Macrowine 2021
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

Related articles…

Grapevine sugar concentration model in the Douro Superior, Portugal

Increasingly warm and dry climate conditions are challenging the viticulture and winemaking sector. Digital technologies and crop modelling bear the promise to provide practical answers to those challenges. As viticultural activities strongly depend on harvest date, its early prediction is particularly important, since the success of winemaking practices largely depends upon this key event, which should be based on an accurate and advanced plan of the annual cycle. Herein, we demonstrate the creation of modelling tools to assess grape ripeness, through sugar concentration monitoring. The study area, the Portuguese Côa valley wine region, represents an important terroir in the “Douro Superior” subregion. Two varieties (cv. Touriga Nacional and Touriga Franca) grown in five locations across the Côa Region were considered. Sugar accumulation in grapes, with concentrations between 170 and 230 g l-1, was used from 2014 to 2020 as an indicator of technological maturity conditioned by meteorological factors. The climatic time series were retrieved from the EU Copernicus Service, while sugar data were collected by a non-profit organization, ADVID, and by Sogrape, a leading wine company. The software for calibrating and validating this model framework was the Phenology Modeling Platform (PMP), version 5.5, using Sigmoid and growing degree-day (GDD) models for predictions. The performance was assessed through two metrics: Roots Mean Square Error (RMSE) and efficiency coefficient (EFF), while validation was undertaken using leave-one-out cross-validation. Our findings demonstrate that sugar content is mainly dependent on temperature and air humidity. The models achieved a performance of 0.65

VINIoT – Precision viticulture service

The project VINIoT pursues the creation of a new technological vineyard monitoring service, which will allow companies in the wine sector in the SUDOE space to monitor plantations in real time and remotely at various levels of precision. The system is based on spectral images and an IoT architecture that allows assessing parameters of interest viticulture and the collection of data at a precise scale (level of grape, plant, plot or vineyard) will be designed. In France, three subjects were specifically developed: evaluation of maturity, of water stress, and detection of flavescence dorée. For the evaluation of maturity, it has been decided first to work at the berry scale in the laboratory, then at the bunch scale and finally in the vineyard. The acquisition of the spectral hyperstal image as well as the reference analyzes to measure the maturity, were carried out in the laboratory after harvesting the berries in a maturity monitoring context. This work focuses on a case study to predict sugar content of three different grape varieties: Syrah, Fer Servadou and Mauzac. A robust method called Roboost-PLSR, developed in the framework of this work (Courand et al., 2022), to improve prediction model performance was applied on spectra after the acquirement of hyperspectral images. Regarding the evaluation of water stress, to work with a significant variability in terms of water status, it has been worked first with potted plants under 2 different water regimes. The facilities have allowed the supervision of irrigation and micro-climatic conditions. The regression models on agronomic variables (stomatal conductance, water potential, …) are studied. To detect flavescence dorée, the experimental plan has consisted of work at leaf scale in the laboratory first, and then in the field. To detect the disease from hyper-spectral imaging, a combination of multivariate curve resolution-alternating least squares (MCR-ALS) and factorial discriminant analysis (FDA) was proposed. This strategy proved the potential towards the discrimination of healthy and infected leaves by flavescence dorée based on the use of hyperspectral images (Mas Garcia et al., 2021).

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)

Biodiversity in the vineyard agroecosystem: exploring systemic approaches

Biodiversity conservation and restoration are essential for guarantee the provision of ecosystem services associated to vineyard agroecosystem such as climate regulation trough carbon sequestration and control of pests and diseases. Most of published research dealing with the complexity of the vineyard agroecosystems emphasizes the necessity of innovative approaches, including the integration of information at different temporal and spatial scales and development of systemic analysis based on modelling. A biodiversity survey was conducted in the Franciacorta wine-growing area (Lombardy, Italy), one of the most important Italian wine-growing regions for sparkling wine production, considering a portion of the territory of 112 ha. The area was divided into several Environmental Units (EUs), defined as a whole vineyard or portion of vineyard homogenous in terms of four agronomic characteristics: planting year, planting density, cultivar, and training system. In each EU a set of compartments was identified and characterised by specific variables. The compartments are meteorology, morphology (altitude, slope, aspect, row orientation, and solar irradiance), ecological infrastructures and management. The landscape surrounding EU was also characterised in terms of land-use in a buffer zone of 500 m. For each component a specific methodology was identified and applied. Different statistical approaches were used to evaluate the method to integrate the information related to different compartments within the EU and related to the buffer zone. These approaches were also preliminarily evaluated for their ability to describe the contribution of biodiversity and landscape components to ecosystem services. This methodological exploration provides useful indication for the development of a fully systemic approach to structural and functional biodiversity in vineyard agroecosystems, contributing to promote a multifunctional perspective for the all wine-growing sector.

Geospatial trends of bioclimatic indexes in the topographically complex region of Barolo DOCG

Barolo DOCG is an economically important wine producing region in Northwest Italy. It is a small region of approximately 70 km2 gross area. The topography is very complex with steep sloped hills ranging in elevation from below 200 m to 550 m. Barolo DOCG wine is made exclusively from the Nebbiolo grape. Bioclimatic indexes are often used in viticulture to gain a better understanding of broader climate trends which can be compared temporally and geographically. These indexes are also used for identifying potential phenological timing, growing region suitability, and potential risks associated with expected climatic changes. Understanding how topography influences bioclimatic indexes can help with understanding of mesoscale climate behaviour leading to improved decision making and risk management strategies. The average monthly maximum and minimum temperatures, the Cool Night Index, the Huglin Index, and the monthly diurnal range (from July to October) were calculated using data from 45 weather stations within a 40 km radius of the Barolo DOCG growing area between the years 1996 and 2019. Linear and multiple regression models were developed using independent variables (elevation, aspect, slope) extracted from a digital elevation model to identify significant relationships. Bioclimatic indexes were then kriged with external drift using independent variables that showed significant relationships with the bioclimatic index using a 100 m resolution grid. The maximum monthly temperatures and the Huglin Index showed consistent significant negative relationships with elevation in all years. The minimum monthly temperatures showed no relationship with elevation but in some months a small but significant relationship was observed with aspect. Due to the lack of a relationship between minimum monthly temperatures and elevation compared to the significant relationship between maximum monthly temperatures and elevation, monthly diurnal range had a negative relationship with elevation.