The colourless liquid (also known as acetic acid, ethanoic acid, glacial acetic acid, ethanoic acid) is one of the most common organic compounds in food. It was discovered earliest of all acids in the form of vinegar and was already well known to the Egyptians, Babylonians and Chinese in ancient times. Undiluted acetic acid is highly corrosive to the skin. It is relatively easy to recognise by its characteristic vinegar smell, which is particularly noticeable when diluted. The flavour is still distinctly acidic even after extensive dilution.
Content in wine
Acetic acid is the most common volatile acid in wine. Healthy wines have a content of 0.15 to 0.5 g/l, while particularly sensitive tasters will criticise a wine from 0.6 to 0.7 g/l. Above this amount, this indicates spoilage or acetic souring, which is considered a serious wine defect.
Origin
It is formed during fermentation by acetobacter (acetic acid bacteria) through the oxidation of alcohol via the intermediate product acetaldehyde. Colloquially, this is also referred to as acetic acid fermentation. However, this is not fermentation, but an oxidative metabolic process or fermentation. Acetic acid bacteria can also enter the grape must with grapes that are already infected with it.
The reaction of acetic acid with alcohol during fermentation also produces acetic acid ethyl ester, which in excessive quantities can lead to the wine defect Uhuton (also known as acetic ester clay, adhesive clay; with a typical acetone odour). Another aromatic compound is acetic acid isoamyl es ter. The total amount of all volatile acids contained in wine is given as acetic acid. Different maximum limits apply depending on the type of wine; these are
Further information
There are also other substances in wine for which limit values are defined; see ADI (acceptable daily intake). Lists of all wine ingredients can be found under flavourings and total extract.
