Effect of hops oil on thermal oxidative stability of sunflower oil

In this study, the effect of hops oil on the thermal oxidative stability of sunflower oil was investigated. Within the scope of the study, 4 groups were used, as the control group sunflower oil (K), which does not contain any antioxidants, sunflower oil (B) containing 100 ppm BHT, sunflower oil (S1) containing 1200 ppm hops oil, and sunflower oil (S2) containing 2400 ppm hops oil. Heat treatment was applied to the oil samples for 5 minutes at 180°C for 10 times. The amount of free fatty acid, the number of peroxide, the value of p-anisidine, the amount of conjugated diene and conjugated triene, induction times were investigated in order to determine the level of oxidation and stability against the oxidation resulting from the effect of heat treatment. In order to determine the antioxidant activity change, DPPH (1,1-diphenyl-2-picrylhydrazil) radical scavenging power and β-carotene bleaching test were applied. In addition, the change in the fatty acid composition of the samples was investigated by gas chromatography. At the end of the applied heat treatments, it was observed that the hops oil added at the rate of 2400 ppm prevented the acidity increase significantly. Peroxide values decreased in all sample groups and varied between 2,84 meq O2/kg and 6,20 meq O2/kg. In the study, p-anisidine values increased and the highest values were found in the K (82,10) and S1 (74,96) groups. The amount of conjugated diene and conjugated triene increased in all sample groups, and K group was the most affected by oxidation. Oxidation caused by the effect of heat treatments affected the fatty acid composition of the samples, and the amount of palmitic acid, stearic acid and oleic acid in particular changed significantly. When the change in induction times was examined, B group (4,28 hours) and S2 group (4,22 hours) showed the best stability against thermooxidation. In the study, antioxidant activity values decreased in all sample groups with the increase in the number of heat treatments. When the heat treatments were completed, the highest antioxidant activity values were determined in the B group and S2 group. According to the data obtained at the end of the study, the best thermal oxidative stability was determined in the B group and S2 group samples. Oxidation caused by the effect of heat treatment significantly affected the K group oil samples without additives.