13C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition of some margarines |
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Authors: | Marcel S F Lie Ken Jie C C Lam Mohammed Khysar Pasha Kamen L Stefenov I Marekov |
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Affiliation: | (1) Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong;(2) Institute of Organic Chemistry, Bulgarian Academy of Sciences, 1040 Sofia, Bulgaria |
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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. |
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Keywords: | 13C NMR fatty acid composition margarine milk fat partially hydrogenated oils triacylglycerol triglyceride |
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