Definition: Glutathione

The role of glutathione in the production of dry white wines, according to Denis Dubourdieu and Valérie Lavigne of the Faculty of Oenology in Bordeaux: glutathione peroxidase, a reducing agent found in our tissues and in fruit. It is an enzyme made up of three amino acids with antioxidant and detoxifying properties, which act as a free radical trap. It is found in large quantities in grapes.

During the various stages of winemaking, the tannins contained in the grape skin tend to oxidise on contact with the air. This is when glutathione comes into play, protecting them by sacrificing itself in part. Then, during the fermentation process, the yeasts use what remains of the glutathione as one of their nutrients. Thus, by the end of alcoholic fermentation, the glutathione has almost disappeared. When the yeasts have finished their work, they die and, in dying, release the glutathione they have fed on.