 IVES 9 IVES Conference Series 9 Macrowine 9 Macrowine 2021 9 Chemical diversity of 'special' wine styles: fortified wines, passito style, botrytized and ice wines, orange wines, sparkling wines 9 Influence of withering on valpolicella docgs grapes volatile composition

Influence of withering on valpolicella docgs grapes volatile composition

Abstract

AIM: The blend of grapes used in the production of the four Valpolicella PDOs red wines, namely Valpolicella, Valpolicella Classico Superiore, Recioto della Valpolicella and Amarone della Valpolicella is quite unique, and includes two main varieties Corvina and Corvinone, and other minor varieties. To a very large extent all these grapes are only grown in the province of Verona. One of the main characteristics of Valpolicella is the use of grapes that are submitted to post-harvest withering. The aim of this study was therefore to evaluate the evolution of the free and glycosidically-bound volatile compounds in Corvina and Corvinone grapes under real production conditions.

METHODS: Corvina and Corvinone grapes from five different vineyards, at harvest and after 90 days of withering, were obtained from local winery during three consecutive vintages. Grape extracts were prepared with 800 grams of hand-crushed destemmed berries to which 141 mL of ethanol, 400 µg of dimethyl dicarbonate and 80 mg of potassium metabisulphite were added. Bottles were closed with screw caps and kept at 22 ± 1 °C for 14 days, during which they were hand stirred two times per day without opening the caps. Free volatile compounds and glycosidic precursors have been analysed by means of SPE- and SPME-GC-MS methods.

RESULTS: Most free and bound volatile increased in concentration with withering, in agreement with the fact that this process involve a significant degree of water loss (typically around 30%). However, for some compounds a decrease was observed with withering, including free cis-3-hexen-1-ol, 3-hydroxy-β-damascone and methyl salicylate. In the case of terpenes, more complex withering varieties interactions were observed. While in Corvinone all free terpenes increased with withering, in Corvina different patterns were observed, since β-citronellol and other terpenes increased while geraniol, linalool and α-terpineol showed similar content after treatment. Likewise, bound terpenes decreased in Corvina with withering, while in Corvinone they increased in two vintages out of three.

CONCLUSIONS:

Withering is a complex process in which, in addition to the simple water loss, a number of complex biochemical transformations occur inside the grape berry. These can affect volatile compounds of potential sensory relevance for Valpolicella wines in particular terpenes and norisoprenoids. Some variety-related differences in the evolution of certain aroma compounds during withering have been observed, with important consequences for the practical management of post-harvest withering.

ACKNOWLEDGMENTS:

Azienda Agricola f.lli Tedeschi is acknowledged for financial support

DOI:

Publication date: September 15, 2021

Issue: Macrowine 2021

Type: Article

Authors

Giovanni Luzzini

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

Contact the author

Keywords

withered grapes, grape volatile compounds, valpolicella, amarone, recioto

Citation

Climate change projections to support the transition to climate-smart viticulture

The Earth’s system is undergoing major changes through a wide range of spatial and temporal scales as a response to growing anthropogenic radiative forcing, which is pushing the whole system far beyond its natural variability. Sources of greenhouse gases largely exceed their sinks, thus leading to a strengthened greenhouse effect. More energy is thereby being supplied to the system, with inevitable shifts in climatic patterns and weather regimes. Over the last decades, these modifications have been manifested in the full statistical distributions of the atmospheric variables, with dramatic changes in the frequency and intensity of extremes. Natural hazards, such as severe droughts, floods, forest fires, or heatwaves, are being triggered by extreme atmospheric events worldwide, thus threatening human activities. Viticultculture is not only exposed to changing climates but is also highly vulnerable, as grapevine phenology and physiological development are strongly controlled by atmospheric conditions. Therefore, the assessment of climate change projections for a given region is critical for climate change adaptation and risk reduction in viticulture. By adopting timely and suitable measures, the future sustainability and resiliency of the sector can be fostered. Climate-grapevine chain modelling is an essential tool for better planning and management. However, the accuracy of the resulting projections is limited by many uncertainties that must be duly taken into account when transferring knowledge to stakeholders and decision-makers. Climate-smart viticulture will comprise ensembles of locally tuned strategies, envisioning both adaptation and mitigation, assisted by emerging technologies and decision-support systems.

Wine yeast species show strong inter- and intra-specific variability in their sensitivity to uv-c radiation

While the trend in winemaking is toward reducing the inputs and especially sulphites, the development of While the trend in winemaking is toward reducing the inputs

Volatilome in grapevine leaves is defined by the variety and modulated by mycorrhizal symbiosis

Volatile organic compounds (VOCs) constitute a diverse group of secondary metabolites key for the communication of plants with other organisms and for their adaptation to environmental and biotic stresses. The emission of these compounds through leaves is also affected by the interaction of plants with symbiotic microorganisms, arbuscular mycorrhizal fungi (AMF) among them [1]. Our objective was to know the concentration and profile of VOCs emitted by the leaves of two grapevine varieties (Tempranillo, T, and Cabernet Sauvignon, CS, grafted onto R110 rootstocks), inoculated or not with a consortium of five AMF (Rhizophagus irregularis, Funneliformis mosseae, Septoglomus deserticola, Claroideoglomus claroideum and C. etunicatum).

Influence of harvest time and withering length combination on reinforced Nebbiolo wines: phenolic composition, colour traits, and sensory profile

Sforzato di Valtellina DOCG is a reinforced dry red wine produced in the mountain area of Valtellina alpine valley (North Italy), using ‘Nebbiolo’ grapes that undergo a withering process. This process impacts on the grape composition due to a sugar concentration and changes in secondary metabolism influencing volatile organic compounds (VOCs) and polyphenols.

Biosynthetic evolution of galloilated polyphenols in Tannat grapes during ripening, potential applications of grape thinning

Galloylated flavan-3-ols are a class of polyphenolic compounds present in various plants, including grape seeds. These compounds are formed through the condensation of flavan-3-ols, such as catechins, although the precise mechanism by which gallic acid is incorporated into the molecule remains unclear.