Acetic Acid
acetic acid. (uh-see'd:ik ae'-sid)
Formula: CH3COOH. A weak, monocarboxylic acid found in vinegar. It is the first member of the fatty acid series and also belongs to the larger group of carboxylic acids. This acid is a natural by-product of yeast metabolism and is formed via the Krebs cycle during aerobic respiration. In beermaking, it forms through oxidation of alcohols during the fermmentation process when the beer is exposed to air (oxygen), giving the beer a vinegar taste and smell.