 IVES 9 IVES Conference Series 9 From vineyard to bottle. Rationalizing grape compositional drivers of the expression of valpolicella aroma ‘terroir’

From vineyard to bottle. Rationalizing grape compositional drivers of the expression of valpolicella aroma ‘terroir’

Abstract

AIM: Valpolicella is a renowned Italian wine-producing region (Paronetto, 1981). Wines produced in its different sub-regions are anecdotally believed to be aromatically different, although there is no systematic study addressing the chemical bases of such diversity. Aroma is the product of a biochemical and technological series of steps (Kotseridis, et al., 1999), as well as one of the most important features in the expression of the geographic identity and sensory uniqueness of a wine. The aim of this study was to investigate the volatile chemical composition of wines obtained from grapes harvested in selected vineyards during three consecutive vintages, assess the existence of recurring patterns that could represent unique aroma chemical signatures and to identify key grape compositional features underling such aroma signature.

METHODS: Corvina and Corvinone grapes were harvested from five different vineyards located in two sub-regions within Valpolicella during three consecutive vintages. Winemaking was performed under standardized conditions. Free volatile compounds and glycosidic precursors were analysed with GC-MS analysis co. Sensory characteristics of the wines have been investigated through sorting tasks performed with semi-trained panel.

RESULTS: Application of multivariate data analysis techniques allowed to identify volatile chemical patterns representing the unique aroma chemical signature of the geographical origin of each wine regardless of vintages. The main drivers associated with these chemical signatures were terpenes (linalool, α-terpineol), norisoprenoids (vitispirane, TDN, TPB), and, unexpectedly some fermentation derived esters. Wines’ terpenes content was related with grapes terpenes pool. In particular variations in wine linalool content were strongly associated with the grape content of different linalool forms. Finally, in the case of esters, a strong correlation between grape content of yeast assimilable nitrogen (YAN) and wine ester content was observed, further broadening the boundaries of vineyard factors able to influence wine aroma. Patterns of odor similarities were observed during sensory evaluation, indicating a recurring association between geographical origin and occurrence of aroma compounds such as linear and cyclic terpenes, esters or norisoprenoids.

CONCLUSIONS:

This study provides evidence for the existence of volatile chemical signatures that are representative of geographical origin. Identification of grapes compositional characteristics related to the main drivers of wines chemical signature provides clues to support producers in identifying and managing appropriate vineyard and/or winemaking practices, in the quest of producing wines expressing their sense of place and ‘terroir’

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Giovanni Luzzini

University of Verona,Davide SLAGHENAUFI, University of Verona Maurizio, UGLIANO, University of Verona Jessica, SAMANIEGO-SOLIS, University of Verona Riccardo TEDESCHI, Azienda Agricola F.lli Tedeschi

Contact the author

Keywords

chemical signature of geographical identity, red wine aroma, valpolicella, terroir, crus

Citation

Methoxypyrazine concentrations in grape-bunch rachis are influenced by rootstock, region, light, and scion.

Methoxypyrazines (MPs) are readily extracted from grape berry and rachis during fermentation and can impart “green” and “herbaceous” sensory attributes to wine. Irrespective of whether MPs, including 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP), are extracted from berry or other vine material, techniques for remediation of wine with overpowering sensory characters attributable to MPs suffer from poor specificity or produce undesirable sensory outcomes, meaning that alternative control approaches are needed.

Building new temperature indexes for a local understanding of grapevine physiology

Aim: Temperature corresponds to one of the main terroir factors influencing grapevine physiology, primarily evidenced by its impact on phenology. Numerous studies have aimed at expressing time with thermal indices such as growing degree days (GDD) and have thus enabled a better modelling of grapevine responses to temperature. However, some works have highlighted the need to adapt

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.

Deficit irrigation and mechanical canopy management affect berry and wine phenolic and aroma composition of Syrah in Central California

Labor shortage is one of the most crucial issues in current viticulture. Mechanized approaches are helpful in reducing production costs and increasing vineyard efficiency but their effect on grapes and wines needs evaluation. This work assess the results of combined mechanical pruning and shoot thinning with deficit irrigation strategies to reduce management costs but not quality of production.

Phenotypic variations of primary metabolites yield during alcoholic fermentation in the Saccharomyces cerevisiae species

Saccharomyces cerevisiae, as the workhorse of alcoholic fermentation, is a major actor of winemaking. In this context, this yeast species uses alcoholic fermentation to convert sugars from the grape must into ethanol and CO2 with an outstanding efficiency: it reaches on average 92% of the maximum theoretical yield of conversion. Moreover, S. cerevisiae is also known for its great genetic diversity and plasticity that is directly related to its living environment, natural or technological and therefore to domestication. This leads to a great phenotypic diversity of metabolites production.