Terroir 1996 banner
IVES 9 IVES Conference Series 9 Rapid measurement of phenolic quality as a useful tool for viticultural zoning

Rapid measurement of phenolic quality as a useful tool for viticultural zoning

Abstract

Un des principaux objectifs du zonage viticole est l’individuation des zones plus indiquées à la production de vins de haute qualité en relation aux cépages. Ceperrlant depuis beaucqup d’années, entre les paramètres de qualité du raisin, on n’a pas considéré les substances phénoliques par effet de l!l difficulté d’analyse en temps rapides.
En considérant l’importance des polyphénols sur la qualité du raisin, en particulier le raisin rouge, un nouveau système d’évaluation en temps réel d’un indice de qualité phénolique du raisin rouge a été réalisé.
En utilisant un système d’analyse de la couleur particulier dans le spectrum de réflexion, il est possible d’analyser le raisin pendant la maturation ou de classer le raisin au moment de la livraison à la cave. Il s’agit d’un système d’analyse a posteriori, donc il est possible de réaliser un panorama indicatif de la potentialité phénolique des raisins déjà cultivés en différentes zones viticoles et pour chaque cépage.
Les données du présent travail expérimental sont relatives à des évaluations réalisées en Italie, Espagne et Australie au cours des dernières vendanges dans des domaines intéressées par l’évaluation des polyphénols comme paramètre supplémentaire pour la classification des raisins rouges à la livraison.
Les expériences réalisées ont permis de vérifier qu’il n’y a pas des corrélations significatives entre les polyphénols et les sucres à la récolte, en outre l’indice de qualité phénolique qu’on obtient en temps réel sur un échantillon représentatif est un résultat intéressant pour suivre l’évolution de la maturation en vigne.
La conséquence est que de grands projets de caractérisation des zones viticoles seraient peu significatifs si on néglige le patrimoine phénolique comme indice de qualité.
On peut donc affirmer que le système d’analyse rapide utilisé pourrait devenir un instrument efficace à introduire dans les programmes de zonage pour renouveler les données afin de définir la meilleure combinaison terroir x cépage pour la production de raisin avec un potentiel œnologique élevé.

One of the main aims of viticultural zoning is to identify the areas most suited to the production of high-quality wine in relation to each cultivar. In recent years, however, phenolic content as a parameter for assessing grape quality has often been neglected as it is not easy to measure quickly.
In view of the enormous importance of polyphenols in defining grape quality, in particularly black grapes, a new real-time evaluation system has been devised providing a phenolic quality index for black grapes.
Thanks to a special colorimetric system for assessing the reflectance spectrum, the grapes can be analysed during ripening or classified when delivered to the winery. Since this is a grape quality analysis system, it is possible to obtain an indication of the phenolic potential of the grapes already present in the various vine-growing areas and for each cultivar.
The data provided by this study refer to experiments performed in Italy, Spain and Australia in very recent grape harvests at wineries interested in analysis of polyphenols as an additional parameter for classification of black grapes at delivery, prior to start the winemaking process.
Tests showed that there is no significant correlation between the polyphenols and the sugar level at grape harvest, furthermore, the phenolic quality index obtainable in real time on a representative sample is useful for monitoring ripening in the vineyard. This means that wide­-ranging projects for the characterisation of vine-growing areas would have very little significance if the phenolic content were neglected as an index of grape quality.
In the light of these results, the rapid analysis system used could become a valid tool in zoning programs for updating the existing data in order to identify the area x cultivar combination best suited to the production of grapes with a high enological potential.

