Definition: sulphur (in wine)

Today, the use of sulphur is strictly regulated at international level and varies according to the type of wine. Red wines for ageing contain the lowest doses, as their preservation is largely ensured by tannins. For simple red wines, rosés and dry whites, a higher quantity is permitted. Finally, sweet wines, because of the residual sugar they contain, are protected by the highest doses (up to 400 mg SO2/litre). The most progressive winemakers are content with values well below the legal maximum.

Sulphur is used primarily in the winery, when the grapes arrive, to eliminate harmful microbes and bacteria that could subsequently damage the wine. This risk is particularly high when the grapes are not completely healthy and show signs of rot. Sulphur is also used during racking to combat oxidation, as well as to seal barrels after they have been thoroughly cleaned with hot water. In the past, certain white wines had a bad reputation for causing headaches, mainly because they contained excessive amounts of sulphur. This is still sometimes the case with certain sweet and syrupy wines, which are more difficult to preserve. When used conscientiously, the taste of sulphur is not transferred to the wine. New hygiene standards in modern winemaking have made it possible to limit the doses and, in the absence of other solutions, the best wines are made with a minimum of SO2. A slight smell of sulphur (the smell of a burning match) is not uncommon when tasting a freshly bottled wine. Aeration by decanting is usually sufficient to eliminate it. If a wine smells like rotten eggs, this is evidence that the sulphur has been transformed into hydrogen sulphide, causing irreversible mercaptans. In several Anglo-Saxon countries, the words "contains sulphite" (contains sulphur) are mandatory on labels, particularly in the USA. Some producers, notably in Beaujolais and the Loire, manage to produce wines without any added SO2. These wines are more delicate and must be stored in cool cellars, but can be exceptional.

See also the entry "Sulphur - SO2".