Acids in wine responsible for the sour taste of vinegar. During fermentation, activity by yeast cells naturally produces a small amount of acetic acid. If the wine is exposed to oxygen, "Acetobacter" bacteria will convert the ethanol into acetic acid. This process is known as the “acetification” of wine and is the primary process behind wine degradation into vinegar. An excessive amount of acetic acid is also considered a wine fault. A taster's sensitivity to acetic acid will vary, but most people can detect excessive amounts at around 600 mg/l. Ascorbic acid, also known as vitamin C, is found in young wine grapes
Sparkling wine comes from its carbon dioxide content and may be the result of natural fermentation, either in a bottle, as with the traditional method, in a large tank designed to withstand the pressures involved (as in the Charmat process), or as a result of simple carbon dioxide injection in some cheaper sparkling wines. In EU countries, the word "champagne" is reserved by law only for sparkling wine from the Champagne region of France. The French terms "Mousseux" and "Crémant" refer to sparkling wine not made in the Champagne region, such as Blanquette de Limoux produced in Southern France. Sparkling wines are