The most important acid (also 2,3-dihydroxy succinic acid or 2,3-dihydroxybutanedioic acid) in wine with a proportion of 0,5 to 4 g/l, which is one of the non-volatile acids. Before the discovery of tartaric acid proper, its salt potassium hydrogen tartrate - tartrate - was considered a solid acid, as it is easily precipitated in wine due to its poor water solubility. In the past, it was therefore easier for chemists to identify it than tartaric acid, which is highly soluble. In 1769, the German-Swedish chemist Karl Wilhelm Scheele (1742-1786) separated this from tartar and therefore named it tartaric acid. After its continuous build-up in the grapes during the ripening period, the proportion no longer decreases in contrast to malic acid. In the case of persistent cold, tartar can already be precipitated in the grape.
Tartaric acid is by far the most acidic tasting acid in wine. It is approved within the EU as food additive E 334. It is also used to acidify low-acid wines in order to increase the acidity, in accordance with the specific national wine legislation. Metatartaric acid is esterified tartaric acid, which is added shortly before bottling to prevent the precipitation of tartaric acid or to stabilise it. The total content of total acidity in wine is given by the collective term tartaric acid, although other acids are also included. A derivative of tartaric acid is grape acid. See the wine ingredients under total extract.