steeping herbs and spices in them, and why vinegar can help remove greasy films from various surfaces Food Words: Vinegar, Acid, Acetic Though it doesn’t look or sound related, the word vinegar comes from the same root as both acid and acetic: the IndoEuropean ak-, meaning “sharp.” (The aigre i n vinaigre was originally the Latin acer.)Edge, acute, acrid, ester, andoxygen are related words, oxygen because its presence was once thought necessary to make an acid The Acetic Fermentation It takes three ingredients to make vinegar: an alcoholic liquid, oxygen, and bacteria of the genus Acetobacter or Gluconobacter, mainly A pasteurianus and A aceti These bacteria are among the few microbes that are able to use alcohol as an energy source Their metabolism of alcohol leaves behind two byproducts, acetic acid and water CH3CH2OH + O2 CH3COOH + H2O Alcohol + oxygen acetic acid + water Acetic acid bacteria require oxygen, and so live on the surface of the fermenting liquid, where with other microbes they form a film sometimes called the “mother.” Especially thick films are created by Acetobacter xylinum, which secretes a form of cellulose (Such mats are sometimes cultivated and eaten for themselves; see p 509.) Acetobacteria thrive in warm conditions, so vinegar fermentations are often carried out at relatively high temperatures, from 82 to 104ºF/28–40ºC The concentration of alcohol in the starting liquid affects the acetic fermentation and the stability of the resulting vinegar An alcohol concentration around 5% will produce a vinegar that is around 4% acetic acid, which is ... relatively high temperatures, from 82 to 104ºF/28–40ºC The concentration of alcohol in the starting liquid affects the acetic fermentation and the stability of the resulting vinegar An alcohol concentration around 5% will produce a... xylinum, which secretes a form of cellulose (Such mats are sometimes cultivated and eaten for themselves; see p 509.) Acetobacteria thrive in warm conditions, so vinegar fermentations are often carried out at... Acetic acid bacteria require oxygen, and so live on the surface of the fermenting liquid, where with other microbes they form a film sometimes called the “mother.” Especially thick films are created by Acetobacter