The Open Food Science Journal

2009, 3 : 103-107
Published online 2009 December 24. DOI: 10.2174/18742564009030100103
Publisher ID: TOFSJ-3-103

Inhibition of the Oxidation of Corn Oil Stripped of Tocopherols and Refined Olive Oil by Thiols

Ioannis G. Roussis , Despina Papadopoulou and Maria Sakarellos-Daitsiotis
Laboratory of Food Chemistry; 2Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.

ABSTRACT

The ability of N-acetyl-cysteine and glutathione to inhibit the oxidation of corn oil stripped of tocopherols and refined olive oil was examined.

The oxidative stability of corn oil stripped of tocopherols at 50 oC, 120 oC and 180 oC was evaluated. The absorbances at 234 nm and 270 nm, and p-anisidine value were monitored. N-acetyl-cysteine and glutathione inhibited the oxidation of oil, N-acetyl-cysteine at a higher degree. In comparison to BHA at 200 mg/L, both thiols at 20-40 mg/L exhibited lower (50 oC and 120 oC) or similar (180 oC) antioxidant activities. Compounds similar to the two thiols but not containing –SH group, N-acetyl-serine and oxidized glutathione, exhibited very low or no antioxidant activities. The oxidative stability of refined olive oil at 20 oC was determined by monitoring the peroxide value. N-acetyl-cysteine and glutathione at 20 mg/L exhibited antioxidant activities comparable to that of BHA at 200 mg/L.

Present results show the ability of N-acetyl-cysteine and glutathione to inhibit the oxidation of corn oil stripped of tocopherols and refined olive oil indicating that thiols can inhibit the oxidation of any oil.