Acetic acid is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H or C2H4O2). When undiluted, it is sometimes called glacial acetic acid. Vinegar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. It is what gives the sourdough bread its distinctive "sourness". The longer the dough ferments under either warm or cold temperature, the more prominently flavored the bread will taste. Acetic acid is found in differents concentrations in many fermented goods, such as picked products, kombucha, wine, and the most known one, with a significant concentration, table vinegar.