Positional distribution of fatty acids in the triglyceride classes of milk fat

A sample of milk fat was fractionated into high, medium and low molecular weight triglycerides by silicic acid column chromatography. Each fraction was further separated by silver ion adsorption thin-layer chromatography into triglyceride class which were subjected to stereospecific analysis. Trans-monoene fatty acids were incorporated into triglycerides in the same manner as their cis-isomer. The specific positional distribution for fatty acids in intact mild fat triglycerides was not always maintained in the molecular weight fractions or in the various classes of unsaturation. The significance of these findings is discussed in relation to biosynthetic mechanisms for milk fat synthesis.