Electrochemical Microoxidation Of Red Wine

摘要

A new approach to red wine aging was examined that uses a current passed continuously through glassy carbon electrodes in a process of electrochemical microoxidation. A Cabernet Sauvignon wine in 300-L tanks was subject to treatments run in triplicate over 12 weeks at 16℃ consisting of a control, oxygenation to 0.67 mg/L twice weekly (equivalent to 4 mL O_2 per liter wine per month), and electrochemical oxidation of 6144 uA using 250 × 6-mm glassy carbon rods. The potential at the electrode was observed to exceed 2V, where both oxidation of wine polyphenols and direct oxidation of ethanol can occur. While there was considerable loss of bound SO_2, in the oxygenated wines, the concentration of bound SO_2 in the electrochemical microoxidation wines actually increased as the trial proceeded, consistent with the rise in acetaldehyde observed in these wines during the final weeks of the trial. There was little change in concentrations of individual polyphenols, although the rate of decline in monomeric anthocyanins and free quercetin was greater in the oxygenated and electrochemical microoxidated wines than in the controls. Spectrophotometric measures showed an increase in SO_2-resistant pigments and a larger modified hue value (420/520 nm) in both oxygenated and electrochemical microoxidated wines. Electrochemical microoxidation provides an alternative technology for aging red wines with precise control of the rate of oxidation and treatment cut-off.