RESEARCH ARTICLE


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



Ioannis G. Roussis*, 1, Despina Papadopoulou1, Maria Sakarellos-Daitsiotis2
1 Laboratory of Food Chemistry
2 Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece


© 2009 Roussis et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Laboratory of Food Chemistry; 2Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece; Tel: ++30 26510 98344; Fax: ++30 26510 98782; E-mail: iroussis@uoi.gr


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 50oC, 120oC and 180oC was evaluated. The bsorbances 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 120oC) or similar (180oC) 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.

Keywords: N-acetyl-cysteine, glutathione, thiols, oxidation, oil.