This project aims to extend current understanding about the effects of glutathione additions in white juices and wines, in other varieties as well as in Sauvignon Blanc.
Sulfur dioxide is the antioxidant most commonly used to preserve wine quality, however some consumers have sensitivity to sulfur dioxide and sulphites, and hence more benign antioxidants are sought. Glutathione is a naturally occurring antioxidant from grape and yeast, that appears to provide a solution, and may allow lower concentrations of sulfur dioxide to be used in wine production.
Much of the previous work associated with glutathione manipulation has targeted Sauvignon Blanc, aiming to preserve varietal thiols and colour in bottled wine. While thiols contribute to the character of wines made from other varieties, the impact of glutathione addition on wine quality and style is relatively unknown.
The project will study protective juice treatments, the effects of direct glutathione addition and an assessment of microbial consumption of glutathione. The fate of added glutathione will be determined through use of labelled compounds, which will aid in the determination of the degree to which glutathione turnover contributes to hydrogen sulfide production. Finally, small-scale winemaking trials will be used to assess the sensory and chemical impact of glutathione treatments. This work will elucidate how glutathione, in combination with other factors, can be used during grape processing to preserve grape aroma compounds, wine quality and regional characters.
The new knowledge generated will inform winemakers’ decisions on the applicability and usefulness of glutathione as an additional antioxidant.