The Acetic Acid is a simple two-carbon fatty acid and one of the more common organic chemicals encountered in foods, it is also the most prevalent of the volatile acids. This is a naturally occurring organic acid that makes up the majority of a wine’s volatile acidity. Combined with ethanol, it produces ethyl acetate (nail polisher smell at high concentration) that gives the vinegar smell to a wine (acescence), also called ‘Piqure Acetique‘ in French.

The Acetic Acid is also one of the main flavour constituent responsible for the sour taste of vinegar.


Acetification (the process of transformation into vinegar) of a wine begins when it is exposed to oxygen, which allows acetobacter bacteria to transform the wine’s alcohol into acetic acid. Such a wine may be described as acetic.

Consequences of Acetification on a wine

The Acetic Acid is also directly produced during primary fermentation and most wines have detectable acetic acid levels which are the resylt of normal yeast acivity. Furthermore, it is the main contributor to the measure of volatile acidity in wine. The acetic acid perception threshold inside a wine is considered to be around 600 mg/liter.

Causes of formation of wine’s acescence

The 3 main causes of wine’s acescence are:

  • at the very beginning of fermentation, the yeasts present on the grapes can produce acetic acid or ethyl acetate
  • during alcoholic fermentation, lactic bacteria can produce acetic acid from sugars, this is called “lactic sting” (‘piqure lactique’ in French)
  • during wine ageing, acetic bacteria can transform, in contact with air, ethanol into acetic acid, this is what is called “acetic bite” (‘piqure acetique’ in French)

Acetic acid bacteria

What is generally called Acetic Acid is in fact a family of genera which includes Acetobacter and Gluconobacter.

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