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.

An Integrative View of the Role of Lachancea thermotolerans in Wine Technology

“…L. thermotolerans management could be an interesting strategy to reduce the final concentration of sulfur dioxide in wine. Additionally, this effect could synergize with the previously mentioned increases in glutathione [23]. The highest reported reduction compared to an S. cerevisiae control is 95% [14].…”

“…It also allows a reduction in the addition of sulfur dioxide, which is a hazardous compound, especially for specific groups at risk, such as people who suffer from asthma, and its legal limits have decreased in recent years [50]. Some non-Saccharomyces strains have been recently reported to be powerful producers of glutathione [23]. Three strains of L. thermotolerans contain glutathione in concentrations varying from 0.205 to 0.537 nmol/mg cell, while the S. cerevisiae control shows 0.095 nmol/mg cell.…”

“…However, in white wine production, L. thermotolerans strains may be selected to increase the malic acid content by approximately 7% [6], as most white wines do not require malic acid stabilization and could be of additional interest in highly productive, low acidic white grape varieties such as Airen. The production of glutathione up to the maximum concentration reported in wine for a strain of L. thermotolerans of 24 mg/L [23] can be established as the selection level. This may protect wine against oxidation and reduce the addition of sulfur dioxide.…”

“…Recent studies have explored the influence of L. thermotolerans on parameters different from lactic acid acidification but that are still of great interest in modern enology, such as aeration influence [22], glutathione production [23], ethanol reduction [19], sulfur dioxide reduction, [14], polysaccharides production [18], and nitrogen demand.…”

Emerging biotechnologies and non-thermal technologies for winemaking in a context of global warming

“…A non-negligible production of glutathione (GSH) was also observed for Metschnikowia spp. during the growth phase (Lemos Junior et al, 2021); during sequential fermentation, some strains may increase the final GSH content in wine up to 10 mg/L (Binati et al, 2021), potentially reducing oxidation risks and reducing SO 2 requirements.…”