In contrast to non-volatile acids, volatile acids evaporate during distillation or volatilise over time (turn into a gas). However, the borderline between volatile and non-volatile cannot be drawn exactly, as there are also "medium volatile acids". The volatile acids contained in wine with their chemical compounds are for the most part acetic acid (0.15 to 0.5 g/l in healthy wine), which is feared when the limit is exceeded and which causes the wine defect acetic souring (also called "volatile acid"). Other volatile acids are formic acid, succinic acid (rather already medium volatile), butyric acid, propionic acid (propanoic acid) and valeric acid (pentanoic acid). Carbonic acid, which is also volatile, is not included in this group. The total quantity is determined by means of steam distillation and given as the collective term acetic acid in grams per litre. The non-volatile and volatile acids make up the total acidity. See also volatile. A list of all wine constituents is included under total extract.
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Roman Horvath MW
Domäne Wachau (Wachau)