Biotechnological strategies for controlling wine oxidation

Apart from the controversial positive effects of a moderate wine consumption on human health, wine antioxidant capacity plays a key role in winemaking technology. From juice extraction, until bottle storage, oxygen management is one of the most critical points for making quality wines. In the past, the protection of juice and wine from oxidations was based on the sole use of sulfur dioxide; more recently, the toxicity and the allergenic potential of this additive, together with the increased knowledge on wine oxidation mechanisms, have given rise to new technological approaches and producing trends, leading to a significant reduction of sulfites in winemaking. First of all, it is well known that an equilibrated grape composition and the use of proper transformation technologies reflect a higher stability of wine phenolics. Moreover, wine yeast (Saccharomyces cerevisiae) has a high oxygen consuming capacity, reducing oxidative phenomena during both alcoholic fermentation and wine aging. Yeasts are also used to produce additives (e.g. autolysates), which are available for the winemakers as products rich in antioxidants, e.g. glutathione. In particular, this tripeptide is known as one of the most powerful antioxidant compounds in the living cells; despite its role in preventing must browning has been well established, its activity in wine has still to be clarified. The purpose of this paper is to review the oxidation mechanisms of grape juice and wine, discussing how it is possible to manage them focusing on these approaches, for reducing the use of sulfur dioxide as much as possible