Veraison
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Véraison is a French term, but has been adopted into the English literature on viticulture. The official definition of véraison is "change of color of the grape berries." Véraison signifies the change from berry growth to berry ripening in grapevines.
[edit] Process
Many changes occur at veraison. Grape berries follow a double sigmoid growth curve. The initial phase of berry growth is a result of cell division and cell expansion. As berry growth of phase I slows this is termed the Lag phase. The lag phase is not a physiological growth stage, but an artificial designation between the two growth periods of grape berry development.
Degradation of Malic acid results in a decrease of berry titratable acidity. Grapes also possess a small amount of citric acid, but Tartaric acid is another dominant acid. Tartrate accumulates early in phase I of berry growth, while Malic acid accumulates at the end of phase berry growth.
Accumulation of hexose sugars (sucrose, fructose) is associated with the development of xylem cell discontinuities. The deposition of sugar into the berry depends on the level of leaf photosynthesis, the number of competing sinks on the vine and sugar importation. Herbaceous aromas are degraded. It is unknown whether the degradation of herbaceous aromas allows fruit aromas to be detected, or if fruity aromas develop later in berry ripening.
The berry also changes in color. Presumably chlorophyll is broken down. In White cultivars carotenoids are formed, while in red cultivars anthocyanins and xanthophylls are formed. The trigger of veraison is unknown, but veraison signifies the seed reaching maturity. However, seed maturity is unlikely to cause as seedless berries also proceed through veraison.
[edit] Other uses
Fête de la Véraison is a medieval festival held in the famous winemaking village of Châteauneuf-du-Pape.
