Abstract: A colorimetric method for the determination of the peroxide value (POV) of edible vegetable oils was established based on the peroxidase-like catalytic activity of Fe3O4@COOH nanoenzyme. For five edible vegetable oils (corn oil, peanut oil, sunflower oil, rapeseed oil, and soybean oil), POV over the range of 0–0.3 g/100 g exhibited a good linear relationship with absorbance values. The proposed method could accurately detect the POV of edible vegetable oils oxidized in three different ways (ultraviolet lamp irradiation, oven heating and natural oxidation). The differences between the POV determined by this method and the national standard method for 25 oil samples were less than 0.05, and the relative standard deviations (RSDs) for corn oil, peanut oil, sunflower oil, rapeseed oil, and soybean oil were 6.13 %, 5.84 %, 6.82 %, 3.62 % and 5.75 %, respectively, indicating good practicability of the colorimetric method. This study provides a fast and convenient method for determining the POV of edible pure vegetable oils.

Key words: Fe3O4@COOH nanozyme; edible vegetable oil; peroxide value; colorimetric detection