Red wine oxidation: oxygen consumption kinetics and high resolution uplc-ms analysis

When talking about wine, terroirs are never too far. The National Institute of Apellation d’Origine (INAO) defines it as a system inside of which interact a group of human factors, an agricultural production and a physical environment.

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.

The vast majority of our understanding of grapevine physiology is focused on the processes that occur during the growing season. Though not obvious, winter physiological changes are dynamic and complex, and have great influence on the survival and phenology of grapevines. In cool and cold climates, winter temperatures are a constant threat to vine survival. Additionally, as climate changes, grapevine production is moving toward more traditionally cool and cold climates, either latitudinal or altitudinal in location. Our research focuses on understanding how grapevines navigate winter physiological changes and how temperature impacts aspects of cold hardiness and dormancy. Through these studies, we have gained keen insight into the connections between winter temperature, maximum cold haridness, and budbreak phenology, that can be used to develop prediction models for viticulture in a changing climate.

Measurement of carbon isotope discrimination in berry juice sugars at maturity (δ13C) provides an integrated assessment of water use efficiency (WUE) during the period of berry ripening, and when collected over multiple seasons can be used as an indication of drought stress response. Berry juice δ13C measurements were carried out on 48 different varieties planted in a common garden experiment in Bordeaux, France from 2014 through 2021 and were paired with midday and predawn leaf water potential measurements on the same vines in a subset of six varieties. The aim was to discriminate a large panel of varieties based on their stomatal behaviour and potentially identify hydraulic traits characterizing drought tolerance by comparing δ13C and hydroscapes (the visualisation of plant stomatal behaviour as a response to predawn water potential). Cluster analysis found that δ13C values are likely affected by the differing phenology of each variety, resulting in berry ripening of different varieties taking place under different stress conditions within the same year. We accounted for these phenological differences and found that cluster analysis based on specific δ13C metrics created a classification of varieties that corresponds well to our current empirical understanding of their relative drought tolerances. In addition, we analysed the water potential regulation of the subset of six varieties (using the hydroscape approach) and found that it was well correlated with some δ13C metrics. Surprisingly, a variety’s water potential regulation (specifically its minimum critical leaf water potential under water deficit) was strongly correlated to δ13C values under well-watered conditions, suggesting that base WUE may have a stronger impact on drought tolerance than WUE under water deficit. These results give strong insights on the innate WUE of a very large panel of varieties and suggest that studies of drought tolerance should include traits expressed under non-limiting conditions.

With wine fraud, being a widespread problem [1], the need for more sophisticated and precise analytical methods of its detection remains ever persistent.