IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Composition and molar mass distribution of different must and wine colloids

Composition and molar mass distribution of different must and wine colloids

Abstract

A major problem for winemakers is the formation of proteinaceous haze after bottling. Although the exact mechanisms remain unclear, this haze is formed by unfolding and agglomeration of grape proteins, being additionally influenced by numerous further factors. For instance, increased levels of polyphenols and sulfate ions, high pH and ionic strength, and increased storage temperatures have been discussed to promote haze formation. In contrast, organic acids and polysaccharides appear to inhibit protein agglomeration (Albuquerque et al. 2021). To avoid haze formation, winemakers use bentonite to reduce protein levels in the wine before bottling. However, the bentonite treatment imposes negative side effects such as losses in wine quantity and quality, as well as costs of bentonite waste disposal (van Sluyter et al. 2015). To better understand haze formation and to find alternative procedures for protein removal e.g. by enzymatic treatments, detailed insights into the composition of the wine colloids might be helpful.
Prior to characterization, colloids were isolated from five different musts (four varieties from five vineyards, three with pectinase treatment) and their corresponding wines by ultrafiltration (10 kDa cut-off) and freeze-drying. Protein and carbohydrate composition were determined after hydrolysis by ion chromatography and high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), respectively. Molar mass distribution of colloids was determined by size exclusion chromatography with multi angle light scattering in combination with an UV and RI detector (SEC-UV-MALS-RI).
Colloids were found to contain a wide range of 8.9 to 67.1 g protein and 28.1 to 78.0 g carbohydrates per 100 g dry matter. Thus, protein concentrations in must and wine were been between 0.06 and 0.40 g/L and carbohydrate concentrations between 0.17 and 0.65 g/L. While there were just minor differences in the amino acid composition between the musts and wines, the carbohydrate composition was different in the samples. For instance, arabinose and galactose were the main sugars found in all hydrolyzed must colloids, while galacturonic acid was present in higher amounts in those not treated with pectinase. After fermentation, mannose was found to be the main sugar in hydrolyzed wine colloids. SEC-UV-MALS-RI showed that the colloids contained three main fractions. Two carbohydrate-rich fractions with average molar masses from 931 to 22,617 kDa and from 80 to 495 kDa as well as a proteinaceous fraction with an average molar mass between 16 to 44 kDa.
Our results indicate that colloid concentration and composition in wine is heavily influenced by variety, vineyard and oenological practices. The isolated colloids and the analytical methods will in the future be used to screen for enzyme preparations suitable to degrade proteins in must and wine to avoid haze formation.

References

Albuquerque, Wendell; Seidel, Leif; Zorn, Holger; Will, Frank; Gand, Martin (2021): Haze Formation and the Challenges for Peptidases in Wine Protein Fining. In: Journal of Agricultural and Food Chemistry 69, S. 14402–14414.
van Sluyter, Steven C.; McRae, Jacqui M.; Falconer, Robert J.; Smith, Paul A.; Bacic, Antony; Waters, Elizabeth J.; Marangon, Matteo (2015): Wine Protein Haze: Mechanisms of Formation and Advances in Prevention. In: Journal of Agricultural and Food Chemistry 63 (16), S. 4020–4030.

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Poster

Authors

Seidel Leif1, Albuquerque Wendell2, Happel Katharina3, Gand Martin2, Zorn Holger2,3, Schweiggert Ralf1 and Will Frank1

1Department of Beverage Research, Geisenheim University
2Institute of Food Chemistry and Food Biotechnology, Justus Liebig Giessen 
3Fraunhofer Institute for Molecular Biology and Applied Ecology, Giessen, Germany

Contact the author

Keywords

wine colloids, proteins, carbohydrates, molar mass

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

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)

How distinctive are single vineyard Gewürztraminer musts and wines from Alto Adige (Italy) based on untargeted analysis, sensory profiling, and chemometric elaboration?

Vitis vinifera L. ‘Gewürztraminer’ is a historical grape variety of Alto Adige (Südtirol), Italy, which is widely grown in the area of Tramin an der Weinstraße, but is also grown globally. It produces highly aromatic wines that are strongly influenced by the terroir of the vineyard sites where they are grown. This study looked at musts and young wines from ‘Gewürztraminer’ grapes harvested in seven distinct vineyards near Tramin and then processed at Cantina di Termeno, minimizing winemaking protocol variability. Samples were profiled using bidimensional gas chromatography–time-of-flight mass spectrometry, liquid chromatography coupled to electrochemical detection, and near-IR spectrometry. The data were subjected to Principle Component Analysis and Hierarchical Clustering Analysis. Sensory discriminant testing was undertaken using the sorting method with a semi-trained panel, and the data were processed using Multidimensional Scaling. Seven must/wine pairs could be distinguished based on their untargeted volatilome profiles and on sensory evaluation. As expected, there were greater differences in the volatile compounds between the wines than between the musts. The wines from vineyards 4 and 5 were nonetheless quite homogenous in terms of chemical and sensory analyses, as were the wines from vineyards 1 and 3. For the phenolic profile, differences were noted between the musts and wines of vineyards 2, 3, and 4, but the musts from vineyards 5 and 7 were similar. Sensory analysis showed the wines from vineyards 6 and 7 to be distinct from the rest. These results reinforce that the composition of ‘Gewürztraminer’ musts and wines is strongly determined by vineyard site, even in a small geographic area with high variability of the terroir (soil and microclimate), and that these differences are apparent in the flavours and aromas of the finished wines. Further confirmation would require a larger sample of wines, preferably from several vintages.

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.

Use of a new, miniaturized, low-cost spectral sensor to estimate and map the vineyard water status from a mobile 

Optimizing the use of water and improving irrigation strategies has become increasingly important in most winegrowing countries due to the consequences of climate change, which are leading to more frequent droughts, heat waves, or alteration of precipitation patterns. Optimized irrigation scheduling can only be based on a reliable knowledge of the vineyard water status.

In this context, this work aims at the development of a novel methodology, using a contactless, miniaturized, low-cost NIR spectral tool to monitor (on-the-go) the vineyard water status variability. On-the-go spectral measurements were acquired in the vineyard using a NIR micro spectrometer, operating in the 900–1900 nm spectral range, from a ground vehicle moving at 3 km/h. Spectral measurements were collected on the northeast side of the canopy across four different dates (July 8th, 14th, 21st and August 12th) during 2021 season in a commercial vineyard (3 ha). Grapevines of Vitis vinifera L. Graciano planted on a VSP trellis were monitored at solar noon using stem water potential (Ψs) as reference indicators of plant water status. In total, 108 measurements of Ψs were taken (27 vines per date).

Calibration and prediction models were performed using Partial Least Squares (PLS) regression. The best prediction models for grapevine water status yielded a determination coefficient of cross-validation (r2cv) of 0.67 and a root mean square error of cross-validation (RMSEcv) of 0.131 MPa. This predictive model was employed to map the spatial variability of the vineyard water status and provided useful, practical information towards the implementation of appropriate irrigation strategies. The outcomes presented in this work show the great potential of this low-cost methodology to assess the vineyard stem water potential and its spatial variability in a commercial vineyard.

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.