 

 

 

DOI:

Publication date: February 15, 2022

Issue: Terroir 2002

Type: Article

Authors

E. CELOTTI, G. CARCERERI DE PRATI, F. BATTISTUTTA and R. ZIRONI

Dipartimento di Scienze degli Alimenti, Università degli Studi di Udine, Via Marangoni 97 -33100 Udine/Italie

Contact the author

Keywords

Zonage, Raisin, Qualité Phénolique, Couleur, Polyphénoles
Zoning, Grape, Phenolic Quality, Colour, Polyphenols

Tags

IVES Conference Series | Terroir 2002

Citation

Related articles…

Updating the Winkler index: An analysis of Cabernet sauvignon in Napa Valley’s varied and changing climate

This study aims to create an updated, agile viticultural climate index (similar to the Winkler Index) by performing in-depth analyses of current and historical data from industry partners in several major winegrowing regions. The Winkler Index was developed in the early twentieth century based on analysis of various grape-growing regions in California. The index uses heat accumulation (i.e. Growing Degree Days) throughout the growing season to determine which grape varieties are best suited to each region. As viticultural regions are increasingly subject to the complexity and uncertainty of a changing climate, a more rigorous, agile model is needed to aid grape growers in determining which cultivars to plant where. For the first phase of this study, 21 industry partners throughout Napa Valley shared historical phenology, harvest, viticultural practice, and weather data related to their Cabernet sauvignon vineyard blocks. To complement this data, berry samples were collected throughout the 2021 growing season from 50 vineyard blocks located throughout 16 American Viticultural Areas that were then analyzed for basic berry chemistry and phenolics. These blocks have been mapped using a Geographic Information System (GIS), enabling analysis of altitude, vineyard row orientation, slope, and remotely sensed climate data. Sampling sites were also chosen based on their proximity to a weather station. By analyzing historical data from industry partners and data specifically collected for this study, it is possible to identify key parameters for further analysis. Initial results indicate extreme variability at a high spatial resolution not currently accounted for in modern viticultural climate indices and suggest that viticultural practices play a major role. Using the structure of data collection and analyses developed for the first phase, this project will soon be expanded to other wine regions globally, while continuing data collection in Napa Valley.

Evolution of the amino acids content through grape ripening: Effect of foliar application of methyl jasmonate with or without urea

The parameters that determine the grape quality, and therefore the optimal harvest time, suffer variations during berry ripening, related to climate change, with the widely known problem of the gap between technological and phenolic maturities. However, there are few studies about its incidence on grape nitrogen composition. For this reason, the use of an elicitor, methyl jasmonate (MeJ), alone or with urea, is proposed as a tool to reduce climatic decoupling, allowing to establish the harvest time in order to achieve the optimum grape quality. The aim was to study the effect of MeJ and MeJ+Urea foliar applications on the evolution of Tempranillo amino acids content throughout the grape maturation. Three treatments were foliarly applied, at veraison and 7 days later: control (water), MeJ (10 mM) and MeJ+Urea (10 mM+6 kg N/ha). Grape samples were taken at five stages of maturation: day before the first and second applications, 15 days after the second application (pre-harvest), harvest day, and 15 days after harvest (post-harvest). The amino acids analysis of the samples was carried out by HPLC. Results showed that the evolution of amino acids was similar regardless of the treatment; however, foliar applications influenced the nitrogen compounds content, i.e., there was no qualitative effect but quantitative one. Most of the amino acids reached their maximum concentration in pre-harvest, being higher in grapes from the treatments than in the control. In general, no differences in grape amino acids content were observed between MeJ and MeJ+Urea treatments. Foliar applications with MeJ and MeJ+Urea enhanced the grape amino acids content, without affecting their profile, helping to optimize their quality and allowing to establish a more complete grape ripening standard. Therefore, MeJ and MeJ+Urea foliar applications can be a simple agronomic practice, which has shown promising results in order to enhance the grape quality.

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.

Local adaptation tools to ensure the viticultural sustainability in a changing climate

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Impact of climate change on the viticultural climate of the Protected Designation of Origin “Jumilla” (SE Spain)

Protected Designation of Origin “Jumilla” (PDO Jumilla) is located in the Spanish provinces of Albacete and Murcia, in the South-eastern part of the Iberian Peninsula, where most of the models predict a severe impact of climate change in next decades. PDO Jumilla covers an area of 247,054 hectares, of which more than 22,000 hectares