Acetic acid, or ethanoic acid, (CH3COOH) is a carboxylic acid, which is the main compound of vinegar, other than water. It tastes and smells sour; it has no color. Its melting point is 16.5 °C(61.6 °F) and boiling point is 118.1 °C(244.5 °F). It has a pH of 2.4.
Acetic acid is commonly used as a food additive. It has the E numbers E 260 (acetic acid). Potassium acetate (E 261), sodium acetate (E 262), and calcium acetate (E 2639 are salts of acetic acid; they are commonly used in preserving food, usually vegetables. In sourdough, ethanol fermentation is used.