C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPIC ANALYSIS OF THE TRIACYLGLYCEROL COMPOSITION OF SOME MARGARINES

The triacylglycerol fraction of three samples of margarine, namely ''F lora'' (Holland), ''Kaliakra'' (Bulgaria), and ''Corona'' (Holland), w ere studied by C-13 nuclear magnetic resonance spectroscopy. By examin ing the various carbon chemi cal shifts of the saturated and unsaturat ed carbon nuclei, ''Flora'' margarine was shown to contain a mixture o f hydrogenated and unhydrogenated vegetable oils. This technique allow ed all major acyl groups (saturated, oleate, linoleate, and linolenate ) and minor acyl components [different positional isomers of long-chai n (E)- and (Z)-monoenoic moieties arising as by-products during cataly tic hydrogenation] to be identified. The amount of each fatty acid pre sent in the margarine was also estimated from the relative intensities of the corresponding signals. ''Kaliakra'' margarine consisted of a b lend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate. There were no signs in the spectru m of ''Kaliakra'' of any (E)-isomers, nor signals associated with posi tional 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 b utter in this sample was identified by the characteristic carbon shift s 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 te chnique.