Fertility assessment in Vitis vinifera L., cv. Alvarinho

A part, at least, of red wines fruity expression may be explained by perceptive interactions involving particularly various substituted ethyl esters and acetates present at concentration far below their olfactory threshold, specifically thanks to synergistic effects. Wine sensory perception is directly linked to the stimulation of the taster at the level of olfactory epithelium by volatiles. These compounds are liberated from the matrix to the atmosphere, and will then be smelt. From a physico-chemical point of view, these volatiles ability to be released may be evaluated by their partition coefficients, which correspond to the volatile concentration ratio between the liquid and gas phase. Our goal is, through these coefficients determination, to assess if volatile matrix composition is able to impact the volatility of some compounds, and then explain sensory perception, i.eto evaluate what is called the pre-sensorial level impact.

When considering the application of a systemic approach to assess the intrinsic complexity of agricultural production, the following question immediately arises

The traditional methods of grape extraction of enochemical compounds use very often mechanical energy by pistons such as the pigeage or mechanical energy produced by must (delestage, pumping over). Recent trend by winemaker is trying to introduce in the fermentation tank, whole berry grape to avoid even minimal oxidation. Unfortunately, the use of the traditional mechanical techniques aforementioned, very often do not guarantee the optimal extraction with residual sugars in the marc. Use of resonance waves (airmixingtm) and a slight overpressure by CO2 (adcftm) permit to work on whole berry guaranteeing the perfect extraction.

The consequences of the global climate change in the vitiviniculture are revealed as a gap between phenolic and technological grape maturities, higher grape sugar concentration that leads to high wine alcohols levels, lower acidities and high pH values, among others. The unbalanced phenolic maturity caused in this scenario leads to harsh astringency and to instable colour of wines. Previous studies have reported that the addition of yeast mannoproteins (MPs) to wines may have positive effects on these two organoleptic properties due to their capability to interact with wine polyphenols [1]; however, studies about the effect of the pH on these interactions have not been carried out so far.

Spatial variability of vine productivity in winegrapes is important to characterise as both yield and quality are relevant for the production of different wine styles and products. The objectives were to understand how patterns of variability of Cabernet Sauvignon fruit composition changed over time and space, how these patterns could be characterised with indirect measurements, and how spatial patterns of the variation in fruit compositional attributes can aid in improving management. Prior to the 2017 vintage, 125 data vines were distributed across each of four vineyards in the Lodi American Viticultural Area (AVA) of California. Each data vine was sampled at commercial harvest in 2017, 2018, and 2019. Yield components and fruit composition were measured at harvest for each data vine, and maps of yield and fruit composition were produced for eight ‘objective measures of fruit quality’: total anthocyanins, polymeric tannins, quercetin glycosides, malic acid, yeast assimilable nitrogen, β-damascenone, C6 alcohols and aldehydes, and 3-isobutyl-2-methoxypyrazine. Patterns of variation in anthocyanins and phenolic compounds were found to be most stable over time. Given this relative stability, management decisions focused on fruit quality could be based on zonal descriptions of anthocyanins or phenolics to increase profitability in some vineyards. In each vineyard, dormant season pruning weights and soil cores were collected at each location, elevation and soil apparent electrical conductivity surveys were completed, and remotely sensed imagery was captured by fixed wing aircraft and two satellite platforms at major phenological stages. The data collected were used to develop relationships among biophysical data, soil, imagery, and fruit composition. The standardised and aggregated samples from four vineyards over three seasons were included in the estimation of ‘common variograms’ to assess how this technique could aid growers in producing geostatistically rigorous maps of fruit composition variability without cumbersome, single season sampling efforts.