OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 OENO IVAS 9 OENO IVAS 2019 9 Analysis and composition of grapes, wines, wine spirits 9 The fundamental role of pH in the anthocyanins chemical behavior and in their extractability during winemaking

The fundamental role of pH in the anthocyanins chemical behavior and in their extractability during winemaking

Abstract

The chemical behavior of anthocyanins is considerably affected even by slight pH variations with impor-tant implications for the winemaking as well as for the wine conservation. Considering that this is a cen-tral issue to the enological sector, we decided to better investigate the influence of pH on the anthocyanin chemistry.

Initially, by chromatographic and advanced NMR techniques the chemical behavior of malvi-din- 3-O-glucoside was studied in wine-like solutions with pH values ranging from 3 to 4. First, the already composite aqueous equilibrium of malvidin-3-O-glucoside turned out to be even more complex than so far thought, as a new hydration product of the anthocyanin was detected and characterized in solution.

More importantly on account of its technological implications, the anthocyanin solubility appeared to decrease remarkably as the pH value of the wine-like solutions increased. A dramatic drop in terms of anthocyanin solubility was observed at pH 3.32, where the measured molecule concentration was reduced to almost 25% the expected one. Also, at such pH level the anthocyanin self-association appeared significantly affected.

In more detail,the flavylium ion self-association predominant at lower pH levels was altered and found to co-occur with a preferential co-pigmentation involving flavylium ion species and the trans-chalcone form of malvidin-3-O-glucoside. At higher pH values, this latter association was the only one detected in so-lution. In the light of these results, we set up an experimental protocol with the purpose of analyzing the pH influence on the anthocyanin chemistry and extractability in real wines produced by varying their pH levels during the maceration-fermentation phases.

Preliminary chemical analysis of such wines provided data consistent with those obtained in wine-like solutions. Indeed, the extraction of malvidin-3-O-gluco-side and that of anthocyanins in general was more contained as the pH value increased.

Additionally, other molecules of enological interest, including catechins, cinnamates, syringic acid and terpenoids, turned out to be affected by the wine pH. These analytical data highlight the fundamental role of pH during the wine-making and the importance of regulating its level to obtain wines with the desired polyphenolic structure.

Boulton. American journal of enology and viticulture, 52(2), 67-87 (2001). Forino, M., Gambuti, A., Luciano, P., Moio, L. J. Agric. Food Chem. (2019) doi:10.1021/acs.jafc.8b05895 

DOI:

Publication date: June 11, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Martino Forino, Angelita Gambuti, Luigi Picariello, Luigi Moio

Department of Agricultural Sciences, University of Napoli “Federico II”−Oenology Sciences Section Viale Italia, 83100 Avellino, Italy

Contact the author

Keywords

Anthocyanin , pH, pigmentation, anthocyanin solubility

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

Haplotype-resolved genome assemblies of Chasselas and Ugni Blanc

Haplotype-resolved genome assemblies were produced for Chasselas and Ugni Blanc, two heterozygous real-field genetic pool Vitis vinifera cultivars by combining high-fidelity long-read sequencing (HiFi) and high‐throughput chromosome conformation capture (Hi-C). The telomere-to-telomere full coverage of the chromosomes allowed us to assemble separately the two haplo-genomes of both cultivars and revealed structural variations between the two haplotypes of a given cultivar.

“Vinhos de mesa” et oenophilie : quand les caractéristiques organoleptiques des cépages américains empêchent l’intégration des consommateurs à l’univers de l’appréciation esthétique

Au Brésil, 80 % du vignoble national et 90 % du vignoble de l’État du Rio Grande do Sul (principale région productrice de vins dans le pays) sont plantés avec des cépages issus de vitis labrusca ou de cépages hybrides (DEBASTIANI, 2015). Une partie de cette production est utilisée pour la préparation de jus de raisin et de concentrés de moût ou de pulpe de raisin. Le restant est consacré à

The interplay between grape ripening and weather anomalies – A modeling exercise

Current climate change is increasing inter- and intra-annual variability in atmospheric conditions leading to grapevine phenological shifts as well altered grape ripening and composition at ripeness. This study aims to (i) detect weather anomalies within a long-term time series, (ii) model grape ripening revealing altered traits in time to target specific ripeness thresholds for four Vitis vinifera cultivars, and (iii) establish empirical relationships between ripening and weather anomalies with forecasting purposes. The Day of the Year (DOY) to reach specific grape ripeness targets was determined from time series of sugar concentrations, total acidity and pH collected from a private company in the period 2009-2021 in North-Eastern Italy. Non-linear models for the DOY to reach the specified ripeness thresholds were assessed for model efficiency (EF) and error of prediction (RMSE) in four grapevine cultivars (Merlot, Cabernet Sauvignon, Glera and Garganega). For each vintage and cultivar, advances or delays in DOY to target specified ripeness thresholds were assessed with respect to the average ripening dynamics. Long-term meteorological series monitored at ground weather station by means of hourly air temperature and rainfall data were analyzed. Climate statistics were obtained and for each time period (month, bimester, quarter and year) weather anomalies were identified. A linear regression analysis was performed to assess a possible correlation that may exist between ripening and weather anomalies. For each cultivar, ripeness advances or delays expressed in number of days to target the specific ripening threshold were assessed in relation to registered weather anomalies and the specific reference time period in the vintage. Precipitation of the warmest month and spring quarter are key to understanding the effect of climate change on sugar ripeness. Minimum temperatures of May-June bimester and maximum temperatures of spring quarter best correlate with altered total acidity evolution and pH increment during the ripening process, respectively.

Tackling the 3D root system architecture of grapevines: a new phenotyping pipeline based on photogrammetry

Plant roots fulfil important functions as they are responsible for the acquisition of water and nutrients, for anchorage and stability, for interaction with symbionts and, in some cases, for the storage of carbohydrates. These functions are associated with the Root System Architecture (RSA, i.e. the form and the spatial arrangement of the roots in the soil). The RSA results from several biological processes (elongation, ramification, mortality…) genetically determined but with high structural plasticity.

Effects of the synergy between T. delbrueckii and S. cerevisiae in the winemaking of traditional cultivars from southeastern Italy

The combination of Torulaspora delbrueckii and Saccharomyces cerevisiae in co-inoculation and sequential inoculation in winemaking was investigated as an innovative strategy to increase the aromatic profile of wines like Verdeca and Nero di Troia wines, two traditional varieties from south-eastern Italy (Apulia Region).