Veraison, the wonderful transformation of the grape

With the evolution of viticulture, a set of fundamental terms and concepts has been developed to understand the different processes that determine the final quality of the wine. Among these terms is the “veraison”, a crucial stage in the life cycle of the vine.
Veraison describes a specific phase in the development of the grapes, in which they undergo color changes and begin to ripen. This period acquires crucial importance, since significant transformations take place in the characteristics of the grape, such as colour, aroma and flavor, elements that will determine the quality of the wine.
In its early stages, the grapes are green and small, with low sugar levels and high acidity. This situation is due to the high concentration of chlorophyll present in the grapes. As the veraison process progresses, the grapes grow and accumulate water and sugars, while their acidity decreases. The skin of the grapes becomes thinner and changes color, the grapes turning from green to a darker color, such as red or purple in the case of red grapes, or golden yellow in white grapes.
The color changes that occur during veraison are a consequence of the presence of polyphenols, specifically anthocyanins in red varieties and carotenoids in white varieties. These polyphenols are also responsible for the sensations of astringency and bitter taste present in wine. At this stage, the aroma that characterizes each grape variety also develops.
In addition to the color change, veraison also entails changes in the chemical composition of the grapes. During this stage, the sugar levels in the grapes increase due to the accumulation of sucrose and glucose. At the same time, the acids present in the grapes, such as malic acid, begin to decrease, contributing to a decrease in the total acidity of the must. These changes in sugar and acid levels are crucial in determining the balance and final flavor of the wine.

Veraison also marks the beginning of the accumulation of aromatic compounds in the grapes. As the grapes ripen, they develop a variety of aroma compounds, such as esters, alcohols, and terpenes, which contribute to the characteristic flavors and aromas of the wine. Choosing the optimal moment for the harvest, which generally occurs after veraison, is essential to capture these aromatic compounds at their peak and guarantee the aromatic quality of the wine.
Veraison does not occur simultaneously for all the grapes in a bunch or vineyard. Different factors influence it, although the most decisive is the climate, but also the temperature, sun exposure, the grape variety, and the terroir. In general, veraison can last from one to four weeks, during which winegrowers closely monitor the evolution of the grapes. During this period, it is crucial to maintain a proper balance in the vineyard, ensuring adequate sun exposure, controlled irrigation, and good management of diseases and pests that can affect the grapes.
At veraison, they also evaluate the phenolic maturity of the grapes, the development of the different components of the grape that influence the structure and flavor of the wine, such as tannins. The texture, flavor and mouthfeel of the wine are highly dependent on the phenolic maturity of the grapes during veraison, a wonderful stage of change that will be crucial in determining the quality of the wine.