC. The liquid Tirtiaux fractions contained higher proportions of saturated short-chain and monoenoic fatty acids, especially cis-18:1, than the solid ones. Every Tirtiaux fraction comprised at least 64 % saturated fatty acids. The trisaturated (35.0-58.9 %) and disaturated cis-monoenoic (27.9-44.1 %) triacylglycerols were the most abundant Ag-HPLC fractions, together representing at least 79 %. The other unsaturated fractions were composed of disaturated trans-monoenoic (2.5-3.4 %), saturated cis,trans-dimonoenoic (1.8-4.4 %), saturated cis,cis-dimonoenoic (5.2-9.1 %), and the more unsaturated molecules (2.8-5.0 %). The greatest differences between the Tirtiaux fractions were found in the trisaturated triacylglycerols. There were differences too, albeit less pronounced, in the disaturated cis- and disaturated trans-monoenoic molecules. Although the di- and polyunsaturated molecules were not evenly distributed between the solid and liquid Tirtiaux fractions, no clear selectivity according to their triacylglycerol structure was observed.