Improvement of the Oxidative Stability of Virgin Olive Oil Using Spirulina as a Natural Antioxidant

Nowadays, natural antioxidants are used to replace synthetic antioxidants for delaying or preventing the oxidation of edible oils. In this study, microalgae Spirulina (Arthrospira platensis), as natural antioxidant, was added to virgin olive oil for improving its oxidative stability.

In the first stage, the antioxidant activity of Spirulina and the physico-chemical properties of virgin olive oil were evaluated. In the second stage, the effect of Spirulina addition on the oxidative stability of virgin olive oil was determined using active oxygen method (AOM). Three samples of virgin olive oil with 0.5% (w/w) Spirulina (as natural antioxidant), 0.01% (w/w) BHT (as synthetic antioxidant), and without any antioxidant (as control) were prepared. The mean of induction period, protection factor, and antioxidant activity were calculated. Statistical analysis was performed using SPSS 19 software.

The results showed that Spirulina has good total phenolic content (67.72 mg gallic acid eq/g sample), total flavonoid content (9.16 mg quercetin eq/g sample), IC50 value (0.364 mg/ml), and total antioxidant activity (17.98 mg Vit C/g sample). Induction period, protection factor, and antioxidant activity of the sample containing Spirulina (31.15 h, 1.37, and 0.42, respectively) were significantly higher than those of the control sample (22.85 h, 1, and 0.00, respectively) and less than those of the sample containing BHT (42.71 h, 1.87, and 1.00, respectively).

Due to the banned use of synthetic antioxidants in virgin olive oil and appropriate antioxidant activity of Spirulina, Spirulina as natural antioxidant can improve the oxidative stability of virgin olive oil.