Evaluating the Potential of Gamma-Glutamylcysteine and Glutathione as Substitutes for SO2 in White Wine

Sulfur dioxide (SO₂) is the most common additive used in winemaking with its antimicrobial and antioxidant properties. However, in recent years, there has been an increasing tendency to reduce the use of excessive SO₂ in wine due to its negative effects on human health and organoleptic characteristics. Therefore, the aim of this study was to evaluate the potential use of glutathione (GSH) and its precursor, gamma-glutamyl-cysteine (gGC), which are known as strong antioxidants, for substituting SO₂ in white wines. The Turkish indigenous white grape cultivar, Narince (Vitis vinifera), was used to produce white wine. The wines with additions (SO₂, gGC, and GSH) and those without (control) were matured for 2 months. As a result, the protective effects of gGC and GSH additions on phenolic compounds, as well as their ability to reduce browning in white wine, were demonstrated. The addition of gGC and GSH enhanced the amount of esters and higher alcohols, improving the wine's aroma. In conclusion, gGC and GSH—particularly gGC—showed great potential as SO₂ replacements in wine.