Early colour change in McLaren Vale Shiraz has been seen. Vineyards that normally begin to change colour (begin veraison) around the 2nd - 5th of January have started colour change on the 25th of December.
Chardonnay and Verdelho are also softening and beginning to produce sugar.
Based on this he season is likely to be an early harvest this vintage.
Following fruit set, the grape berries are green and hard to the touch. They have very little sugar and are high in organic acids. They begin to grow to about half their final size when they enter the stage of veraison. This stage signals the beginning of the ripening process and normally takes places around 40-50 days after fruit set.
During this stage the colours of the grape take from - red/black or yellow/green depending on the grape varieties. This color changing is due to the chlorophyll in the berry skin being replaced by anthocyanins (red wine grapes) and carotenoids (white wine grapes). In a process known as engustment, the berries start to soften as they build up sugars.
Within six days of the start of veraison, grape berries begin to grow dramatically as they accumulate glucose and fructose and acids begin to fall.