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IVES 9 IVES Conference Series 9 Determination of the maturity status of white grape berries (Vitis vinifera L. cv Chenin) through physical measurements

Determination of the maturity status of white grape berries (Vitis vinifera L. cv Chenin) through physical measurements

Abstract

[English version below]

La véraison, stade intermédiaire du développement de la baie de raisin, correspond au début de la maturation. Aux modifications de coloration de la pellicule sont associées une perte de fermeté, une diminution de l’acidité et une augmentation des teneurs en sucres et pigments ainsi que du volume de la baie. Le stade de véraison des cépages blancs reste difficile à apprécier visuellement. Son évaluation par palpation est subjective et donc sujette à caution. Une méthode non destructive d’analyse de la fermeté des baies (Cabernet franc) a été mise au point dans une précédente étude, utilisant des tests de compression. Cette méthode, qui permet de relier la fermeté à la composition biochimique a été étendue au Chenin. Des baies issues de deux parcelles bien caractérisées au plan des facteurs naturels du milieu (géo-pédologie) et du comportement de la vigne, ont fait l’objet de tests de compression et d’analyses biochimiques au cours de 10 prélèvements successifs couvrant la période 2 semaines avant véraison jusqu’à 2 semaines après véraison. Les résultats montrent que, comme dans le cas du Cabernet franc, le taux de compression à 20% de la hauteur de la baie ainsi que les classes de pression utilisées sont pertinentes. La méthode permet de déterminer avec précision une date de mi-véraison physique, de mettre en évidence le niveau d’hétérogénéité des baies au sein de chaque lot et des différences de précocité entre parcelles. Par ailleurs, une bonne corrélation entre la perte de fermeté des baies et leurs teneurs en sucres et acide malique peut être obtenue dès que le processus de véraison est amorcé. Ces résultats permettent d’envisager le suivi « in situ » de l’évolution de la maturation des baies, de manière dynamique et non destructive.

Veraison represents an intermediate stage in development of grape berries, coinciding with the onset of the maturation process. The change in skin coloration is associated with a loss of firmness, a reduction of acidity and an increase in sugar and pigment contents, as well as berry size. For white berries, veraison is difficult to determine on a visual basis. Its evaluation through finger pressure is too subjective to be used as a routine technique. In a previous work, compression tests realized with Cabernet franc berries allowed to develop a non destructive method to analyse the firmness of the berries in relation with their chemical composition ; this method is now extended to the Chenin variety. Samples of berries were taken from two experimental plots for compression tests and chemical analyses, at ten picking dates, from two weeks before veraison until two weeks after. The plots were chosen according to their geo-pedological characterisation and its consequences on the behaviour of the vine. Results indicated that the compression ratio of 20% of the berry diameter and the pressure classes determined for Cabernet franc were also accurate for Chenin. The method allowed to determine with precision the physical mid-veraison stage (loss of firmness for 50% of the berries) and brought to the fore the level of heterogeneity of berries and the differences between plots in terms of earliness. High correlations between berry firmness and both sugar and malic acid contents were obtained as soon as the veraison process initiated. These results will enable to follow in situ the evolution of the grape berry maturation, on a dynamic non destructive way.

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

G. Barbeau, Y. Cadot, F. Neau

INRA, Unité Expérimentale Vigne et Vin, 42, rue Georges Morel, BP 57, 49071 Beaucouzé cedex (France)

Contact the author

Keywords

Vitis vinifera, chenin, terroirs, firmness, heterogeneity, veraison, maturation

Tags

IVES Conference Series | Terroir 2004

Citation

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