Evaluation of antioxidant activity of broccoli (Brassica oleracea) sprout extract on oxidative stability of soybean oil under accelerated storage at 60°C

In order to increase the oxidative stability of oil, various antioxidants are used. The use of synthetic antioxidants causes concern for the health of consumers due to their carcinogenicity, so today the food industry seeks to use natural alternatives instead of synthetic types to improve the oxidative shelf life of oils. Therefore, the aim of this research was to investigate the possibility of using broccoli sprouts extract (BSE) as a natural antioxidant to develop the oxidative stability of soybean oil. Different levels of BSE, including 200, 400, and 800 ppm, were added to soybean oil and these samples were compared with samples without antioxidants (control) and sample containing TBHQ synthetic antioxidants (100 ppm). Different tests including acid, peroxide, anisidine, totox, thiobarbituric acid (TBA) indexes, and Rancimat number were performed on the oil samples during the accelerated storage period of 18 days at a temperature of 60 °C. The obtained results showed that during the storage period, the values of acid, peroxide, anisidine, totox, and TBA indexes of oil samples increased and the Rancimat number decreased significantly (p<0.05), however, the rate of these changes in the control sample was significantly higher than other samples. Adding BSE and increasing its concentration in the samples significantly reduced the rate of lipid oxidation and triglycerides decomposition in oils (p<0.05), and the highest oxidative stability was observed in the sample containing 800 ppm of BSE. This level of the BSE showed even higher antioxidant activity than the TBHQ synthetic antioxidant. Finally, the results of this study indicated the antioxidant activity of BSE in soybean oil, and therefore, this extract at the level of 800 ppm can be used as a natural antioxidant to develop the oxidative shelf life and stability of soybean oil.