Antioxidant activities of α- and γ-tocopherols in the oxidation of rapeseed oil triacylglycerols
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Antioxidant properties of 5 to 500 µg/g levels of α-and γ-tocopherols, in the oxidation of rapeseed oil triacylglycerols (RO TAG), were studied at 40°C in the dark. Each tocopherol alone and in a mixture was studied for its stability in oxidizing RO TAG. Also the effects of tocopherols on the formation of primary and secondary oxidation products of RO TAG were investigated. Both tocopherols significantly retarded the oxidation of RO TAG. At low levels (≤50 µg/g), α-tocopherol was more stable and was a more effective antioxidant than γ-tocopherol. At higher α-tocopherol levels (>100 µg/g), there was a relative increase in hydroperoxide formation parallel to consumption of α-tocopherol, which was not found with γ-tocopherol. Therefore, γ-tocopherol was a more effective antioxidant than α-tocopherol at levels above 100 µg/g. As long as there were tocopherols present, the hydroperoxides were quite stable and no volatile aldehydes were formed. In a mixture, α-tocopherol protected γ-tocopherol from being oxidized at the addition levels of 5+5 and 10+10 µg/g but no synergism between the tocopherols was found. α-Tocopherol was less stable in the 500+500 µg/g mixture than when added alone to the RO TAG. No prooxidant activity of either tocopherol or their mixture was found.
Key WordsAntioxidant rapeseed oil triacylglycerols α-tocopherol γ-tocopherol
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- 3.Cillard, J., P. Cillard, and M. Cormier, Effect of Experimental Factors on the Prooxidant Behavior of α-Tocopherol, J. Am. Oil Chem. Soc. 57:255–261 (1980).Google Scholar
- 7.Warner, K., Measurement of Tocopherol Efficacy in Fats and Oils, in Antioxidant Methodology in vivo and in vitro Concepts, edited by O.I. Aruoma and S.L. Cuppett, AOCS Press, Champaign, 1997, pp. 223–233.Google Scholar
- 8.Yanishlieva, N.V., and E.M. Marinova, Inhibited Oxidation of Lipids I: Complex Estimation and Comparison of the Antioxidative Properties of Some Natural and Synthetic Antioxidants, Fat Sci. Technol. 94:374–379 (1992).Google Scholar
- 14.Lampi, A.M., A. Hopia, P. Ekholm, and V. Piironen, Method for the Preparation of Triacylglycerol Fractions from Rapeseed and Other Oils for Autoxidation Studies, Food Sci. Technol. 25:386–388 (1992).Google Scholar
- 16.Shantha, N.C., and E.A. Decker, Rapid, Sensitive, Iron-Based Spectrophotometric Methods for Determination of Peroxide Values of Food Lipids, J. AOAC Int. 77:421–424 (1994).Google Scholar
- 17.Official method AOCS Cd 18–90, p-Anisidine Value, in Official Methods and Recommended Practices of the American Oil Chemists’ Society, 4th edn., American Oil Chemists’ Society, Champaign, 1990.Google Scholar
- 25.Gottstein, T., and W. Grosch, Model Study of Different Antioxidant Properties of α- and γ-Tocopherol in Fats, Fat Sci. Technol. 92:139–144 (1990).Google Scholar
- 26.Pongracz, G., H. Weiser, and D. Matzinger, Tocopherole—Antioxidantien der Natur, Fat Sci. Technol. 97:90–104 (1995).Google Scholar
- 30.Park, D.K., J. Terao, and S. Matsushita, The Isomeric Composition of Hydroperoxides Formed by Autoxidation of Unsaturated Triglycerides and Vegetable Oils, Agric. Biol. Chem. 45:2071–2076 (1981).Google Scholar
- 31.Grosch, W., Reaction of Hydroperoxides—Products of Low Molecular Weight, in Autoxidation of Unsaturated Lipids. Food Science and Technology. A Series of Monographs, edited by H.W.S. Chan, Academic Press, London, 1978.Google Scholar