One of the six taste sensations (besides bitter, fatty, salty, sweet, umami), which is mainly perceived in the middle part of the tongue. However, the acid sensation is relatively strongly dependent on the wine temperature. With warmth, the impression of sharpness is further enhanced by the interaction of alcohol and acidity. A dry white wine with a total acidity of 7 g/l appears very acidic at a high temperature of 18 °Celsius, but pleasantly fresh at an optimal drinking temperature of 10 to a maximum of 12 °Celsius.
The different acids in wine cause different sensations. Lactic acid has only a weakly acidic taste, acetic acid a sharp one and malic acid clearly the most "acidic" taste. A particularly high malic acid content can contribute to an unpleasant impression. Succinic acid, on the other hand, tastes most intense and also slightly bitter and salty.
In the context of a wine address, "sour" has a negative connotation - in contrast to the positive connotation of "acidic". Such a wine has a too high and unharmonious acidity, and possibly also too many tannins. The cause can be unripe grapes, a rainy harvest or various wine faults. In context negatively occupied terms are aggressive, biting, angular, sharp and strict. A rich, balanced amount of acidity is an important component of a wine. In the context of positive connotations, terms are finely acidic, lively, pithy, annoying, racy, crisp, tart, acid accentuated, playful (acid play), tangy and steely.
The opposite of sour is sweet in taste. This does not apply, however, from a chemical point of view; here the opposite of sour is alkaline. An acidic sense of taste does not mean that something is chemically acid (i.e. not alkaline). A lemon, for example, tastes sour, but is alkaline. See also under wine enjoyment.