What are sulphites in wine?

Sulphites are sulphur dioxide and its salts. Winemakers use them to slow oxidation and to hold back unwanted yeasts and bacteria.

In the cellar, sulphur dioxide is added at harvest, after fermentation and just before bottling. It slows enzymatic and chemical oxidation and keeps unwanted yeasts, lactic acid bacteria and acetic acid bacteria in check. Part of it binds to substances in the wine; what remains is called free sulphur dioxide. Free plus bound makes up the total the law looks at.

Yes. During alcoholic fermentation, yeasts produce sulfur dioxide themselves, usually less than 10 milligrams per liter, up to 30 milligrams per liter with some yeast strains.

Yeasts convert sulfate in the must and release sulfur dioxide in the process. How much that is depends on the yeast strain and the conditions during fermentation. A wine to which the maker adds nothing therefore almost always still contains a small amount.

For ordinary still wine the limit is 150 milligrams of total sulfur dioxide per liter for red and 200 milligrams per liter for white and rosé.

The limits are set out in Annex I part B of Delegated Regulation (EU) 2019/934. If the wine contains 5 grams of residual sugar per litre or more, the limit rises to 200 milligrams per litre for red and 250 for white and rosé. For a series of sweet wines with a protected designation, 300 or even 350 milligrams per litre applies.

The statement is mandatory from more than 10 milligrams of total sulphur dioxide per litre. Dutch labels then say bevat sulfieten or bevat zwaveldioxide.

The obligation comes from the European allergen rules and is elaborated for wine in delegated regulation (EU) 2019/33. Article 41 provides that the terms from Annex I part A must be used. The exact content need not appear on the bottle; only the statement itself is mandatory.

Organic wine may contain less sulphite: 100 milligrams per litre for red and 150 milligrams per litre for white and rosé, with residual sugar below 2 grams per litre.

Those limits are 50 milligrams per liter below the general limits. For all other organic wines the general limit value reduced by 30 milligrams per liter applies. The rules were introduced by Regulation (EU) No 203/2012 and now fall under Regulation (EU) 2018/848.

Wine without added sulphites exists; completely sulphite-free wine almost does not. Yeasts almost always produce a small amount of sulphur dioxide during fermentation.

On labels you therefore read no added sulphites and not sulphite-free. If the total stays below 10 milligrams per litre, nothing has to be declared.