Question: when do you add citric acid to wine

title: Acids in wine
text: Acetic acid is a two - carbon organic acid produced in wine during or after the fermentation period . It is the most volatile of the primary acids associated with wine and is 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 .