Tidsskrift : European Journal of Lipid Science and Technology , vol. 108 , p. 589–597 , 2006
Trykt : 1438-7697
Elektronisk : 1438-9312
Publikasjonstype : Vitenskapelig artikkel
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Concentrates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were heated at 140–240 °C for 2–8 h under nitrogen. The trans isomers were analysed by gas chromatography-mass spectrometry on a BPX-70 cyanopropyl column. All geometrical isomers of EPA and DHA with one trans double bond were observed. The rate constants (k) for the isomerisation of the all-cis isomers were calculated and found to be higher than previously reported for linoleic acid and α-linolenic acid. Arrhenius plots showed a linear relationship between ln k and the reciprocal absolute temperature above 180 °C. The distribution patterns of isomers with one trans double bond are approximately constant up to a degree of isomerisation of 25%. The degree of isomerisation can therefore be estimated from selected trans peaks.