AND SUMMARYAn analytical approach is presented for the study of one-phase interesterification of mixtures of sunflowerseed oil with fully hydrogenated lard, natural lard, and tallow, based on triglyceride group analysis by argentation thin layer chromatography. The curves for the changes of each of ten triglyceride groups, differing in unsaturation, are reported. These are used to establish the conversion of the initial composition to the random limits in the mixtures cited. The alterations in the differential dilatation curves are explained in part by the changes in the triglyceride composition.