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
Wine from the United Kingdom Normans, with over 40 vineyards in England mentioned in the Domesday Book, although much of what was being produced was for making communion wine for the Eucharist. From the Middle Ages, the English market was the main customer of clarets from Bordeaux, France, helped by the Plantagenet kingdom, which included England and large provinces in France. In the 18th century, the Methuen Treaty of 1703 imposed high duties on French wine. This led to the English becoming a main consumer of sweet fortified wines like sherry, port wine, and Madeira wine from Spain and Portugal. Fortified wine became popular because