Carbonic acid first became known in mineral waters because of its acidic taste. It is the reaction product of its anhydride carbon dioxide with water. Despite its carbon content, it is counted among the inorganic acids. The gas carbon dioxide is easily soluble in water and reacts to a small extent (about 0.2%) to form carbonic acid. This is therefore present in every wine in the smallest quantity and in sparkling wine in a somewhat larger quantity. By far the largest part, however, with over 99%, is the carbon dioxide dissolved in the wine. The term carbonic acid is often used colloquially for carbon dioxide, even in technical literature. For example, in the case of sparkling wine, one speaks of carbonic acid pressure and not carbon dioxide pressure. The bubbles are considered an important indication of the quality of a sparkling wine, the criterion being the sparkling quality. Carbon dioxide dissolved in water (which does not yet produce carbonic acid) is usually grouped with the actual carbonic acid as "free carbonic acid". The esters and salts of carbonic acid are called carbonates. These include dimethyldicarbonate and potassium bicarbonate, which are used in winemaking.
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Diplom-Sommelier, Weinakademiker und Weinberater, Volders (Österreich)