Red wine oxidation study by accelerating ageing tests and electrochemical method

Abstract

Red wines can undergo many undesirable changes during the winemaking process and storage, particularly oxidative degradation due to numerous atmospheric oxygen intakes. This spoilage can impact organoleptic properties and color stabilization but this impact depends on the wine composition. Phenolic compounds constitute primary targets to oxidation reactions.
In order to obtain information on the oxidative behavior of red wines, oxygen consumption rates and electrochemical modifications (obtained by cyclic voltammetry) were measured for nine red wines subject to three different accelerated ageing tests (after wine air saturation). Chemical test (hydrogen peroxide add), enzymatic test (laccase from Trametes versicolor add) and temperature test (heat at 60°C) were carried out. Global phenolic composition, metals (Fe and Cu) and free SO2 concentrations were also determined. 
The obtained results showed oxidative behavior depended both on the wine sample and accelerated ageing test type. Good correlations were obtained between electrochemical parameters (charges at different potentials related to reductive properties) for non-oxidized wines and their variation after enzymatic and temperature tests, meaning that cyclic voltammetry could be used in order to predict these two oxidation tests and reflect the wine sensitivity towards respective oxidation targets. To strengthen this, good correlations were also obtained between the electrochemical parameters of the initial wines and oxygen consumption rates for these two tests. However, it was not possible to predict wine chemical oxidation test based on hydrogen peroxide from the electrochemical measurements.