RT Journal Article
SR Electronic
T1 Charge Properties of Some Grape and Wine Polysaccharide and Polyphenolic Fractions
JF American Journal of Enology and Viticulture
JO Am. J. Enol. Vitic.
FD American Society for Enology and Viticulture
SP 25
OP 30
VO 47
IS 1
A1 Vernhet, A.
A1 Pellerin, P.
A1 Prieur, C.
A1 Osmianski, J.
A1 Moutounet, M.
YR 1996
UL http://www.ajevonline.org/content/47/1/25.abstract
AB Charge densities of the major wine polysaccharides and of grape seed and wine polyphenols have been determined with a method developed by Mütek (Germany), relying on titration with a counter-charged polyelectrolyte associated to streaming potential measurements. Charge densities were determined in a model hydroalcoholic solution at pH 3.5 and in 10 mM KNO3 solutions, from pH 2 to 9. The polysaccharides tested — yeast mannoproteins, grape arabinogalactan-proteins (AGPs), and rhamnogalacturonan RG-II — carried negative charges in the wine pH range. The net charge density of yeast mannoproteins was shown to be related to their phosphorus content and to be pH-independent in the range tested (2 to 9). Absolute charge densities of AGPs and RG-II were related to the dissociation of the carboxylic functions of their uronic acids and increased dramatically in the pH range 2 to 5. Polyphenolic fractions, including native tannins isolated from grape seeds and polyphenolic fractions recovered from wine, carried no charges or negligible charges at pH 3.5. As a consequence, wine polysaccharides may establish electrostatic and ionic interactions, but such interactions will play little, if any, in the association of polyphenols with other components.