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The influence of chemical composition on peroxidation kinetics of palm and nut oils

Authors : Temel kan Bak r


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Abstract

In this study, the fatty-acid content of peanut, hazelnut, coconut and palm oils were determined by gas chromatography (GSMS), and correlated to the kinetics of lipid oxidation. The peroxidation of oil emulsions was performed at in a ventilated incubation environment at 37ÂșC and pH 7. Primary products (hydroperoxides) and the secondary products (malondialdehyde) were monitored by ferric thiocyanate method (Fe(III) SCN) and thiobarbituric acid reactive substances (TBARS) analytical methods, respectively. Pseudo-first order kinetics of hydroperoxides and aldehydes were observed in copper-catalysed oil emulsions, and the absorbance values obtained as a function of the incubation period resulted in sigmoidal curves. The rate constants found via Fe(III) SCN method were calculated to be in the following descending order: peanut oil > hazelnut oil > palm oil > coconut oil, whereas that via TBARS method yielded peanut oil > hazelnut oil > coconut oil > palm oil. This study showed that the fatty acid content and peroxidation kinetics data can be used together in the selection of more nutritious fats with a longer shelf life.

Keyword

Ferric thiocyanate method, palm oil, hazelnut oil, lipid peroxidation, fatty acids