FRAP assay
The FRAP assay directly determines the capacity of antioxidant compounds to reduce a ferric tripyridyltriazine complex to the ferrous form at low pH (Frankel and Meyer, 2000). Blue colour results from this reaction, which is spectrophotometrically measured t 593 nm. The absorbance is linearly related to the total reducing capacity of electron-donating antioxidants. According to Frankel and Meyer (2000) the main disadvantage of this approach is that the measured reducing capacity does not necessarily imply antioxidant activity. This method does not include a substrate prone to oxidation, hence no information is provided on the protective propertiesofantioxidants.