Everything you need to know about sulphites

dans le vin

Naturally present in wine, sulphites are different forms of sulphur, a mineral with antiseptic and antioxidant properties.

For ensuring that your favourite bottles don’t turn to vinegar, sulphites are invaluable to winemakers. Naturally present in wine, these chemical compounds are sulphur in a variety of forms (gaseous, liquid or powdered), sulphur being a mineral with antiseptic and antioxidant properties. These oenological products are used at various stages of the winemaking process as preservatives, to protect wine from oxygen and the development of undesirable micro-organisms. And now, read on to find out more about sulphites in wine!

What are sulphites in wine?

Let’s start with a definition of sulphites in wine. They are various forms of sulphur, a mineral element naturally present in wine. Why is this? Quite simply because, in any fermentation, yeast produces sulphites! These play a crucial role, thanks to their antiseptic and antioxidant properties.

What is the role of sulphites in wine?

Firstly, sulphur in wine helps to prevent oxidation. In other words, it protects wine from the harmful effects of oxygen, which can alter its colour, aromas and taste.

What’s more, sulphites are essential ingredients in a wine because of their ability to control micro-organism populations: they act as a wine preservative by inhibiting the growth of these bacteria and yeasts at different stages in the winemaking process. Result: sulphites prevent the formation of any unpleasant flavours.

This antioxidant and preservative role can also be fulfilled by other inputs into the wine: potassium sorbate (E202), L-ascorbic acid (E300), lysozyme (E1105) or dimethyl dicarbonate, also known as DMDC (E242).

How do these preservatives work in wine?

In practical terms, sulphites prevent oxidation reactions by binding to the oxygen molecules in a wine. What’s more, they prevent the growth and reproduction of unwanted bacteria and yeasts. That’s why the word “sulphites” may appear on the label of your wine!

How are sulphites added to wine?

Sulphur comes in three forms, all of which can be used in a wine:

Gaseous: sulphur dioxide, a chemical compound with the formula SO2 (E220);
Liquid: potassium bisulphite (E228);
Powder: potassium metabisulphite (E224).

These three forms are used separately as additives in wine at different stages of vinification. Sulphites can be added to the grapes or must before fermentation, after fermentation or during bottling.

Is the level of sulphur the same in different types of wine: white, red, sparkling, etc.?

The dosage of sulphites in a wine is meticulously controlled, and tends to depend on its colour. In fact, thanks to their longer maceration in contact with the skin and pips, red wines benefit more from the antioxidants naturally present in their grapes. As a result, fewer sulphites are added to red wines than to rosé, white or sparkling wines (such as champagnes or crémants).

Do bottles of organic wine contain sulphites?

Fermentation naturally produces sulphites: in organic wines, sulphites can therefore also be present, as in most biodynamic and natural wines. However, the sulphur content of these wines can vary.

Where else are sulphites used, apart from in oenology?

As well as wine, other popular alcoholic drinks use sulphites: beers are a good example. Sulphites are also widely used as food additives, in dried fruit, jams, fruit juices, certain sauces and crisps.

By now you’ve got it: to guarantee epicureans an optimal tasting experience, it is often useful to add sulphites to wine (and always with precision and care, as the science of good wine requires !).