فاطمه شهدادی

Background: Nowadays, natural antioxidants are used to replace synthetic antioxidants for delaying or preventing the oxidation of edible oils. In this study, phenolic compounds and antioxidant properties of methanol extracts of Spirulina microalgae (Arthrospira platensis) were measured. Methods: Phenolic content was measured by Folin–Ciocalteau method and antioxidant activity was measured by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Also, spirulina microalgae as natural antioxidant, was added to sesame oil for improving its oxidative stability. The effects of methanol extract of these microalgae in four concentrations (0, 500, 1000 and 2000 ppm) and synthetic antioxidants of butylated hydroxyl anyzole (BHA) and butylated hydroxytoluene (BHT) in two levels (100 and 200 ppm) in retarding the sesame oil oxidation were examined. Results: The results showed that spirulina extract had 50.54 mg gallic acid/g samples total phenols and antiradical activity (84.38%). By increasing the concentration of the extracts, the oxidation process decreased. Methanol extract at 1000 ppm concentration had the highest antiradical activity than other concentrations and its antiradical activity was alike the synthesis antioxidant of BHA. By Increasing of storage period, peroxide values in 500 and 1000 ppm of spirulina extracts first increased then decreased and in other treatment increased. During storage time thiobarbituric acid index increased. However, this increase was higher in control treatment than others. Conclusion: According to the stated content, it can be said that methanol extracts of spirulina have appropriate antioxidant properties and spirulina can be used as a natural antioxidant to improve the oxidative stability of sesame oil.