Delicata Sangiovese grapes in the initial phase of veraison.

Grapes are entering their final stage of ripening in about 10 to 14 days’ time, as the Maltese and Gozitan 2015 grape-growing season gets into full swing.

This colour change is referred to as ‘veraison’ and normally takes place some 40 to 50 days after fruit set.

Veraison is where the young, immature grapes, which at this time of year have a very dark green colour and a somewhat hard texture, will start to take on their natural colour 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 six days from the start of veraison.

Visually, the red varieties going through veraison are easier to see than the white varieties. One of the first red varieties to go through this colour change stage in 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.

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 will change from green to red, with the depth and exact colour of the red depending on the variety itself. For example, grape varieties like Cabernet Sauvignon, Syrah and Merlot will become almost black, whereas grapes such as Pinot Noir, Grenache and Sangiovese will be lighter and redder in comparison.

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