The effect of different natural antioxidant materials on the oxidative stability of frying oil

In this study, the frying process done 4 times a day for 3 days in the fryer at 180 ˚C was applied to commercial frying oil, hazelnut oil, palm olein oil, oil obtained by blending different proportions of hazelnut oil with palm olein oil (blend 1 and blend 2). Some chemical and physical analyzes were carried out to determine how the oils used in the frying process were effected by the process. These analyzes are free acidity (%0.35 - %1.39), peroxide number (0.64-11.49 meqO2/kg), p-anisidine value (5.06-67.52), total oxidation value (7.66-91.11), conjugated diene (2.84-11.09) and triene (1.07-5.65), color analysis, total polar material, viscosity (17.64–140 mPa.s) analysis. In addition, in order to increase the oxidative stability of oils. BHT (200 ppm), the rhubarb plant extract (Rheum ribes L.), the quinoa plant extract (Chenopodium quinoa Willd.), propolis extracts (1000-1500 ppm) that, all determined by preliminary studies were added in oil samples. The effects of natural extracts were compared with BHT and it was found that propolis extract at 1500 ppm level had the closest effect to BHT. According to analysis results, it was seen that the physical and chemical properties of oil samples changed significantly with increasing frying number and this change was statistically significant (p <0.05). Furthermore, fatty acid profile, volatile components and 3-MCPD (1.44-9.11 ppm) and glycidyl (0.36-13.03 ppm) esters were examined in all oil samples. According to the results of the study, it was found that the oxidative stability increased with the rising of palm olein oil. However we can say that, it was also effective in the formation of higher amounts of 3-MCPD and glycidyl ester.