Macrowine 2021
IVES 9 IVES Conference Series 9 Does bioprotection by adding yeasts present antioxydant properties?

Does bioprotection by adding yeasts present antioxydant properties?

Abstract

AIM: The bioprotection by adding yeasts is an emerging sulfur dioxide alternative. Sulfur dioxide is a chemical adjuvant used for its antiseptic, antioxidasic and antioxidant properties. Faced with the societal demand (Pérès et al., 2018) and considering the proven human risks associated with the total doses of sulfur dioxide (SO2) present in food requirements (García‐Gavín et al., 2012), the reduction of this chemical input is undeniable. Bioprotection allows the control of microbial communities by occupying the grape must niche (Simonin et al., 2018; Windholtz et al., 2021), but no studies have been conducted on its antioxidant properties. Indeed, in must, reaction cascades can take place, bringing into play different compounds that can lead to its undesired browning under the action of polyphenols oxydases. SO2 neutralizes these enzymes and regenerates the quinones. In the present study, bioprotection have been considered for its action on oxidation and on the availability of dissolved oxygen (O2).

METHODS: In order to evaluate the potential impact of bioprotection on dissolved O2 content, an experiment was conducted using semillon must. Three treatments were applicated: SO2 at 50 mg/L, without SO2 and bioprotection composed of two yeast species (Torulaspora delbrueckii and Metschnikowia pulcherrima in the same proportion) at 50 mg/L. O2 concentration was monitored during pre-fermentation phase, using a FireStingO2 compact oximeter (pyroscience, Aix-La-Chappelle, Allemagne). The glutathione, a natural antioxydant compound, was quantified in the musts and wines.

RESULTS: Based on dissolved O2 kinetics, the use of bioprotection led to a rapid consumption of O2 and limited browning comparing to the control, without SO2. The addition of SO2,by neutralizing the polyphenol oxydases (Ough and Crowell, 1987), also limited the O2 consumption. Bioprotection treatment allowed obtaining a significant higher concentration of glutathione in the finished wines than the control without SO2, thus allowing an interesting additional protection during bottle aging.

CONCLUSIONS:

For the first time, this work highlighted the limitation of the white must oxidation by using non-Saccharomyces yeasts as bioprotection in a context of without SO2. By decreasing the availability of dissolved oxygen, bioprotection by adding yeast would slowing down the oxidation cascades. Furthermore, preservation of glutathione by bioprotection allows additional protection in wines.

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Sara Windholtz, Claudia, Isabelle, Cécile

Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, ISVV, F33882 Villenave d’Ornon France , NIOI, Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, ISVV, F33882 Villenave d’Ornon France  Pascaline, REDON, Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, ISVV, F33882 Villenave d’Ornon France, MASNEUF-POMAREDE, Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, ISVV, F33882 Villenave d’Ornon France ; Bordeaux Sciences Agro, Gradignan, France, THIBON, Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Univ. Bordeaux, Bordeaux INP, ISVV, F33882 Villenave d’Ornon France

Contact the author

Keywords

bioprotection, oxygen consumption, gluthathion, white wine

Citation

Related articles…

austrianvineyards.com: online viewer of all designations of Austrian wine

To digitally record and present all the origins of Austrian wines in the same perfect and clear way was the motivation for the Austrian Wine Marketing Board (Austrian Wine) to start with the project in 2018. In June 2021 the results were presented to the public in an online viewer showing all the designations of Austrian wine, available at https://austrianvineyards.com in a largely barrier-free manner. The online viewer provides tailored individual maps fitted to the respective zoom level. The smallest unit of wine-origins in Austria is called Ried and is displayed in a plot-specific manner highlighting areas under vine. Information on the Ried include administrative district, winegrowing municipality, cadastral municipality, large collective vineyard site, specific winegrowing region, generic winegrowing region, winegrowing area and, in many cases, an illustrative picture. Complementary data on the size, elevation (minimum-maximum), orientation (in 8 sectors plus flat) and gradient (minimum, maximum, average) are based on the area under vine according to the EU’s Integrated Administration and Control System. Additional information covers climate data. The diagrams are taken from the monthly breakdown of data in the annals of the Central Institute for Meteorology and Geodynamics, Austria provide a display of values for air temperature, precipitation, and sunshine hours for the reference year and the long-term average. Seasonal aggregated data on temperature, precipitation, and sunshine hours complete the display. Short descriptions with emphasis on geology and soil, field name in historical maps, etymology of the denomination, and main planted variety complements the available information for the main designations in the online viewer. These descriptions are compiled by winegrowers, geologists, historians, and journalists. All the information and data can be extracted to a pdf-file. Printed vineyard maps are also available. Missing content regarding wine origins in Styria will be completed in winter 2021/22.

