Antioxidant dietary fibre recovery from Brazilian Pinot noir grape pomace

Brazilian grape pomace was extracted in hot water using a factorial design to evaluate polysaccharide recovery. Dependent variables were temperature, particle size and solute:solvent ratio. Polysaccharide yields varied from 3 to 10%, and the highest sugar content was observed when extraction was carried out at 100 °C, from fine particle sizes (≤249 μm), in a 1:12 solute:solvent ratio. Monosaccharide compositions of the flours afforded, in average, Rha,Ara,Xyl,Man,Gal,Glc,GalA in a 3:32:2:13:11:20:19 molar ratio, with varied Glc:GalA ratios. 13C NMR and HSQC spectra confirmed the presence of pectic and glucose-based polysaccharides in the extracts. Phenolic compounds were found after pomace extractions, and cathechin, gallic acid and epicatechin were the main identified compounds. Extracts also presented ABTS radical scavenging capacity (from 8.00 to 46.60 mMol Trolox/100g pomace), which means that these grape pomace flours are rich in antioxidant dietary fiber and have a potential use as food ingredients.