The FC assays were performed according to a modified method
of Gutfinger (1981). An appropriate volume of antioxidant solution
or wine dilution was dispensed into 2 ml microcentrifuge tubes
with the volume adjusted to 1400 ll with MilliQ water. Then,
300 ll of FC reagent (previously diluted 1:2 (v/v) with MilliQ
water) were added, and the samples were mixed. After 5 min,
300 ll of Na2CO3 (20%, w/v) were added, and the samples were
mixed again. The absorbance at 765 nm (A765) was measured after
a 90 min incubation at room temperature. As for the DPPH assay,
the AOPs of the model antioxidants were expressed as the molar
ratios of trolox/antioxidant, as determined from the calibration
curve for each antioxidant, comparing with the calibration curves
obtained with known concentrations of trolox. The AOPs of the
wines were expressed as TE (mM trolox equivalents in the wine).