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

• Published in: Journal of the American Oil Chemists' Society Vol. 87; no. 12; pp. 1425 - 1433
• Main Authors: Suárez, Erick Reyes, Mugford, Paul F., Rolle, Alfred J., Burton, Ian W., Walter, John A., Kralovec, Jaroslav A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-12-2010; Springe-Verlag; Springer
• Subjects: 13C NMR; Agriculture; Anchovy; Biological and medical sciences; Biomaterials; Biotechnology; Chemistry; Chemistry and Materials Science; DHA; EPA; Fat industries; Fish and seafood industries; Fish oil concentrate; Food industries; Food Science; Fundamental and applied biological sciences. Psychology; Industrial Chemistry/Chemical Engineering; Original Paper; Regioselectivity; Regio‐isomeric distribution; Sardine; Triacylglycerol; Sardine; Fish oil concentrate; Regioselectivity; Triacylglycerol; EPA; C NMR; Regio-isomeric distribution; DHA; Anchovy; Edible fish; Lipids; Edible oil; Fish oil; Oils and fats industry; Distribution; Concentrate
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-010-1638-2

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
13
C 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.
13
C-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.