Vinegar

Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to ethanol using yeast, and ethanol to acetic acid by acetic acid bacteria.

With a history of more than 5,000 years, as its first traces are founded in Egypt and Mesopotamia before 3000 BC, vinegar is probably the first flavour that man used to add to his food to make it more tasty.