¹³C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition of some margarines

Abstract

The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona” (Holland), were studied by¹³C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate. There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of “Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique.