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13C-NMR Regioisomeric Analysis of EPA and DHA in Fish Oil Derived Triacylglycerol Concentrates

Journal of the American Oil Chemists' Society

Abstract

The regio-isomeric distribution of the omega-3 polyunsaturated fatty acids (PUFA) cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in the triacylglycerols (TAG) of anchovy/sardine fish oil was determined by 13C nuclear magnetic resonance (NMR) analysis under quantitative conditions. From the measurements of sn-1,3 and sn-2 carbonyl peak areas it was established that EPA was mainly located in the sn-1,3 positions, whereas DHA primarily occupied the sn-2 position. Reconstituted TAG prepared by Candida antarctica lipase-B (CALB) glycerolysis of the ethyl ester (EE) or the free fatty acid (FFA) forms of anchovy/sardine fish oil, displayed a different pattern: EPA was equally distributed, while DHA was preferentially attached to the sn-1,3 positions. TAG concentrates of varying EPA and DHA molar fractions were prepared by CALB-catalyzed glycerolysis of the corresponding EE and FFA. 13C-NMR analysis of the purified products revealed a lack of CALB regioselectivity for EPA and a slight sn-1,3 regioselectivity for DHA. Since this pattern was observed in all cases of this study, it was concluded that the lipase regioselectivity during TAG synthesis is independent of both the acyl donor type (carboxylic acid or ester) and the fatty acid content of the oil substrate.

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Acknowledgments

This work has been supported by the Industrial Research Assistance Program of the National Research Council of Canada (Project# 674301). We thank Rae Townsley for excellent technical assistance.

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Correspondence to Jaroslav A. Kralovec.

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Suárez, E.R., Mugford, P.F., Rolle, A.J. et al. 13C-NMR Regioisomeric Analysis of EPA and DHA in Fish Oil Derived Triacylglycerol Concentrates. J Am Oil Chem Soc 87, 1425–1433 (2010). https://doi.org/10.1007/s11746-010-1638-2

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  • DOI: https://doi.org/10.1007/s11746-010-1638-2

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