 IVES 9 IVES Conference Series 9 Assessment of wine non-Saccharomyces yeast strains as promising producers of glutathione

Assessment of wine non-Saccharomyces yeast strains as promising producers of glutathione

Abstract

AIM: Glutathione (GSH) is a non-protein thiol naturally present in grape berries and produced by yeasts during fermentation. It has a strong antioxidant activity, thus can be added during winemaking to limit the oxidative phenomena of wine, preserving sensory characteristics and stability, ultimately promoting a healthier product by reducing the need for SO₂ addition. A promising alternative approach could be the use of yeast starter cultures high-producers of this compound in situ, during the fermentation process, in substitution of external GSH addition. Since this activity in non-Saccharomyces yeasts is currently poorly investigated, the aim of this research was to evaluate the ability of three strains of non-Saccharomyces (NS) yeasts to produce GSH, both in synthetic media and in fresh grape must.

METHODS: Lachancea thermotolerans SOL13, Metschnikowia sp. FIANO12, and Starmerella bacillaris MALV45 were tested in single or sequential inoculations,with Saccharomyces cerevisiae EC1118, in synthetic grape juice (SGJ) or in Pinot Grigio grape must, under static conditions, or in a medium optimized for GSH production (MGSH) in agitation (200 rpm). GSH concentration was determined using the Glutathione Assay Kit (Sigma-Aldrich). Population dynamics was evaluated by plate count and biomass dry weight, and fermentation kinetics through weight loss measurement.

RESULTS: A variability in GSH production was found among individual strains and growth conditions. Metschnikowia sp. FIANO12 showed the highest intracellular accumulation of GSH when cultivated alone in both synthetic media, and, as expected, higher levels in the optimized MGSH than in SGJ (4.59 vs. 0.19 nmol GSH/mg cells, respectively). In wine, fermentations with S. bacillaris MALV45 had the highest concentration of intracellular GSH, but the lowest content of wine-dissolved GSH. The maximum level of extracellular GSH (21 mg/L) was obtained in the sequential fermentation with L. thermotolerans SOL13, a significant increase compared to the control singly inoculated with S. cerevisiae.

CONCLUSIONS:

This study highlights a new potential interesting feature of NS yeasts to positively modify wine composition. The tested native strains, with previously demonstrated interesting oenological traits, showed a good capacity to accumulate GSH and to increase the concentration of this antioxidant compound in wine. Thus, the strategy of multi-starter fermentation can be a valuable tool to achieve a lower input winemaking. Future investigations are needed to assess the long-term stability of wine made from multi-starter fermentations with NS yeasts producers of GSH.ACKNOWLEDGEMENTS: We thank Nicolò Bersani for laboratory assistance.

DOI:

Publication date: September 3, 2021

Issue: Macrowine 2021

Type: Article

Authors

Renato L. Binati, Wilson J.F. LEMOS JUNIOR, Sandra TORRIANI

Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy, Department of Biotechnology, University of Verona, Italy

Contact the author

Keywords

Glutathione production, multi-starter fermentation, non-saccharomyces yeasts, saccharomycescerevisiae, winemaking, wine quality

Citation

INFLUENCE OF GRAPE RIPENESS ON MACROMOLECULES EXTRACTABILITY FROM GRAPE SKIN TISSUES AND GRAPE SEEDS DURING WINEMAKING

A consequence of climate change is the modification of grape harvest quality and physico-chemical parameters of the obtained wine: increase in alcoholic degree, decrease in pH, and modification of the extractability of macromolecules, which leads to problems of microbiological, tartaric, colour and colloidal stability. In order to respond to these problems, the winemaking processes must be anticipated and adapted with a better knowledge of macromolecule extractability in grapes and their evolution, according to the grape variety, vintage and winemaking process. The purpose of this study was to understand 1) how the harvest date can influence the extractability of macromolecules, polysaccharides and phenolic compounds, which are responsible for wine stability 2) how to adapt the winemaking process to the harvest date in order to optimise wine quality.

Is it possible to approximate the technological and phenolic maturity of grapes by foliar application of elicitors?

The increase in the temperature and the more severe water stress conditions, trends observed in recent years as a consequence of climate change, are leading a mismatch between the technological and phenolic maturity of grapes

Olfactometric and sensory study of red wines subjected to ultrasound or microwaves during their elaboration

The effect that some extraction techniques, such as ultrasound (Cacciola, Batllò, Ferraretto, Vincenzi, & Celotti, 2013; Povey & McClements, 1988) or microwaves (Carew, Close, & Dambergs, 2015; Carew, Gill, Close, & Dambergs, 2014) produce on the aroma of red wines, when applied to processes of extractive nature, such as pre-fermentative maceration or ageing with oak chips (Spanish oak – Quercus pyrenaica and French oak – Quercus robur) has been studied. The volatile profile was determined by means of gas chromatography coupled with olfactometric and mass spectrometric detection. A sensory analysis was also carried out. No indications were found to show that the pre-fermentative treatment with microwaves or ultrasound modified the sensory profile of the wines whereas the application of such energies during the ageing phase showed some positive trends at sensory level.

Application of ultrasonic and refractometric measurements in enological samples and related model solutions

AIM: The refractive index is a basic optical property of materials and a key tool for the determination of major components in musts, such as sugars

Legacy of land-cover changes on soil erosion and microbiology in Burgundian vineyards

Soils in vineyards are recognized as complex agrosystems whose characteristics reflect complex interactions between natural factors (lithology, climate, slope, biodiversity) and human activities. To date, most of the unknown lies in an incomplete understanding of soil ecosystems, and specifically in the microbial biodiversity even though soil microbiota is involved in many key functions, such as nutrient cycling and carbon sequestration. Soil biological properties are indicative of soil quality. Therefore, understanding how soil communities are related to soil ecosystem functioning is becoming an essential issue for soil strategy conservation. Here, we propose to assess the importance of land-cover history on the present-day microbiological and physico-chemical properties. The studied area was selected in the Burgundian vineyards (Pernand-Vergelesses, Burgundy, France) where land occupation has been reconstructed over the last 40 years. Soil samples were collected in five areas reflecting various land cover history (forest, vineyards, shifting from forest to vineyards). For each area, physico-chemical parameters (pH, C, N, P, grain size) were measured and DNA was extracted to characterize the abundance and diversity of microbial communities. The obtained results show significant differences in the five areas suggesting that present-day microbial molecular biomass and bacterial taxonomic is partly inherited from past land occupation. Over longer period of time, such study of land-uses legacies may help to better assess ecosystem recovery and the impact of management practices for a better soil quality and vineyards sustainability.