| Abstract
| - The oxidation of α-tocopherol (TH) in chilled and frozen fish muscle was determined using high-performance liquid chromatography−atmospheric pressure chemical ionization−mass spectrometry.TH oxidation byproducts were identified as α-tocopherolquinone (TQ), 5,6-epoxy-α-tocopherolquinone(TQE1), and 2-3-epoxy-α-tocopherolquinone (TQE2). The concentration of TH decreased significantlyduring storage while those of TQ, TQE1, and TQE2 increased noteworthy. The relative amounts ofTH and its oxidized products were significantly related with the extent of oxidation produced inpostmortem fish, and the ratio TQ/TH is suggested as an index of oxidative stress in fish muscle.The effect of phenolic antioxidants supplementation on retarding TH oxidation was also studied. Datasuggested that the addition of 100 ppm of caffeic acid, hydroxytyrosol, and propyl gallate couldregenerate endogenous TH from its oxidized forms resulting in an antioxidant synergy consistentwith the reduction of lipid oxidation observed in fish muscle supplemented with phenolic compounds. Keywords: α-Tocopherol; tocopherolquinones; oxidation; fish storage
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