C. Pascal¹, N. Champeau¹, E. Charpentier¹, E. Brenon¹, JB. Diéval¹, S. Vidal¹, M. Moutounet^2
1 Vinventions, France Oenology Team
² Independent Consultant, Montpellier, France

The longevity of wines depends on their oxidative evolution, more or less rapid under given conditions, and on the acceptability of the presence of signs of oxidation for a given organoleptic profile. Determining a wine’s sensitivity to oxidation, i.e. the risk of oxidative notes appearing when in contact with oxygen, is of practical interest for better control of vinification, maturation and bottle ageing, by making informed choices for carrying out operations on the wines.

The aim of this work is to develop a method for assessing the sensitivity to oxidation of wines. To achieve this, the air resistance method was implemented with electrochemical monitoring on a set of wines whose sensitivity to oxidation had been previously categorized by expert winemakers.  The evolution of the wine’s electrochemical signal between contact with air and after 2 hours of contact enabled the categorization of samples that were sensitive or, on the contrary, resistant to oxidation.

To understand the origin of these signal changes, electrochemical measurements were carried out on solutions of catechin, chosen here as a model phenolic compound, in the presence of Fe(II) or Fe(III) ions under anoxic conditions. The greater or lesser ability of semiquinones, the oxidation products of phenolic compounds, to form complexes with Fe(II) ions could prevent the latter from reacting according to the Fenton reaction and thus prevent the formation of oxidation markers in wines.

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