2.8.2. Ferric Ion Reducing Antioxidant Power (FRAP)

The antioxidant power of dried aril was measured using the colourimetric method according to [30,32]. The FRAP working solution was freshly prepared in mixtures of 300 mM acetate buffer (50 mL), 10 mM 2,4,6-tripyridyl-s-triazine (TPTZ) (5 mL) and 20 mM ferric chloride (5 mL) at 37 ◦C. In triplicates, diluted aqueous methanolic dried aril extracts (0.15 mL) were added to 2.85 mL of the FRAP working solution followed by a 30 min incubation in the dark. By measuring the absorbance at 593 nm, the reduction of the Fe3<sup>+</sup>-TPTZ complex to a coloured Fe2<sup>+</sup>-TPTZ complex at low pH of dried aril extracts was monitored. Trolox (0–10 mM) was used for the calibration curve, and the results were expressed as Trolox (mM) equivalents per gram dry matter (mM TE/g DM).
