🍷 Deacidification

Deacidification is lowering the excess acidity of wine or must so that it tastes softer and more balanced. It is needed above all in cold years: the grapes do not ripen fully, too much acid remains in them, and the wine turns out harsh.

According to the OIV, deacidification lowers titratable acidity and raises pH. Wine loses part of its acid on its own: tartaric acid drops out as tartrate deposits, and bacteria turn sharp malic acid into softer lactic acid. Acidity can also be lowered by blending with a less acidic wine, by chilling, or by ion-exchange treatment.

For chemical deacidification, neutral potassium tartrate, potassium bicarbonate or calcium carbonate is added. These substances bind part of the acid into salts that then settle out. The OIV requires at least 1 g/l of tartaric acid to remain in the wine afterwards, and chemical deacidification is not combined with chemical acidification.

Malolactic fermentation is started at the end of alcoholic fermentation, keeping the wine at about 18 °C and with little sulphur dioxide, because lactic acid bacteria are sensitive to it. In the EU wine may be deacidified by at most 1 g/l, expressed as tartaric acid, and the same product may not be both acidified and deacidified.

Why it matters to you. Deacidification explains why a wine from a cold year is not necessarily sour: the winemaker can soften the taste, but only within the rules. Too much intervention makes wine flat, so the OIV stresses that wine must not lack acidity after deacidification.