Antioxidant activity of sage extracts in rapeseed oil irradiated with UV-rays

The antioxidant activities of sage acetone oleoresin and its methanol-water fractions were tested in rapeseed oil at 0.1% concentrations and 80 degree sC temperature after irradiation with UV-rays (exposition 0.5 h). It was de termined that even little doses of UV irradiation induce oxidation process in rapeseed oil samples both with additives and without them. The antioxida nt activity of a synthetic antioxidant BHT was much lower than that of the sage fractions at 80 degreesC and forced air oven conditions. This finding proves the advantage of sage extracts in comparison with BHT at high temper atures. It was also found that methanol-water fraction separated from aceto ne oleoresin had the highest antioxidant activity in terms of the formation of primary and secondary oxidation products. Oil sample with this additive had the highest protection factor (PF = 4.53) when the oil was not irradia ted with UV rays. The data obtained showed that all sage extracts had very strong antioxidant activity (PF > 3).