The zeta-potential of the endogenous particles of a wine of Champagne in relation to the foaming behaviour
Résumé
It was shown that the endogenous particles of the champagnes influence the lifetime, and not the maximum expansion of their evanescent foam (Food Hydrocolloids (1999) 12, 217-226). Actually, champagnes are electrolytic solutions with pH 3 and ionic strength equal to 0.02 mol/l in which bentonites, diatomites, and yeast cells are the more numerous colloids and particles present. In this context, we have investigated the electrophoretic properties of these particles to determine whether they can electrostatically interact with the foam bubbles. Results are that in model alcoholic solutions of proteins at same pH and ionic strength as the champagne, the xi -potential was not vanishing whereas it dropped down to zero in wines. The xi -potential of the particles does not vanish either when they are suspended in nanofiltered wines on molecular weight cut-off membrane (porosity = 200-300 Da) or when the wines are basified upon addition of sodium hydroxide. This particular behaviour was tentatively assigned to the adsorption of some endogenous organic cationic ions on the particle surfaces, which screened out their electrostatic charge. The possible candidates are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.