The change in antioxidant activity after frying was also dependent on the nature of the oil. In one study it was found that after 50 minutes of frying in hazelnut oil and corn oil, the antioxidant activity was significantly reduced. However, it took 75 and 25 minutes of frying to register a significant decrease in the antioxidant activity of soybean oil and olive oil respectively . However, this study used the DPPH assay to measure antioxidant activity and it is known that oxidation products can contribute positively to this assy . Due to the high PUFA content soybean oil is expected to generate more oxidation products. This may be the reason why the DPPH inhibition activity of soybean oil decreases more slowly.