Estudios de complejación de los metales que influyen en la coloración de los vinos tintos navarros

Résumé

Estudios de complejación de los metales que influyen en la coloración de los vinos titos navarros. Complexation studies of metals affecting Navarra red wine colour. The aim of this thesis is to get a comprehensive picture of the composition and fate of both organic and inorganic fractions of a wine along its vinification period through the quantification of main components and statistical analysis. Measurements of phenolic compounds, colour, target metals and antioxidant activity were done for the Tempranillo variety of Vitis vinifera wines fromNavarra, both under vinification and botthled. The following conlusions were reached: Mathematical expressions were found that allow prediction of certain parameters as a function of the values of other more easily measurable ones. A direct relationship has been found between CIELAB colour para meters and the phenolic compounds present in wine, what makes this system appropriate for quality characterisation of a wine in a cellar. An increase in fe concentration gives rise to batochromic and hyperchoromic effets. This phenomenon is more clearly detectable through CIELAB system rather than the classical one. Chromatic properties of wine remain unaltered with variable Zn ab Cu and Zn and Cyanidin -3- glucoside and petunidin -3- glucoside were disclosed. Voltammetric setudises have allowed to elucidate the type of complex formed by both Zn and Cu with phenolic compounds as catechin, quercetin and rutin at the natural ph of wine. Besides, complexing role of ligands occurring in wine as well as their evolution throughout winemaking is made possible by this technique. Differential pulse anodic stripping voltammetry (DPASV) has proved useful for predicting the proclivity of a wine to undergo cupric casse.