What are sulfites used for in food?

These are natural preservatives, a stabilizer and an antioxidant. You find sulfites in many other foods. They have several names or carry a code between E220 and E228.

Are sulfites always naturally present in wine?

Yes and no. In most cases, the yeasts that transform sugar into alcohol during fermentation produce more or less sulfites in small quantities. This is why the law requires the term "wine without added sulfites" and not "wine without sulfites". That said, even if its presence is undetectable during analysis (less than 0.003 g/liter). There are a few very rare yeasts that never produce sulfites (we use them for our "sulfur-free" vintages).

In any case, to register the mention "wine without added sulfites", you must not have added any AND the quantity produced naturally by the yeasts must be less than 0.01 g/liter).

A key question: Why is sulfur used in wine?

Wine is a living product, which will continue to evolve and eventually become vinegar upon prolonged contact with oxygen. Adding a little sulfite is the solution imagined by winemakers, to considerably increase its lifespan as wine.

Who was the first to use sulfites to preserve wine?

A priori, it was the Romans, but without formal proof, who burned sulfur to preserve their amphorae.

An official document in the form of a German royal decree from 1487 explicitly authorizes its use in wine to increase its conservation.

In the 18th century, sulphur wicks were regularly used to inert barrels.

We can logically think that it would be enough to deprive the wine of contact with oxygen to do without sulfites?

Yes, but here's the thing, wine already contains dissolved oxygen, and it needs it anyway to evolve and improve over time. As is often the case in the world of wine, it's about finding the right balance between too much and not enough.

But then, wines without sulfur do not keep?

Keeping wines without sulfites (especially after opening) is indeed much more difficult. There are a few winemaking techniques that can greatly limit the risks. In summary, the idea is to limit the oxygen supply as much as possible and to inert the wine with heavier gases such as carbon dioxide, which is naturally very present during winemaking.

What exactly is the oxidation of a wine?

It is the reaction of wine with oxygen: it can alter the color and aromas, or even dry out the wine.

Oxygen, but not too much: A wine that lacks oxygen is said to be "closed": its aromas are "hidden" behind other unpleasant aromas (animal, stable, etc.). It is generally enough to aerate it in its glass, or to decant it so that it "opens up". A wine that has too much oxygen is "stale", its aromas have been altered and they will never come back...

A winemaker will always prefer his wines in vats to lack oxygen, rather than the opposite. This slight reduction will naturally protect the wine against its main enemy.

Are all grape varieties equal when it comes to oxidation?

Well no: white grape varieties are more fragile (even daylight oxidizes the juices), which is why the harvest is often carried out at night.

So-called "reductive" grape varieties, such as Syrah, need more oxygen than "oxidative" grape varieties, such as Grenache. Reductive grape varieties are much less sensitive to oxygen, which is why our sulfite-free wines have more Syrah than Grenache in their blends.

Is it easier to make wines without sulfur in the south or in the north?

In fact, no matter the region, the most important thing is that the harvest is perfectly healthy. In fact, sulfites also serve to sanitize the harvest when it arrives in the cellar. It is true that regions where it rains less and where there is a lot of wind, such as in the south of the Rhone Valley, are ideal for producing these delicate wines.

Note that red wines that contain tannins are better equipped than white or rosé wines to do without sulfites. Indeed, tannins strengthen wines, particularly against oxidation.

On the other hand, wines that still contain sugar, such as sweet or liqueur wines, are little "bombs": Since fermentation is not completely finished, it can start again at any time. It can therefore produce carbon dioxide which will increase the pressure inside the bottle and "push" the cork out of the bottle. Since wine containers are generally stored lying down, this is a sure disaster.

To avoid this problem, only sulfites prevent the resumption of fermentation by preventing yeasts and lactic bacteria from surviving and therefore continuing their purpose. A sweet wine without sulfites therefore seems impossible unless it is fortified with alcohol (which also prevents bacterial and microbial life).