DETERMINATION OF HYDROPEROXIDES IN EDIBLE OILS BY ELECTRON-SPIN-RESONANCE, THIOBARBITURIC ACID ASSAY, AND LIQUID-CHROMATOGRAPHY CHEMILUMINESCENCE TECHNIQUES

The increasing concern over the possible relationship between lipid peroxidation and certain ailments, and correspondingly with food processing and storage, has prompted our examination of various techniques for the determination of hydroperoxides formed during lipid oxidation. A reversed-phase liquid chromatography method was used to separate the hydroperoxides, followed by postcolumn chemiluminescence detection. In addition, we compared these results with those obtained by the conventional thiobarbituric acid assay and a new procedure involving the oxidation of 2,2,6,6-tetramethyl-4-piperidone to nitroxides in the presence of hydroperoxides, followed by electron spin resonance spectroscopy. The formation and decay of hydroperoxides of methyl linoleate and corn oil under constant heating and oxygen purging are described.