In this study, water and chelator-soluble pectic polysaccharide fractions were obtained from white grape skins, aiming to study their impact on the interaction between low polymerized grape seed procyanidins and salivary proteins. Water and chelator-soluble polysaccharide fractions were composed by uronic acids and neutral sugars, mainly arabinose and galactose, with water polysaccharide fraction showing a higher amount of branched pectic polysaccharides. Both polysaccharide fractions were able to mitigate salivary protein-procyanidin interactions, by a competition mechanism, resulting in a decrease of the amount of precipitated protein. Water polysaccharide fraction was the most effective in inhibiting salivary protein precipitation, especially for acidic proline-rich proteins, due to the higher affinity to interact with procyanidins (KA = 22222 M-1 and KA = 365 M-1 for water and chelator polysaccharides, respectively). The interaction between polysaccharides and procyanidins showed to be mainly governed by hydrophobic effect.
Keywords: Astringency; Pectin; Procyanidins; Salivary proteins.
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