Relationship between chemical parameters of tannins and in-mouth attributes of grape phenolic fractions

The Champagne vine-growing region has played a pioneering role in the delimitation of appellations of origin (AOC). The implementation of the Act of July, 22nd 1927 has led to drawing up lists of vine plots based on the criterion of vine cultivation antecedence.

The application of sensors in viticulture is a fast and efficient method to monitor grapevine vegetative, yield and quality parameters and determine their spatial intra-vineyard variability. Molecular analysis at the gene expression level can further contribute to the understanding of the observed variability by elucidating how pathways responsible for different grape quality traits behave in zones diverging for one or the other parameter. The intra-vineyard variability of a Cabernet Sauvignon vineyard was evaluated by a standard Normalized Difference Vegetation Index (NDVI) mapping approach, employing UAV platform, accompanied by detailed ground-truthing (e.g. vegetative, yield, and berry ripening compositional parameters) that was applied in 14 spots in the vineyard. Berries from different spots were additionally investigated by microarray gene expression analysis, performed at five time points from fruit set to full ripening.

The mechanisms behind thiol precursor accumulation in grapes remain incompletely understood, nor are the ways in which they can be improved by agronomic practices. A six-year field trial studied the physiological response of the Swiss white cultivar Vitis vinifera Arvine, rich in varietal thiols and precursors, to canopy management, i.e. leaf removal and canopy height.. Five treatments were set up in a randomized block design to assess the impacts of 1) pre-flowering LR (i.e. pre-flowering or full-flowering stages) and 2) compensating for the leaf area removed in the cluster zone by increasing the trimming height (i.e. 100 or 150 cm canopy height), compared with a non-defoliated control treatment.
Intensive pre-flowering LR severely reduced yield potential (–47% on average) and reduced the concentration of 3-mercaptohexanol precursors (P-3MH) in the must (–21%; p-value < 0.10).

Sulfur dioxide (SO2) is used in winemaking due of its antioxidant, antioxydasic and antiseptic properties. Excessive amount of SO2 can negatively impact wine sensory perception and be detrimental for health. Agri-food industries are more transparent towards consumers concerning addition of sulfites, and oenology is no exception in this clairvoyance. As a consequence, the increase of consumers preference for wine with low or absent of sulfites addition is notorious. In this context, the impact of low/zero sulfites winemaking process on the microbial community should be evaluated. Moreover, microbial agents corresponding to bioprotective cultures represent a growing interest as an alternative to sulfites preservation in the early stages of vinification. However, scientific studies conducted to demonstrate their real effect are almost rare.

During red wine ageing or conservation, color and taste change and astringency tends to reduce. These changes result from reactions of flavan-3-ols and/or anthocyanins among which condensation reactions with acetaldehyde are particularly important. The full characterization of these reactions has not been fully achieved because of difficulties in extracting and separating the newly formed compounds directly from wine. Model solutions mimicking food products constitute a simplified medium for their exploration, allowing the detection of the newly formed compounds, their isolation, and their structure elucidation.