No abstract

Lipid oxidation is a complex phenomenon involving free radicals which are highly reactive molecular species. The life-time of these radical species is extremely short and their detection is therefore difficult. Several electron spin resonance (ESR) spectroscopy methodologies make it possible to identify, quantify and measure the reactivity of radical species formed during oxidationreduction reactions. In this study we took advantage of the specificity of ESR spectroscopy to detect radical compounds in order to determine the rate constants of hydroperoxide degradation, a key reaction involved in lipid oxidation. The interaction of 5-doxyl stearic acid and lipidderived radicals was studied by following the intensity of ESR spectra. A kinetic model was developed to simulate data analysis obtained by ESR and values of rate constants for hydroperoxide degradation were determined at 100 and 110°C. This quantitative approach of ESR spectroscopy has produced useful information about new rate estimates for hydroperoxide degradation in edible oils.

Oxidative reactions that involve lipids are among the most important causes of deterioration of foods and affect both their shelf life and their organoleptic and nutritional properties. Radicals are intermediate key-constituents in these reactions. Their detection is therefore essential in order to understand and predict early stages of these destructive oxidations. Several Electron Spin Resonance (ESR) methodologies (direct and indirect) make it possible to identify, quantify and measure the reactivity of radical species formed during oxidative-reductive reactions. They are also used to evaluate the antiradical activity of antioxidants delaying lipid oxidation. An overview on the use of different ESR methodologies to study lipid oxidation in foods is reported in this paper.