 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 What is the best time to harvest grapes destined for withering? Ripeness and dehydration length affect phenolic composition of Nebbiolo grapes

What is the best time to harvest grapes destined for withering? Ripeness and dehydration length affect phenolic composition of Nebbiolo grapes

Abstract

AIM: Sfursat di Valtellina is a DOCG reinforced wine produced in Valtellina from partially withered red grapes of Vitis vinifera L. cv. Nebbiolo. The grape ripeness degree and the dehydration process strongly influence the physicochemical characteristics of grapes [1, 2, 3]. In particular, grape skin and seeds contain several classes of phenolic compounds strictly associated with red wine quality, which are significantly affected by these factors [4]. The aim of this research is to assess the combined influence of different ripeness levels and withering rates on the standard chemical composition and phenolic profile of winegrape in order to provide new insights and approaches to the management of withering, searching for the valorization of grape potentialities.

METHODS: During a two-year study (vintages 2019 and 2020) three binomials have been tested: early harvest/long withering (EL), medium-term harvest/medium-term withering (MM) and late harvest/short withering (LS). Grape samples of cv. Nebbiolo from two vineyards at different locations (Valtellina upper and lower valley) were harvested and placed into a typical ‘fruttaio’ dehydration room, following the wine type designation guidelines. Grape must composition, mechanical parameters and extractable phenolic profiles (total polyphenols, total anthocyanins, total flavonoids and methylcellulose tannin assay) of grape skins and seeds were studied before and after the withering process.

RESULTS: At the end of withering, EL thesis showed the highest values of sugars and acidity, and the lowest pH. The content of total polyphenols, flavonoids, and tannins in seeds showed a decreasing trend by leaving the grapes on the plant longer, whereas their impact increased considerably after withering with respect to fresh samples, due to berry dehydration. Instead, the skin phenolic compounds were less influenced by harvest period, but their concentrations on grape weight increased after withering. Skin extractable anthocyanins experienced a distinct trend for the two vineyards studied: their concentration increased in withered samples from the upper-valley vineyard and decreased in those from the lower-valley. The grapes mechanical properties may have influenced this aspect, as previously demonstrated [5]. Finally, the differences highlighted between the three binomials studied were more noticeable in vintage 2019 rather than in 2020, probably due to the higher rainfall in the final stage of grape ripening in vintage 2020.

CONCLUSIONS:

In this research, the combined effect of ripeness degree and withering process length have been studied. The results obtained shows that these two variables can be modulated according to the desired oenological objective. In general, early/medium harvest and long/medium withering gave the best results, particularly for seeds polyphenols, although the vineyard location and the weather conditions of the year influenced the withered grape phenolic characteristics.

DOI:

Publication date: September 16, 2021

Issue: Macrowine 2021

Type: Article

Authors

Giulia Scalzini

University of Torino, Italy,Maria Alessandra PAISSONI, University of Torino, Italy Simone GIACOSA, University of Torino, Italy Danilo DROCCO, Cantina Nino Negri, Italy Aldo RAINOLDI, Casa Vinicola Aldo Rainoldi, Italy Diego ORTIZ JACOB, University of Torino, Italy Giovanni BITELLI, University of Torino, Italy Susana RÍO SEGADE, University of Torino, Italy Vincenzo GERBI, University of Torino, Italy Luca ROLLE, University of Torino, Italy

Contact the author

Keywords

postharvest withered grapes, phenolic compounds, withering process, sfursat di valtellina, sforzato, reinforced wines, special wines

Citation

Mouthfeel effects due to oligosaccharides within a wine matrix

The mouthfeel of wine is one of the most important aspects of the organoleptic experience of tasting wine. In wine a great deal is known about certain compositional components and how they impact mouthfeel perception, such as phenolics. But there are other components where little is understood, such as oligosaccharides. Saccharides in general are found in very low concentrations with wine, especially compared to conventional foods. There is very little information about how oligosaccharides influence the mouthfeel perception of wine.

Hanseniaspora in wine-making: their genetic modification and potential role in acid modulation

Hanseniaspora spp. are one of the most common yeast isolates in vineyards and wineries and play an important role in wine-making.

Molecular cloning and characterization of UDP-glucose: furaneol glucosyltransferase gene from Japanese

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol) is an important aroma compound in fruits, such as pineapple and strawberry, and is reported to contribute to the strawberry-like note in some wines. Several grapevine species are used in winemaking, and furaneol is one of the characteristic aroma compounds in wines made from American grape (Vitis labrusca) and its hybrid grape, similar to methyl anthranilate. Muscat Bailey A is a hybrid grape variety [V. labrusca (Bailey) x V. vinifera (Muscat Hamburg)], and its wine is one of the most popular in Japan. The inclusion of Muscat Bailey A in the ‘International List of Vine and Varieties and their Synonyms’ managed by the ‘International Organisation of Vine and Wine (OIV)’ in 2013 has further fueled its popularity among winemakers and researchers worldwide.

Partitioning of seasonal above‐ground biomass of four vineyard-grown varieties: development of a modelling framework to infer temperature-rate response functions

Aims: Forecasting the biomass allocation among source and sinks organs is crucial to better understand how grapevines control the distribution of acquired resources and has a great meaning in term of making decisions about agricultural practices in vineyards. Modelling plant growth and development is one of prediction approaches that play this role when it concerns growth rates in response to variation in environmental conditions

Evaluating alternatives to cold stabilization in wineries: the use of carboximethyl cellulose, potassium polyaspartate, electrodialysis and ion exchange resins – the results after one year in the bottle

The tartaric stabilization of wines before bottling to avoid the precipitation of tartaric acid salts is an important and common step during wine production. The presence of precipitated salt crystals in bottle wines is detrimental for their quality and even a legal issue in some countries. Cold stabilization is the most common stabilization treatment. Although it has been shown to be effective, it has some significant disadvantages, mainly regarding losses of color and aromas and its high cost. Therefore, other products and methodologies are being introduced in the wineries for the replacement of this process. Some of these new techniques involve the reduction of the ions causing the insolubilization of tartaric acid while other are based in the formation of protective colloids or the inhibition of the crystallization of salts. In this study, white, rosé and red wines have been treated with carboxymethylcellulose, potassium polyaspartate and an ion exchange resin. The tartaric stability of the wines, together with the oenological, chromatic and sensory characteristics were studied after the wines had been stored during one year in the bottle. The results indicate that the use of carboxymethyl cellulose and potassium polyaspartate maintained the best the sensory and chromatic characteristics and the wine stability of the wines in comparison with an untreated control wine.