Contribution of non‐ Saccharomyces yeasts to increase glutathione concentration in wine

Abstract

Background and Aims Glutathione (GSH), a strong antioxidant naturally present in grape berries and produced by yeasts during fermentation, can be added by winemakers to control oxidative deterioration of wine. A promising approach is the inoculation of starter or co-starter yeasts that are strong producers of GSH in situ. Since little is known about this activity in non-Saccharomyces yeasts, the aim of this research was to evaluate the contribution of several strains of Lachancea thermotolerans, Metschnikowia spp. and Starmerella bacillaris to increase the GSH concentration in wine. Methods and Results Pinot Grigio grape must was sequentially inoculated with the non-Saccharomyces yeasts and Saccharomyces cerevisiae. Some strains significantly increased GSH in wines, notably Metschnikowia spp., up to a surplus of 10 mg/L compared to the Control singly inoculated with S. cerevisiae. Conclusions These results suggest the feasibility of the proposed strategy to increase GSH concentration in wines as an alternative to addition of pure GSH or inactivated dry yeasts. Significance of the Study As the maximum allowed addition of GSH in wine is 20 mg/L, the strategy of mixed-culture fermentation can be a valuable tool to lower inputs, and ultimately obtain a healthier product by reducing the need for sulfur dioxide.