From grapes to sparking wines: Aromas evaluation in a vine-spacing

Dans la région des Coteaux du Layon, en Maine et Loire, l’effet terroir et son déterminisme sont étudiés dans le cadre de la production des vins liquoreux.
Ces vins sont le résultat d’une maturité poussée au delà de celle prévue par la nature afin de donner aux baies une teneur en sucre et en matière sèche très forte, pour mieux valoriser ces effets de la surmaturation, les baies sont récoltées selon la méthode des tries successives (Asselin et al, 1996). Ainsi, on ne récolte à chaque passage que les grains ayant atteint le niveau de concentration requis pour obtenir des vins à fort degré d’alcool avec des sucres résiduels.

The Douro Demarcated Region, in Northern Portugal, offers outstanding wines with unique characteristics. Due to the today’s globalized marketplace, local producers often need to further develop their cultivation techniques to remain competitive. The Association of Viticultural Development in the Douro Valley (ADVID) works as a unit of experimentation, offering services and training to meet the demands of the Douro’s vitiviniculturists.

Viticulture is facing two major changes – climate change and agroecological transition. In both cases, soil quality is seen as a lever to move towards a more sustainable viticulture. However, soil biological quality is little considered in the implementation of viticultural practices. Gascogn’Innov (2017-2022) is an Operational Group funded by the European Innovation Partnership for Agriculture. As such, it brings together winegrowers from the south-west of France, scientists, advisors and technicians, around a project focused on viticultural soil biological functioning and the design of technical routes more respectful toward soil heritage. To achieve this, the project aims to acquire references on the impact of viticultural practices on soil biology from a dynamic way, and to test a methodology to integrate information provided by the soil bioindicators to manage farming systems. A set of indicators of soil biological quality are evaluated in the project: microorganisms (bacteria and fungi abundance and diversity), fauna (abundance and diversity of nematodes and earthworms), physico-chemical characteristics, soil structure assessment and degradation rate of organic matter. Based on a network of 13 plots that have been subject to an initial diagnosis in 2017, several agronomical practices to restore soil fertility are experimented to redesign the cropping system (for instance plant cover, organic matter inputs, reduction of herbicides, mineral fertilizers). System redesign was made in collaboration by winegrowers and an interdisciplinary group of experts (agronomists, biologists). Several indicators are measured on vine and soil at each vintage to assess vine health and productivity. At the end of the project (2021), a final diagnosis was carried out. Gascogn’Innov allowed to create a regional database on the quality of wine-growing soils, which permitted to evaluate the effect of practices according to soil types. Especially, decreasing the intensity of tillage and increasing the duration and diversity of grass coverage tends to increase the abundance of all the organisms studied. This project confirmed the value of soil biological quality indicators to drive the sustainability of practices, but also highlighted the key-role of expertise, in both agronomy and soil biology, to help winegrowers understand and appropriate their soil quality diagnoses.

The peppery attribute is often used to describe the aroma of Syrah wines. Rotundone was identified as the main aroma compound responsible for these notes. A significant percentage of anosmic respondents to this molecule was reported in previous studies. However, in most cases, these anosmic respondents, formally tested through three-alternative forced choice (3AFC), frequently declare being able to perceive peppery notes in wines. The main objective of this study was to investigate how anosmic French producers from two different regions conceptualize the peppery notes in Syrah red wines, and how they link it to production practices in comparison with non-anosmic producers.

As observed in other grape varieties, Red Grenache juice contains low level of volatiles. The main flavor compounds are ” Iock up “as flavorless glycoconjugates which could generate at the wine pH volatile flavorants and constitute the varietal aroma of this cultivar.