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).

VINIoT: Precision viticulture service for SMEs based on IoT sensors network

The main innovation in the VINIoT service is the joint use of two technologies that are currently used separately: vineyard monitoring using multispectral imaging and deployed terrain sensors. One part of the system is based on the development of artificial intelligence algorithms that are feed on the images of the multispectral camera and IoT sensors, high-level information on water stress, grape ripening status and the presence of diseases. In order to obtain algorithms to determine the state of ripening of the grapes and avoid losing information due to the diversity of the grape berries, it was decided to work along the first year 2020 at berry scale in the laboratory, during the second year at the cluster scale and on the last year at plot scale. Different varieties of white and red grapes were used; in the case of Galicia we worked with the white grape variety Treixadura and the red variety Mencía. During the 2020 and 2021 campaigns, multispectral images were taken in the visible and infrared range of: 1) sets of 100 grapes classifying them by means of densimetric baths, 2) individual bunches. The images taken with the laboratory analysis of the ripening stage were correlated. Technological maturity, pH, probable degree, malic acid content, tartaric acid content and parameters for assessing phenolic maturity, IPT, anthocyanin content were determined. It has been calculated for each single image the mean value of each spectral band (only taking into account the pixels of interest) and a correlation study of these values with laboratory data has been carried out. These studies are still provisional and it will be necessary to continue with them, jointly with the training of the machine learning algorithms. Processed data will allow to determine the sensitivity of the multispectral images and select bands of interest in maturation.

The combined effects of climate, soils, and deficit irrigation on yield and quality of Touriga Nacional under high atmospheric demand in the Douro Region

Global warming is one of the biggest environmental, social and economic threats in several viticultural regions. In the Douro Valley, changes are expected in the coming years, namely an increase in temperature and a decrease in precipitation. These changes are likely to have consequences for the production and quality of wine.
The aim of this study was to explore the effects of different soil characteristics combined with several deficit irrigation strategies, managed throughout ETc references and predawn leaf water potentials thresholds, on physiology, yield, and qualitative attributes on the Touriga Nacional variety under years of mild to severe water and heat stress.
The studies were conducted over seven years (2015 to 2021) in two plots of a commercial vineyard located at Quinta do Ataíde (Symington Family Estates) planted in 2011 and 2014 at 170 meters elevation, growing under three water regimes: non-irrigated (NI) and two deficit irrigation strategies (30% and 60% ETc) assessed weekly by Ψpd. The site has an annual rainfall below 500 mm, with high atmospheric demand. Climate data was collected from a weather station, located on site. Berry ripening was followed weekly for fruit analysis. At harvest, yield, vigour and pruning weight per vine were determined from 90 vines by treatment. Each season at veraison the NDVI Index was accessed by a drone. The soils physic-chemistry in the experimental blocs were analysed and grouped by SWHC. Delta C-13 analyses were also performed per treatment in two years.Irrigation had a positive effect on yield per vine, mostly due to an increase in berry and cluster weight, and fertility index through the years. A significant increase in sugar content, colour and phenols was observed with deficit irrigation in some years, but vine vigour related to soil characteristics had by far the greatest impact on quality.

The concept of terroir: what place for microbiota?

Microbes play key roles on crop nutrient availability via biogeochemical cycles, rhizosphere interactions with roots as well as on plant growth and health. Recent advances in technologies, such as High Throughput Sequencing Techniques, allowed to gain deeper insight on the structure of bacterial and fungal communities associated with soil, rhizosphere and plant phyllosphere. Over the past 10 years, numerous scientific studies have been carried out on the microbial component of the vineyard. Whether the soil or grape compartments have been taken into account, many studies agree on the evidence of regional delineations of microbial communities, that may contribute to regional wine characteristics and typicity. Some authors proposed the term “microbial terroir” including “yeast terroir” for grapes to describe the connection between microbial biogeography and regional wine characteristics. Many factors are involved in terroir including climate, soil, cultivar and human practices as well as their interactions. Studies considering “microbial terroir” greatly contributed to improve our knowledge on factors that shape the vineyard microbial structure and diversity. However, the potential impact of “microbial terroir” on wine composition has yet not received strong scientific evidence and many questions remain to be addressed, related to the functional characterization of the microbial community and its impact on plant physiology and grape composition, the origins and interannual stability of vineyard microbiota, as well as their impact on wine sensorial attributes. The presentation will give an overview on the role of microbiota as a terroir component and will highlight future perspectives and challenges on this key subject for the wine industry.