Delicata Sangiovese grapes during the initial phase of veraison.

With the Maltese and Gozitan 2013 grape-growing season in full swing, our red grapes will be entering their final stage of ripening in about seven to 10 days’ time.

This stage is often referred to as ‘veraison’, which normally takes place some 40 to 50 days after fruit set.

Basically, veraison happens when the young, immature red grapes, which at this time of year have a very dark green colour and a somewhat hard texture, start to take on their natural colour due to the chlorophyll in the berry skin being replaced by anthocyanins – or carotenoids in white grape varieties.

One of the first red varieties to go through this colour change will be the Sangiovese variety.

Ten days after that, bigger, later-ripening reds like Cabernet Sauvignon and Syrah, will go through the same process.

The berries also start to soften to accumulate glucose and fructose. The natural sugars and the volume then start to increase and the acidity levels start to fall, usually within six days from the start 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 exposed to the most heat – 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, undergo this process later.

The colour of red grapes changes from green to red; the depth and exact colour of the red depends on the variety.

For example, grape varieties like Cabernet Sauvignon, Syrah and Merlot become almost black, where­as grapes such as Pinot Noir, Grenache and Sangiovese will be lighter and redder in comparison.

In white grapes, the colour changes from a dark green to a kind of a yellowish green (again depending on the variety) and the skins become more transparent.