Acidity is one of the most important components in grapes and wine, and is also easily quantified. The wines present attractive qualities in their taste balance between the sensations of acidity, sweetness, bitterness and even astringency in red wines. The average temperature in the vineyard during the ripening of the grapes strongly influences the acid balance of the future wine. Average temperatures above 21 ° C in the last month of ripening lead to a decrease in the malic acid content of the grapes, confirmed by the determination of the total acidity as well as a higher pH value. (1) This, along with the enrichment of the sugar content, is one of the first consequences of global warming, particularly in the Mediterranean area.

A sufficient level of acidity increases the perception of freshness in the wine, limits the risks of microbial development, by reinforcing, in particular the effectiveness of sulfur dioxide (sulphites).

The acidification of wine, by adding tartaric acid, malic acid or other acids, is subject to regulation. It can be done via different means (addition of acids, fermentation inoculation of yeasts modulating the acid component), including through the subtraction of cations (potassium) in wines by different processes. The addition of acid is generally recommended in mash. Other processes can be used on wines, depending on the regulations in force and labeling (eg organic).
Regulations vary from country to country, but the main additives permitted for acidification are tartaric acid, citric acid and malic acid.

Authors: Maddy Tintinger (INRAE), Philippe Darriet (ISVV)

(1) https://irrec.ifas.ufl.edu/flcitrus/pdfs/short_course_and_workshop/citrus_flowering_97/Goldschmidt-Effect_of_Climate_on_Fruit_Development.pdf