The veraison process is the change of colour of the grapes that occurs when the fruits grow and they go from green to red or yellow, depending on the grape variety.

In this period the grapes are green and hard to the touch. They have very little sugar and are high in organic acids: after about 40-50 days they reach their full maturity until they’re ready to be harvested.

This colour changing is due to the chlorophyll in the grape skin being replaced by anthocyanins (red wine grapes) and by carotenoids (white wine grapes). In a process known as engustment, the grapes start to soften as they build up sugars. Within six days from the start of veraison, the grapes begin to grow significantly as they accumulate glucose and fructose and malic acid falls.