 IVES 9 IVES Conference Series 9 Tuning the pH during the fermentation has a strong effect on the wine protein composition and the stability of the resulting white wines

Tuning the pH during the fermentation has a strong effect on the wine protein composition and the stability of the resulting white wines

Abstract

AIM: Previous results have shown the impact of the pH on the stability of white wine proteins. In a context of global warming that implies increases in ethanol content and pH, we wanted to compare for the same initial must (given composition in polysaccharides, polyphenols, ions, _) the impact of the pH on the protein composition after fermentation. Several white wine varieties were considered.

METHODS: Vinifications were carried out using musts from Sauvignon, Muscat, Sylvaner, Riesling, Gewurztrminer, and Pinot Gris). The pH of the initial musts was adjusted to 3.0, 3.3, 3.6 and 3.9. For each wine thus obtained, heat tests (heating at 40°C for 4 hours) were carried out and proteins were analyzed and quantified by gel electrophoresis.

RESULTS: On the whole, protein concentrations in wines decreased during fermentation. However, this decrease was more marked for the lowest pH (3.0 and 3.3), as well as for some proteins (chitinases, b-glucanases). Thus the total concentration of proteins was higher at pH 3.9. The turbidity measured after heat tests evolved differently: a maximum was observed at pH 3.6 in the present experimental conditions (40°C- 4h).

CONCLUSIONS

This study confirms that the pH has a decisive impact on the protein composition in white wines, with higher pH favoring their conformational stability during winemaking. However, haze formation due to heat-induced denaturation of proteins is higher at high pH. This trend was observed whatever the studied variety, but with more or less haze intensities. This indicated also an impact of non-protein compounds, whose composition strongly depends on the grape variety.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Céline Poncet-Legrand

INRAE,Eric MEISTERMANN, IFV Aude VERNHET, Institut Agro, Montpellier SupAgro Philippe COTTEREAU, IFV Frédéric CHARRIER, IFV Patrick CHEMARDIN, INRAE Céline PONCET-LEGRAND, INRAE

Contact the author

Keywords

white wines, haze formation, proteins, pH

Citation

“Garrigues”, part of the mediterranean vine terroirs

Les paysages viticoles méditerranéens présentent une originalité qui ne se retrouve nulle part ailleurs : ils associent des garrigues très odoriférantes à des parcelles de vignes souvent qualitatives. La connaissance empirique des vins du Languedoc par leurs dégustateurs a conduit la Chambre d’Agriculture de l’Hérault à supposer que les arômes de la garrigue environnante peuvent se retrouver dans les vins (arômes de ciste, de genévrier, … )

Mining belowground and aboveground microbiome data to identify microbial biomarkers of grapevine health and yield

Vineyards are home to a wide diversity of microorganisms that interact with plants and with each other.

Approaches to the classification of wine aroma aging potential. Applications to the case of Valpolicella red wines

Unlike most of other foods, wine sensory quality is thought to reach a peak after an aging period. In the case of the Valpolicella red wines

Bio-modulating wine acidity: The role of non-Saccharomyces yeasts

In this video recording of the IVES science meeting 2021, Alice Maria Correia Vilela (University of Trás-os-Montes and Alto Douro, Vila Real, Portugal) speaks about bio-modulating wine acidity: the role of non-Saccharomyces yeasts. This presentation is based on an original article accessible for free on IVES Technical Reviews.

Varietal thiol precursors in Trebbiano di Lugana grape and must

Trebbiano di Lugana (TdL) is a white variety of Vitis vinifera mainly cultivated in an Italian area located south near Garda lake (Verona, north of Italy). This grape cultivar, also known as “Turbiana,” is used for the production of TdL wine with recognized Protected Designation of Origin whose volatile profile was recently determined [1]. The presence of varietal thiols in TdL, namely 3-mercaptohexan-1-ol and its acetate form, conferring the tropical and citrus notes, has been documented. Winemaking strategies were also described with the purpose of protecting and maintain these desired aromas [2]. To the best of our knowledge, the varietal thiol precursors (VTPs) were not previously determined in TdL grape and must. This study aimed to quantify VTPs in both grape during the ripening and must during the pressing. Volatile C6 compounds were also measured in the must fractions.