Small quantities of acetic acid (i.e. vinegar) are present in all wines, no matter how well made. However careless winemaking where at a little less than 0.1% the acid becomes noticeable the wine is termed acetic, over 0.1% and the wine is flawed.
Acetic acid is the acid that gives vinegar its characteristic taste. Small amounts of acetic acid, about 0.5 grams/liter, are normal in wine; amounts over 1.0 gram/liter give wine a vinegar-like character.
Wines contain several types of acid, but acetic is the bad one: it suggests vinegar and is sometimes referred to as volatile acidity. If present at more than minimal levels, it makes a wine unpleasant.
Wines, no matter how well made, contain quantities of acetic acidity that have a vinegary smell. If there is an excessive amount of acetic acidity, the wine will have a vinegary smell and be a flawed, acetic wine.
All wines contain acetic acid - (ie: vinegar). Normally the amount is insignificant and may even enhance flavor. At a little less than 0.10% content, the flavor becomes noticeable and the wine is termed acetic. Above 0.10% content is considered a strong fault. A related substance,ethyl acetate, contributes the smell associated with acetic acid content (see also ascence).