How is sparkling wine made?
Exogenous carbon ic acid (more precisely: the gas carbon dioxide, which then dissolves in the liquid in the form of carbonic acid) is added to the still wine after it is finished in a pressure tank(impregnation process). In this case, the gas does not come from wine production, but is usually technically produced. The end product must then be called "sparkling wine with added carbonic acid".
Endogenous carbonic acid, on the other hand, comes from wine production (because during fermentation the yeast converts the sugar of the grapes into alcohol and carbon dioxide ). It is either also (re)added to the finished still wine in the pressurised tank or is produced during a second fermentation of the base wine, during which the carbon dioxide formed cannot escape and therefore dissolves in the wine.
Wines with a carbonic acid pressure of 3 to 6 bar are called sparkling wines.