Everyone has seen them – beautiful, ripened grape bunches ready for the harvest. Those beautiful bunches that are metaphorically the fruits of a miracle which later become that nectar we all know as wine. But beauty like this is not born by chance, but instead takes dedication, commitment and professionalism.
Long before grapes are harvested and ready for vinification, they go through quite a complex growth process which starts right after the first winter frosts. The growth stages can be grouped into the following stages – fruit set stage, veraison stage and the ripening stage.
The first stage is the fruit set stage, also referred to as the “herbaceous growth” stage since the grape bunch is still green and unripe in this phase. The grapes accumulate acid which can be found in the must. Sugars are few in this stage, only useful enough synthesize the plant metabolism in order to grow the fruit.
The second stage is the veraison stage where the grape begins to take on most of its distinctive features. The grape becomes translucent and elastic, pigments begin to take on more shape and sugars begin to accumulate. The bunch begins to take on the color they will have once harvested.
The third and final phase of grapes is that of maturation. The grapes swell until they assume their unique characteristics with the right balance of sugars and acid. This is the step where it is vital for an oenologist to distinguish the difference between a physiological maturation from a technological maturation.
In agriculture, a fruit is said to be mature when its seed can be germinated. Grapes are no exception. From a physiological point of view, the grapes are already ripened at the second stage (veraison), when they begin to form and assume their typical colors – red or white. Harvesting a grape in this phase would be foolish since their seed cannot yet be germinated and the fruit quality has not yet reached an optimal balance between sugars and acids – the kind we typically taste in a glass of wine. If wine is made with grapes that are in this stage, the wine quality would be extremely acidic and almost undrinkable.
This is why the “technological maturity” of grapes corresponds to the next, and third phase of the process where berries metabolize aromas and pigments. In simple terms, the grapes will have finally finished their lifecycle, reaching their height of organoleptic characteristics and its highest balance between acid and sugar. The harvest is then ready to bring to the cellar and pour into wine presses.
Grapes are ready for harvest when their level of acid is lowered and level of sugar is raised just until the level of over-ripening. If grapes reach a level of over-ripening, the sugar level will rise exponentially which makes for dessert wines and fortified wines.