Development of a chemiluminescent method for the evaluation of total hydroperoxide content of edible oils

Abstract

One of the most important quality indices of edible oils is the total hydroperoxide content expressed as peroxide value (PV). Oils with high hydroperoxide content show a degree of oxidation and, hence, lower quality. For these reasons, the development of methods for the evaluation of this quality index of edible oils is required.The aim of the present work is to develop, a rapid, accurate, sensitive, simple and low cost chemiluminescence (CL) method for the determination of the total hydroperoxide content of different kinds of olive oils and other types of edible oils. The CL method proposed is based on the chemiluminescent reaction of alkaline luminol and the hydroperoxides of oil, catalyzed by Fe(III) using 1-propanol as the reaction solvent. Calibration curves of the CL intensity as a function of concentration of di-tert-butyl peroxide, used as an external peroxide standard, and of different types of edible oils were prepared. In all the cases the correlation coefficient (R) of the regression lines was satisfactory (R>0.996). The precision of the method expressed in terms of repeatability and reproducibility was also satisfactory, as repeatability in terms of mean %RSD was 4.8% and reproducibility in terms of mean %RSD was 8%. The method was applied for the evaluation of total hydroperoxide content of olive oils, corn oils, sunflower oils, sesame oils and soybean oils, within the concentration range of 0.1–9.0%v/v and the obtained results were compared with those of the official method for peroxide value. Finally, the different types of olive oils and seed oils have been classified according to their estimated total hydroperoxide content.