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
Acids in wine acidity will become more noticeable to wine tasters if added at this point. The acidity in wine is an important component in the quality and taste of the wine. It adds a sharpness to the flavors and is detected most readily by a prickling sensation on the sides of the tongue and a mouth-watering aftertaste. Of particular importance is the balance of acidity versus the sweetness of the wine (the leftover residual sugar) and the more bitter components of the wine (most notably tannins but also includes other phenolics). A wine with too much acidity will taste excessively sour and