Influence of metal ions on lead complexation in wine

• Autores: Alison M. Green, Geoffrey R. Scollary
• Localización: Australian journal of grape and wine research, ISSN 1322-7130, Vol. 6, Nº 3, 2000, págs. 197-202
• Idioma: inglés
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• Resumen

  • Lead in wine is recognised as a potential health risk, but the total lead concentration of wine is not necessarily an indication of bioavailability. A more realistic approach to potential bioavailability is to study the chemical distribution of lead and examine factors that will influence this distribution. Stripping potentiometry, which enables a dynamic study of lead chemistry, was used to monitor the influence of strontium, barium, calcium, zinc, copper and potassium on lead binding in wine. Strontium was found to displace part of the bound lead, whereas barium caused an initial release of lead which was subsequently reincorporated. Zinc, calcium, copper and potassium had no effect on lead complexation. Competitive experiments involving lead and strontium or lead and barium showed that strontium limits the binding of lead, but that barium has little effect overall except on the initial rate of incorporation of lead. The observations are interpreted in terms of the ability of the acidic polysaccharide rhamnogalacturonan-II to interact with lead, strontium and barium, but not with other cations. Some advantages of stripping potentiometry as a method to study the labile lead concentration, as influenced by strontium and barium, are outlined.