Combination of Gas Chromatography-Mass Spectrometry and Electron Spin Resonance Spectroscopy for Analysis of Oxidative Stability in Soybean Oil During Deep-Frying Process

Lipid oxidation of edible oil during frying process is a complex process and involves free radical chain reactions. Soybean oil with high amount of unsaturated fatty acids was used to investigate the impact of frying time on oxidative stability of oil. Electron spin resonance (ESR) spectroscopy technique was applied to identify and quantify the formed radicals, along with the assessment of physicochemical parameters including peroxide value, oxidative stability, fatty acid composition, and volatile profile. Results showed that the amount of formed free radicals determined by ESR in frying oil increased with the prolongation of frying time. The availability of this method was compared with physicochemical properties and the well correlation coefficients were obtained. Besides, main volatile aldehyde compounds produced by β-scission homolytic cleavage of peroxide group in frying oil during thermal oxidation were derived from oxidation of oleic and linoleic acid.