Veraison

In viticulture (grape-growing), veraison is the onset of ripening. The term is originally French (véraison), but has been adopted into English use. The official definition of veraison is "change of color of the grape berries". Veraison represents the transition from berry growth to berry ripening, and many changes in berry development occur at veraison.

Process

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.

Post-veraision, fruit acidity decreases due to degradation of malic acid. The degradation of malic acid during ripening makes tartaric acid the predominant acid; grape berries also possess a small amount of citric acid. Tartaric acid accumulates early in phase I of berry growth, while malic acid accumulates at the end of phase I berry growth.