COMPOSITION OF TARTRATE PRECIPITATES IN WHITE WINES USED FOR MAKING SPANISH SPARKLING WINE

The composition of tartrate crystals, deposited in various containers that had held white wines used in sparkling wine production, was studied. An improved understanding of the composition of the substances that inhibit KHT precipitation would help achieve higher yields during stabilization of the tartrates in wines. X-ray diffraction and X-ray fluorescence analyses were performed, together with elementary analysis, to determine the crystal phases existing in and the elementary composition of the precipitates, and ultrafiltration was carried out to determine the nature and size of the organic compounds present in the precipitates. The results indicate that the main salt precipitated was in all cases potassium bitartrate. Small quantities of calcium tartrate were also present in the precipitates collected from the containers used for storage or fermentation of the wines. The different stoichiometric balances detected, according to the differing origins of the samples, suggest that there was interference by negatively charged substances in the case of precipitation in the containers used for the storage and fermentation of the wines and by positively charged substances in the case of precipitation in the containers used for cold stabilization. The proteins, peptides, and polyphenols of varying degrees of polymerization that had been adsorbed onto the faces of the crystals were separated by ultrafiltration.