 IVES 9 IVES Conference Series 9 Exploring the resistance of non-Saccharomyces wine yeasts to dehydration-rehydration processes

Exploring the resistance of non-Saccharomyces wine yeasts to dehydration-rehydration processes

Abstract

AIM: The use of non-Saccharomyces (NS) yeasts in multi-starter fermentations with S. cerevisiae is a trend in the wine industry, but the number of strains commercially available in a powder formulation, such as active dry yeasts (ADY), is still limited. Considering that NS strains are bioresources which could boost innovation in the wine sector, efficient production of powder formulations is of utmost importance to valorise bioresources outside the laboratory environment.

METHODS: Three strains with high oenological potential, selected in previous studies, namely Lachancea thermotolerans DBT027, Metschnikowia sp. DBT012 and Starmerella bacillaris DBT045 were grown in a sterilized medium mainly constituted by grape juice with yeast assimilable nitrogen integration. Early stationary growth phase cultures were collected and suspended in 1% yeast extract, for powder production. The three prototype batches were rehydrated in tap water, to mimic winery conditions, for 15 minutes at four temperatures (20, 25, 30 and 35 ºC). Survival rates of yeasts were assessed before and after rehydration, and after storage at -20 ºC. The same powder NS yeasts were also in multi-starter fermentations in winery and their persistence was monitored.

RESULTS: The selected NS yeast strains were able to grow in the production medium with similar yields, and the powder formulation retained elevated cell viability (around 109-1010 cells/g). The optimal rehydration temperature was different for the three strains: Metschnikowia sp. DBT012 and L. thermotolerans DBT027 maintained higher survival at 35 ºC, while S. bacillaris DBT045 at 20 ºC, as could be expected considering the phenotypic characteristics of the species. Technological performances of the tested powder formulations were satisfactory, especially for DBT012, which was able to grow in grape must after inoculation and dominated over the indigenous microbiota.

CONCLUSIONS

The applied protocol for producing NS yeasts in the powder formulation was successful, as they retained high viability during rehydration and suitable activity when inoculated in must. Powder formulation guaranteed the conservation of the same batch for several comparative tests, bringing out their positive contribution to innovative winemaking biotechnologies. The ability to withstand a larger scale process of biomass production is essential for the exploitation of suitable non-Saccharomyces yeasts selected among a collection of yeast strains with proven oenological potential at laboratory scale. ACKNOWLEDGMENTS: Research developed in the framework of POR FESR 2014-2020 Regione del Veneto, project VIT-VIVE

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Giovanna Felis

Department of Biotechnology, University of Verona, Italy,Renato Leal BINATI, Dept. Biotechnology, University of Verona, Italy Eleonora TROIANO, Dept. Biotechnology, University of Verona, Italy Sandra TORRIANI, Dept. Biotechnology, University of Verona, Italy Marta TEBALDI, Microbion S.r.L. Italy Alessandro RONCADOR, Microbion S.r.L. Italy Fabio FRACCHETTI, Microbion S.r.L. Italy

Contact the author

Keywords

starter cultures, biomass production, dehydration, active dry yeasts

Citation

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.