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Abstract
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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.
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