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IVES 9 IVES Conference Series 9 Contribution à l’étude des relations entre des variables de fonctionnement des terroirs du Val de Loire et l’évolution des acides organiques des baies durant la maturation du raisin

Contribution à l’étude des relations entre des variables de fonctionnement des terroirs du Val de Loire et l’évolution des acides organiques des baies durant la maturation du raisin

Abstract

[English version below]

Dans les terroirs du Val de Loire, la précocité du cycle de la vigne et son alimentation en eau sont des variables de fonctionnement qui influent de manière importante sur la composition des baies à maturité. La présente étude aborde l’analyse du rôle de ces variables sur l’évolution des acides organiques des baies, constituants essentiels de la qualité des vins. La teneur en acide malique apparaît corrélée négativement à la précocité induite par le terroir ; la relation est meilleure en début de maturation qu’à maturité. Durant tout le cycle de la plante, des conditions climatiques favorables à une croissance soutenue semblent jouer un rôle positif sur la teneur en acide tartrique, mais certains facteurs climatiques sont responsables d’une combustion plus rapide de l’acide malique durant la maturation. L’évolution conjointe de ces deux acides organiques peut être appréciée au travers de deux rapports : acide tartrique/acide malique et acide tartrique/( acide tartrique + acide malique) encore appelé coefficient de maturation. En début de maturation, les valeurs de ces deux rapports sont en liaison avec le niveau de précocité des terroirs. Les écarts entre terroirs augmentent au cours de la maturation. A maturité, les différences observées varient du simple au quadruple selon le terroir et le millésime ; elles semblent imputables à la fois à la précocité et à la contrainte hydrique. Le rapport acide tartrique/acide malique discrimine mieux les terroirs que le coefficient de maturation.

In the terroirs of the Mid-Loire Valley, the precocity of the cycle of grapevine and its water intake regime are functionning variables which influence strongly berry composition at maturity time. The present study deals with the role of these variables on the evolution of organic acids, which are considered as major components of wine quality. The malic acid content is negatively correlated to the terroir-induced precocity; the relationship is better at the beginning of the maturation process than at its end. All the climatic factors which can enhance growth during all the cycle seems to favor a higher tartaric acid content, but some of them are also responsible for a quicker combustion of malic acid during maturation. The joint evolution of these two organic acids can be appraised through two ratios: tartaric/malic acid and tartaric/ [tartaric + malic] acid, the latter also known as the maturation coefficient. At the beginning of the maturation process these ratios appear to be mainly related to the level of precocity of the terroirs. The gap between terroirs increases during maturation. At maturity, the differences may vary from one to four, according to the terroir and the vintage; they seem to be due to both the precocity and the level of water stress. The tartaric/malic acid ratio is more discriminant than the maturation coefficient in terms of behaviour of the grapevine.

DOI:

Publication date: February 24, 2022

Issue: Terroir 2000

Type: Article

Authors

G. Barbeau, R. Morlat, C. Asselin, Y. Cadot

Unité de Recherches Vigne et Vin, Centre INRA d’Angers (France)

Keywords

terroirs viticoles, acides organiques, précocité, alimentation hydrique
viticultural terroirs, organic acids, precocity, water intake regime

Tags

IVES Conference Series | Terroir 2000

Citation

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