The main consequence of high temperatures is the loss of acidity and the increase in the sugar level in the berries of the grapes, with the consequent increase in the alcoholic level in the final wine.
While the second consequence is more or less manageable from the date of harvest and good irrigation management, if available, the control of acidity appears more complex.
As we have said in a previous communication, controlling the microclimate of the bunch is one of the most effective viticultural techniques available to us. It is about preventing the direct incidence of the sun’s rays on the grapes through vigorous development of the plant’s leaf mass. This direct impact would mean a major increase in the temperature of the grape grain and consequently the metabolization (that is, consumption and extinction) of a good part of the natural acids of the grape and the loss of a good part of the aromatic potential.
It should be said that this operation is greatly facilitated by irrigation, moderate during the initial phase of the vegetative cycle and with a slight increase in the final phase of maturation. In dryland vineyards, fatally, the ability to influence the microclimate of the grapes is greatly diminished. The dryland situation with climate change is really critical and very uncertain, not only in terms of quality but viability.
In the Clos Pons winery we must continue to control acidity. Before resorting to the external addition of tartaric acid – a permitted practice and, let us remember, the majority acid in grapes and wine and, curiously, the exclusive acid of our fruit, does not exist in any other terrestrial fruit -, before resorting to this, as we said, in our case we have opted for a selection of fermentation yeasts that allow us to slightly increase the acidity level of the must and thus preserve a good balance with the alcohol, the basis of the quality of the whites.
In some of our Clos Pons whites we carry out a partial malolactic fermentation of the wine or a total malolactic fermentation of one of the members of the final coupage of the wine. As you know, malolactic fermentation – carried out by lactic bacteria – involves the transformation of malic acid, natural to grapes, a strong and hard acid, into lactic acid, soft and sweet. This is a practice that we have abandoned as it made the wine too flat. The presence of malic is basic for the relief and liveliness of the wine on our palate.
Martí Magriñá, Winemaker Clos Pons