Astringency sub-qualities of red wines and the influence of wine-saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication.

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Do yeast lees always stimulate wine malolactic fermentation?

The use of non-Saccharomyces yeast together with S. cerevisiae in winemaking is a current trend. Apart from the organoleptic modulation of the wine, the composition of the resulting yeast lees is different and may thus impact malolactic fermentation (MLF). Yeasts of Saccharomyces cerevisiae, Torulaspora delbrueckii and Metschnikowia pulcherrima were inactivated and added to a synthetic wine. Three different strains of Oenococcus oeni were inoculated and MLF was monitored. This is the first study of MLF with different O. oeni strains in the presence of S. cerevisiae and non-Saccharomyces yeast lees to report a strain-specific interaction between them.

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Mycotoxins in red wine: Occurrence and risk assessment

Mycological contamination of food products is a common problem in the food industry, associated with implications for consumer health. Red wine is regarded as an alcoholic beverage with health benefits, notably for the circulatory system. However, in spite of its health-promoting properties, it can also be a source of toxic substances. Wine is a documented source of ochratoxin A, which is one of the ubiquitous, highly toxic secondary metabolites produced by filamentous fungi. It is the only mycotoxin for which a regulatory maximum level in wine has been established. There are no legal regulations on the content of other mycotoxins in wine, as a product with an increased risk of mycological contamination, and so their levels are not monitored. The aim of this study was to determine the concentrations of ochratoxin A (OTA), deoxynivalenol (DON) as well as T-2 and HT-2 toxins in dry red wines.

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What do you know about grapevine epigenetics? Results from Malbec, the star Argentinean variety

Clonal selection and vegetative propagation determine low genetic variability in grapevine cultivars, although it is common to observe diverse phenotypes. Environmental signals may induce epigenetic changes altering gene expression and phenotype. The range of phenotypes that a genotype expresses in different environments is known as phenotypic plasticity. DNA methylation is the most studied epigenetic mechanism, but only few works evaluated this novel source of variability in grapevines. In the present study, authors analyzed the effects on phenotypic traits and epigenome of three Vitis vinifera cv. Malbec clones cultivated in two contrasting vineyards of Mendoza, Argentina

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How much do we currently know about the relationship between grape and wine phenolics and cell wall material?

The present post summarizes a review that relates the last decade’s findings on the relationship between phenolics and polysaccharides from grapes, throughout the entire winemaking process up to evaluating the impact of their relationship on the red wine sensory perception. The combination and interconnection of the most recent research studies, from single interactions in model wines to the investigation of the formation of complex macromolecules, brings the perfect story line to relate the relationship between phenolics and polysaccharides from the vineyard to the glass. Grape pectin is highly reactive toward grape and grape derived phenolics. Differences between grape cultivars or changes during grape ripeness will affect the extractability of these compounds into the wines. Therefore, the nature of the grape components will be crucial to understand the subsequent reactions occurring between phenolics and polysaccharide of the corresponding wines. It has been demonstrated that they can form very complex macromolecules which affect wine color, stability and sensory properties.

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Do we really understand what experts tell us about wine?

Expert wine tasters have a greater ability than non-experts to discriminate between and evaluate the sensory properties of wine. In this study the authors explore non-experts’ understanding of a set of 64 terms which are frequently used as descriptors of the sensory properties of wine. The results reinforce the idea that when people describe wine or convey information, there is a serious risk of misunderstandings occurring when experts communicate with standard consumers. This indicates a necessity for wine industries to invest in research aimed at ensuring that experts (e.g. sommeliers, oenologists or producers) refer to the same basic sensory dimensions relating to wine as standard consumers. The present paper aimed to raise the question of whether the dimension referred to by experts (in the present case relating to a wine’s body or its acidity, for instance) matches the dimension that non-experts think of. This study has shown that modelling these dimensions in terms of opposite poles (which is typical of some tasting scales used by experts) also works quite well for standard consumers.

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Understanding 21st Century Bordeaux Wines from Wine Reviews Using Naïve Bayes Classifier

Although wine has been produced for several thousands of years, the ancient beverage has remained popular and even more affordable in modern times. Among all wine making regions, Bordeaux, France is probably one of the most prestigious wine areas in history. Since hundreds of wines are produced from Bordeaux each year, humans are not likely to be able to examine all wines across multiple vintages to define the characteristics of outstanding 21st century Bordeaux wines. Wineinformatics is a newly proposed data science research with an application domain in wine to process a large amount of wine data through the computer. This post summarizes the results of a study carried out with the goal of this paper is to build a high-quality computational model on wine reviews processed by the full power of the Computational Wine Wheel to understand 21st century Bordeaux wines. The model build in this research can better distinguish outstanding and class 21st century Bordeaux wines. Results provides new directions in Wineinformatics for technical research in data science, such as regression, multi-target, classification and domain specific research, including wine region terroir analysis, wine quality prediction, and weather impact examination.

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Drought impacts on key secondary metabolites: new insights from grape berries to wines

This post reports the results of a study aimed to explore the impact of water deficit on the concentration of key flavour and phenolic secondary metabolites of wines. It was observed that drought-induced compositional changes to the grapes were transferred to the wines, with an increase in polyphenols and volatile organic compounds. However, the timing and the duration of the water stress in the field only heavily impacted the final wine composition with major metabolic modification when the severe water deficit started early and lasted over the entire season until harvest. This study highlights the positive role of a controlled water deficit on the composition of the wines in terms of secondary metabolites

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Vitis vinifera L. fruit diversity to select or breed varieties anticipating climate changes

The wine industry is facing critical issues due to climate changes since production is established on very tight Genotype × Environment interaction bases. While, some cultivation practices may reduce adverse effects of abiotic stresses on the vines, e.g., the use of irrigation to mitigate drought, the deleterious impacts of warming on fruit development are difficult to manage. Elevated temperature alters grapevine fruit growth and composition, with a critical increase of the sugars/organic acids ratio. Select grapes with improved metabolite balances to offset high temperature effects is a valuable option to sustain viticulture. Unfortunately, the lack of knowledge about the genetic diversity for fruit traits impacted by temperature impairs the design of breeding programs. This study aimed to assess the variation in berry volume, main sugars and organic acids amounts in genetic resources.

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