The importance of monitoring the quality of grapes during the ripening phase

THE DYNAMICS OF MATURATION

As the growing season progresses, the monitoring of the grape quality becomes fundamental to define actions to reach production and oenological objectives.

Starting from veraison, several processes begin within the bunch leading to the complete technological, phenolic and aromatic maturation of the grapes. The accumulation of solutes inside the grape (mainly glucose and fructose) is followed by the increase in volume consequent to the greater mobilization of water inside the grape. The increase in the glucose and fructose content occurs mainly at the expense of malic acid and partially of tartaric acid. Despite the dynamics of maturation is influenced by genotype and climate, agronomic management may influence this process. The succession of vintages with fluctuating climatic conditions has made wine operators aware of the consequences of climate change on the quantity and above all on the quality of the grapes which will then be vinified.

Temperatures above the seasonal average during the ripening phase can lead to a rapid degradation of malic acid and a consequent increase in the sugar content of the grapes. This aspect, despite ensures the achievement of optimal sugar levels in some grapes, can make it difficult to harvest grapes with a total acidity greater than 6-7 g / l, which are particularly necessary for grapes with white berry.

Otherwise, in dark berried grapes the excessive sugar accumulation in the grape can lead to difficulties in the winemaking phase due to the excessive alcoholic content. During the maturation, moreover, there is an increase in the pH, the value of which should not exceed 3.5 in order to guarantee chemical and microbiological stability to the wine....

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