Acidification

What is Acidification? Acidification is the winemaking practice of adding food-grade acids to must or wine to raise total acidity and lower pH. The primary acid used is tartaric acid, the same acid that occurs naturally in grapes, with malic and lactic acids playing smaller, regulated roles. The technique is most commonly applied in warm-climate regions, where grapes ripen with high sugars and ample potential alcohol but arrive at the cellar with naturally low acidity. As the opposite operation of deacidification, it is one of the core tools winemakers use to bring a wine into balance.

How and When It Is Done

Tartaric acid is the acidifier of choice because it is stable, naturally present in grapes, and resistant to microbial breakdown. Malic and lactic acids are permitted in some cases, while citric acid is treated very differently — under EU rules, it cannot be used as an acidulant for wine and is only allowed in small amounts to strip out excess iron and copper. Citric acid additions must also wait until after primary fermentation is complete, because yeast can convert it into acetic acid, pushing the wine toward a vinegary character.

Timing matters as much as the choice of acid. Tartaric acid is most often added after fermentation, but it can also go into the must when pH is higher than about 3.5. Earlier additions tend to integrate more seamlessly, while acid added during blending or aging is more perceptible on the palate. Across all of this, most finished wines settle into a pH range of roughly 2.9 to 3.9, and total acidity and pH do not move in a strict linear relationship — small pH shifts can reflect quite different acid loads.

Rules and Regional Context

European Union regulation sets clear ceilings on how much acid can be added. Under Regulation EU 1308/2013, the maximum addition is 1.5 g/L for must and 2.5 g/L for wine, expressed as tartaric acid equivalents. When both must and wine are acidified, the cumulative net increase may not exceed 54 meq/L, equivalent to 4 g/L as tartaric acid. Other additives such as ascorbic acid (capped at 150 mg/L) and sorbic acid (capped at 200 mg/L) play a preservative role and are not acidifiers in the regulatory sense.

Geography shapes the practice. Acidification is typical of warm-climate regions where sugar accumulation outpaces acid retention on the vine. In many traditional cool-climate EU appellations the procedure was historically banned or restricted, with rules tightened or relaxed by wine zone (A through C) according to climate. In Wine Zone A, where grapes often arrive with sharper acidity, deacidification is permitted instead — with no limit on musts but a maximum of 1 g/L (as tartaric acid) for finished wine.