Evaluation the effect of green pea pod extract on oxidative stability of sunflower oil under accelerated conditions

Lipid oxidation is one of the most important reasons for decrease in nutritional quality and organoleptic properties of foods as well as the development and progression of various diseases through the formation of free radicals. Hence, the use of antioxidant compounds to protect foods against oxidation is essential. Nowadays, extensive studies were carried out on exploration of natural and safe antioxidant compounds due to consumers concerns about safety of synthetic ones. Therefore, in this study, the protective ability of green pea pod extract as a plant antiradical agent against oxidation of sunflower oil was investigated. At first, green pea pod extract was obtained using water, ethanol, acetone and hexane. Total phenolic content (TPC) and antiradical activities of extracts were assessed using colorimetry method, and DPPH and H2O2 radical scavenging activity test, respectively. Then, effect of green pea pod extract containing the highest amount of total phenolics and maximum antiradical ability on oxidative stability of sunflower oil under accelerated conditions at 65 ºC for 24 days were evaluated through peroxide, p-anisidine and TOTOX values. For this purpose, green pea pod extract at five different concentrations (200, 400, 600, 800 and 1000 ppm) and the synthetic antioxidant of BHT (200 ppm) were added to sunflower oil. The highest TPC (140.4 mgGAE/g) and DPPH and H2O2 radicals scavenging activity (82.47 and 10.63%, respectively) was obtained for ethanolic bioactive extract from green pea pod. For control sample, the maximum values of peroxide, p-anisidine and TOTOX were 185 meq O2/kg oil, 37 and 407 after 24 days under accelerated conditions. While these values were 128.2 meq O2/kg oil, 28 and 208 for the oil containing the lowest concentration of green pea pod ethanolic extract. The results revealed that addition of green pea pod ethanolic extract at a concentration of 1000 ppm in sunflower oil was more effective than BHT (200 ppm). The results obtained confirmed the suitability of green pea pod bioactive compounds antiradical activity especially for ethanolic extract. On the other hand, stability of sunflower oil seems to be difficult due to the high amount of linoleic acid but the results revealed that ethanolic extract of green pea pod was able to protect sunflower oil against oxidation as well. As a result, green pea pod ethanolic extract could be suggested as a natural and effective alternative for BHT in order to increase oxidative stability of sunflower oil.