Detection of radical development by ESR spectroscopy techniques for assessment of oxidative susceptibility of fish oils

• Published in: European food research & technology Vol. 221; no. 5; pp. 667 - 674
• Main Authors: Falch, E, Velasco, J, Aursand, M, Andersen, M.L
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.10.2005; Berlin Springer Nature B.V
• Subjects: Biological and medical sciences; cod liver oil; docosahexaenoic acid; electron paramagnetic resonance spectroscopy; Fat industries; Fatty acids; Fish oils; food analysis; Food industries; food quality; free radicals; Fundamental and applied biological sciences. Psychology; General aspects; light intensity; lipid peroxidation; Methods of analysis, processing and quality control, regulation, standards; Oxidation; oxidative stability; peroxide value; Polyunsaturated fatty acids; reaction kinetics; Salmon; salmon oil; Spectroscopy; Spectrum analysis; temperature; thiobarbituric acid-reactive substances; Trapping; ESR; EPR spectrometry; Lipids; Edible oil; Fish oil; Spin trapping; Marine oils; Analysis method; Spin scavenging; Lipid oxidation; Development; Control method; Oxidation; Detection
• ISSN: 1438-2377; 1438-2385
• DOI: 10.1007/s00217-005-0009-y

Detection of radical development by two different Electron Spin Resonance (ESR) spectroscopy techniques has been evaluated for obtaining objective analytical information about oxidative susceptibility of fish oils under mild oxidation conditions. Two oils from different by-products in the fish industry, salmon viscera oil (SVO) and cod liver oil (CLO), were used. In addition, radical formation in the ethyl ester of docosahexaenoic acid (DHA) was studied as representing polyunsaturated fatty acids in fish oils that are very prone to oxidation. The ESR spin trapping technique, using the spin trap α-phenyl-N-tert-butylnitrone, and the ESR spin scavenging technique, using the stable nitroxyl radical 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO) to be scavenged by radicals generated in the oxidative process, were applied to detect radical development at 40 °C in the dark. For comparative purposes, oxidative susceptibility was evaluated by determination of peroxide value (PV) and the TBARS test under the same oxidation conditions. Results were also compared to the oil stability index (OSI) obtained at 60 °C. Results obtained by ESR spin trapping were consistent with results obtained in the OSI test, as well as those obtained for PV and the TBARS test. Therefore, detection of radical formation by ESR spin trapping provided objective information upon the relative oxidative susceptibility of SVO and CLO. On the other hand, results obtained by ESR spin scavenging were not concluding to establish the different oxidative susceptibility of the two oils found by the other determinations applied. The kinetic curves of TEMPO were similar for both oils, which suggests that mechanisms other than that based on the expected radical-radical interactions might be involved.