Reduction or conversion of the acids contained in the wine by various cellar-technical measures. This is especially necessary in bad wine years when the grapes have not reached a sufficient degree of ripeness. According to EU law, this is generally permitted for fresh grapes, grape must, partially fermented grape must, young wine and wine. However, this depends on the wine-growing zone.
Partial deacidification (but not acidification) is permitted for wine-growing zone A(Germany, excluding the Baden wine-growing region) and wine-growing zone B (German Baden and Austria). A high acidity content in the grape must with a low pH value results in a purer fermentation, but is very useful above 12 g/l. Grape musts are generally deacidified to about 9 to 10 g/l.