On the Verge of Veraison

With our Maltese and Gozitan 2015 grape growing season in full swing, our grapes will enter their final stage of ripening in about 10-14 days’ time.

This colour change is referred to as ‘veraison’ and normally takes place some 40 – 50 days after fruit set. Veraison is where the young, immature grapes, which at this time of year have a very dark green color and a somewhat hard texture, will start to take on their natural color change due to the chlorophyll in the berry skin being replaced by anthocyanins (or carotenoids in white grape varieties). The berries will also start to soften and begin to accumulate glucose and fructose. The natural sugars and the volume will then start to increase and the acidity levels will start to fall, usually within 6 days from the start of veraison.

Visually the red varieties going through veraison are easier to see than the white varieties and one of the first red varieties to go through this colour change stage, here on the Maltese Islands, will be the Sangiovese variety. Approximately 10 days after that, bigger, later ripening reds like Cabernet Sauvignon and Syrah will go through the same changes.

This photograph of Delicata Sangiovese grapes taken is a good example of red grapes depicting the initial phase of veraison.

The onset of veraison does not occur uniformly among all berries, even within the same bunch. Typically the berries and clusters that are most exposed to the most warmth, on the outer extents of the leaf canopy, undergo veraison first, whereas the berries and clusters closer to the trunk and under the canopy shade itself will undergo it last.

In red grapes the colour change will be from green to red, the depth and exact colour of the red will depend on the variety itself. For example grape varieties like Cabernet Sauvignon, Syrah and Merlot will be almost black, whereas grapes such as Pinot Noir, Grenache and Sangiovese will be lighter and redder in comparison. In white grapes the colour change will go from a dark green to a kind of a yellowish green color (again depending on the variety) and the skins will become more transparent.