Quinone Reactions in Wine Oxidation

Wine oxidation chemistry involves two major steps as first described by Singleton. The formation of quinones from phenolics followed by the creation of acetaldehyde from ethanol. Quinones react with several wine nucleophiles including thiols and the tannin phloroglucinol group. The quinones can also react with SO2 and ascorbic acid as antioxidants. Reactions with aromatic varietal thiols results in the loss of fruity aromas, and phenolics can produce brown products, both oxidative degradation of the wine. However, SO2, ascorbic acid and glutathione all react very quickly with quinones and thus can be protective antioxidants by intercepting the quinone, avoiding oxidative degradation reactions. Competitive reaction kinetics may provide predictive tools for managing wine oxidation.