3.1.2.b Maturity characterization

Characterising the ripeness of the pulp

When tasting the berries, the easiest place to start is by studying the pulp. Tastings are often carried out from a few weeks to a few days before the harvest, the berries are almost fully ripe and the pulp may already be very juicy.

One of the ways to determine if the pulp is ripe is to analyze its adherence to the skin and seeds. If the pulp adheres to the skin and seeds, it means that the fruit is not fully ripe. On the other hand, if the pulp easily detaches from the skin and seeds, there is a good chance that the berry is approaching or has already reached ripeness. Texture alone is not enough to characterize the berry's state of ripeness; examining aromatic parameters can provide further information on the berry's aromatic expression. We must then ask ourselves if the berry expresses vegetal, fresh fruitiness, ripe fruitiness etc. on the palate.

Certain aromatic precursors are odourless at the time of tasting and only appear once alcoholic fermentation has begun. Monitoring the aromatic intensity during tastings can guide the winegrower in determining the aromatic profile that they wish to give to their wine, although this can still vary greatly during vinification. The sugar/acid balance on the palate remains the main index to assess during berry tasting. For this purpose, a scale ranging from too acidic to too sweet can be used to assess the grapes' sugar/acid balance.

Characterising the ripeness of the skin

The textural maturity of the skins can also be determined by tasting. Two different criteria can be applied:

• Skin thickness: As maturity progresses, the skin tissue becomes thinner. There are two ways to assess this: first, evaluation while chewing with a scale going from very thick to very thin and second, the use of a penetrometer (measuring the force necessary to pierce the skin). Thickness plays an important role in extractability and can also vary according to the characteristics of the grape variety and the vintage.

• Skin permeability: As maturity progresses, the berry's skin breaks down, enabling good skin dilaceration in the mouth. There are two ways to determine the degree of permeability: mastication and the IPP (Skin Permeability Index).

Texture variation (dilaceration, thickness, firmness of the berry) would appear to be related to variation in the extractability of phenolic compounds, particularly anthocyanins, during berry ripening. Tasting also allows us to qualify the phenolic and aromatic ripeness of the skin:

• Progression in maturity translates into a quantitative evolution of the anthocyanin and tannin content on one hand and their qualitative evolution from an organoleptic point of view. The tannins are less vegetal, and astringency is reduced, which also facilitates extractability through a better diffusion of these phenolic compounds during vinification.

• The skin's acidity can be a relevant factor, but is taken into account less often. Like the study of the pulp, the flavours (herbaceous, vegetal, fresh fruit, ripe fruit, etc.) and their intensity are very important when deciding on a harvest date.

It is possible and even common to reach technological maturity before phenolic maturity. This is determined by weather conditions during the vintage and the potential sugar accumulation. Each winegrower has to decide the best balance for their wine.

Characterising the ripeness of the seeds

The seeds are the third and final part of the berry to be tasted. As with the pulp and the skin, the seeds can provide a lot of information. The first thing to study is their colour. The greener they are, the less ripe they are. Conversely, the browner they are, the more they have lignified and are therefore ripe.

Then, once when they are brown, their adherence to the pulp and their crushability can be assessed (before they become brown, they are very bitter and difficult to taste). The more difficult they are to crush, the more advanced the state of ripeness.

When the seeds are too green, the associated wine can be characterized by an overly reactive tannic structure, which is less pleasant on the palate with an elevated perception of astringency. Methods to determine the seeds' tannic quality and their optimal maturity are not very well developed, long and expensive. At present, only the SM% (seed maturity) determined by the Glories method or the tasting of the seeds provide some indication.