Which acid is found in vinegar?

The acid found in vinegar is acetic acid, also called ethanoic acid.

Vinegar is not pure acetic acid; it is mainly water containing diluted acetic acid and small amounts of flavor compounds. Typical table vinegar contains about 4% to 8% acetic acid, although concentrations vary by product and use. The acid gives vinegar its characteristic sour taste and sharp smell.

Most vinegar is produced through two stages of fermentation. Yeast first converts sugars into ethanol. Acetic-acid bacteria then use oxygen to convert the ethanol into acetic acid. This process explains why wine, beer, cider, and other alcoholic liquids can turn sour when exposed to air.

Acetic acid is a weak acid in ordinary vinegar, unlike hydrochloric acid, which is much stronger and is not vinegar’s characteristic ingredient. Citric acid is associated with citrus fruits, while lactic acid is produced in processes such as sour-milk fermentation. Acetic acid is also used in pickling, food preservation, and industrial chemical manufacturing.