[Evaluation of antiradical activity of Malva sylvestris extract and its application in oil system]

ABSTRACT

Because of some adverse effect of chemical food additives such as synthetic antioxidants, it has been considered by researchers to replacing these materials by natural products. To measure the total phenolic content of Malva sylvestris extract [MSE]; to evaluate the antiradical activity of this extract by DPPH°, ABTS°+ and beta-carotene bleaching methods [BCB] and to study its application as natural antioxidant in soybean oil. Total phenolic content [TPC] of MSE was determined by Folin- Ciocalteau method. Antiradical activity was measured by DPPH°, ABTS°+ and BCB methods and compared with synthetic antioxidant BHA. The antioxidant activity of extract was studied in soybean oil [oven test at 70°C] by measuring peroxide value [PV], thiobarbituric acid value [TBA] and conjugated diene [CD] and compared with BHA and BHT [at two level 100 and 200 ppm]. MSE was possess 4.5% phenolic compounds in base of dry matter. In DPPH° assay, EC50 of MSE was 0.37 +/- 0.01 mg/ml. In ABTS°+ assay, maximum antioxidant activity was related to 5 mg/ml concentration of MSE [70% inhibition]. In BCB test, maximum antioxidant activity of 0.05 - 10 mg/ml concentration of MSE was related to its 10 mg/ml concentration of it [52.6%]. This extract could retard oxidation process of soybean oil at 400 ppm that was almost equal to BHA at 100 ppm. MSE showed antiradical activity and it seems it can be applied as natural antioxidant in foods containing edible oils