Characterization of phenolics, in vitro reducing capacity and anti-glycation activity of red grape skins recovered from winemaking by-products

Variability was observed in total phenolics (12.1-53.6 g gallic acid Eq/kg), proanthocyanidins (7.2-51.1 g/kg), anthocyanins (2.5-13.8 g malvidin 3-O glucoside Eq/kg), flavonols (0.3-2.6 g quercetin 3-O glucoside Eq/kg) and reducing capacity (103-511 mmol Fe(II) Eq/kg). For all samples, the anti-glycation effectiveness was higher than that of commercial nutraceutical preparations. Hence, in spite of differences in cultivar, location of the vineyard and winemaking procedures, these by-products could be used as a source of cost-effective anti-glycation agent either as a food ingredient or as a nutraceutical preparation.