4.1.2.c Harvest correction

Chaptalization

This practice consists of enriching the must with sugar in order to increase the potential ABV. Sucrose is the main ingredient used.

This practice is highly regulated and is only performed for vintages where the potential ABV is insufficient. Each year chaptalization is authorized or not by an appellation decree with a maximum legal increase of the ABV defined by the appellation. Chaptalization can only be carried out after the decree's publication.

Generally, it is considered that 16.83 g/L of sugars are needed to produce 1% vol of alcohol or 1.683 kg/hL.
Q=(desired PABV- initial PABV) × 1.683 × V

Where V is the volume of must in hL and Q is the quantity of sucrose to add in kg.
Due to climate change, this practice is becoming less common.

Acidification

Acidification consists of adding tartaric or lactic acid to either the must or the wine. Outside of organic regulations, malic acid and acidification using an electromembrane treatment are also authorized.
What are the current regulations?
Acidification and chaptalization are mutually exclusive.
Acidification is subject to strict regulations in Europe. Wine-growing areas are classified into different categories depending on the climate.
Some are only allowed to deacidify, others to only acidify and others can do both depending on the year. Obviously, acidification and deacidification are mutually exclusive.
Acidification is subject to declaration and the maximum legal dose is 150 g/hL for musts and 250 g/hL for wine regarding tartaric acid.

When should acidification be carried out?

Acidification can be carried out at the beginning of the harvest, on the must or following vinification.
Acidification of the must allows better tartaric acid assimilation on an organoleptic level. However, at this stage, the fermentation environment is not stable and it is very difficult to predict the total value that will end up being added. Acidification of wine leads to a significant precipitation of tartaric salts because at this stage the environment is saturated with tartaric acid/potassium complex.
There is therefore no good or bad solution.
As a rule of thumb, tartaric acid is mainly added to musts and lactic acid to wines.

What acid(s) should be added?

The choice of acid will depend on the winemaker's objective. Tartaric acid is the most effective for modifying pH. Tartaric acid increases the wine's vivacity and firmness. In a potassium-saturated environment, the addition of tartaric salts is not ideal. Lactic acid is milder. Moreover, its salification with potassium remains soluble in the wine. However, its impact on the pH is reduced.
In the case of acidification of wine, tests are easy to implement and a combination of the two acids is possible.