Lipids

, Volume 33, Issue 7, pp 715–722

Effects of α- and γ-tocopherols on the autooxidation of purified sunflower triacylglycerols

Authors

  • Maria Dolores Fuster
    • Departamento de Biologia Vegetal (Fisiologia Vegetal), Facultad de Biologia, Campus de EspinardoUniversidad de Murcia
  • Anna-Maija Lampi
    • Department of Applied Chemistry & MicrobiologyUniversity of Helsinki
  • Anu Hopia
    • Department of Applied Chemistry & MicrobiologyUniversity of Helsinki
    • Department of Food ScienceSLU
Article

DOI: 10.1007/s11745-998-0261-3

Cite this article as:
Fuster, M.D., Lampi, A., Hopia, A. et al. Lipids (1998) 33: 715. doi:10.1007/s11745-998-0261-3
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Abstract

The antioxidant effects of α- and γ-tocopherols were evaluated in a model system based on the autooxidation of purified sunflower oil (p-SFO) triacylglycerols at 55°C for 7 d. Both tocopherols were found to cause more than 90% reduction in peroxide value when present at concentrations >20 ppm. α-Tocopherol was a better antioxidant than γ-tocopherol at concentrations ≤40 ppm but a worse antioxidant at concentrations >200 ppm. Neither α- nor γ-tocopherol showed a prooxidant effect at concentrations as high as 2000 ppm. The amount of tocopherols consumed during the course of oxidation was positively correlated to the initial concentration of tocopherols, and the correlation was stronger for α- than for γ-tocopherol. This correlation suggested that, besides reactions with peroxyl radicals, destruction of tocopherols may be attributed to unknown side reactions. Addition of FeSO4, as a prooxidant, caused a 12% increase in the peroxide value of p-SFO in the absence of tocopherols. When tocopherols were added together with FeSO4, some increase in peroxide value was observed for samples containing 200, 600 or 1000 ppm of α- but not γ-tocopherol. The addition of FeSO4, however, caused an increase in the amount of α- and γ-tocopherols destroyed and led to stronger positive correlations between the amount of tocopherols destroyed during oxidation and initial concentration of tocopherols. No synergistic or antagonistic interaction was observed when α- and γ-tocopherols were added together to autooxidizing p-SFO.

Abbreviations

BHT

butylated hydroxytoluene

HOSO

high-oleic sunflower oil

HPLC

high-performance liquid chromatography

HPSEC

high-performance size exclusive chromatography

PF

protection factor

p-HOSO

purified high-oleic sunflower oil

p-RSO

purified rapeseed oil

p-SFO

purified sunflower oil

PUFA

polyunsaturated fatty acids

PV

peroxide value

RSO

rapeseed oil

SFO

sunflower oil

TO

tocopheroxyl radical

Copyright information

© AOCS Press 1998