Although lots of things are added to conventional wine, it seems to be sulfites that garner the most attention in the world of wine. Sulfites are compounds that occur naturally in some foods and are also used as a preservative. When added to wine, they stabilise and preserve it, preventing a wine from becoming oxidised.

Sulfites occur naturally in wine via the fermentation process but typically in scant amounts. The majority of sulfites in wine is added by the winemaker when the wine is being bottled. Sulfites may also be labelled sulphur dioxide, which is why you may hear these terms used interchangeably.

The general consensus for a natural wine is that it should have little to no sulfites added at bottling. The substance is not only mildly allergenic for some, but it can strip wine of its characteristics.

However, there are big risks in avoiding added sulphur—wines can re-ferment in the bottle, for instance. Pulling off a beautiful, expressive wine with zero sulphur takes serious skill. Importer Tess Bryant of Tess Bryant Selections believes that “once sulfites are added to wine, aromatics and flavour are altered and the wine is fundamentally changed. For me, it is not so much the taste of sulphur and the presence of it: it masks some of the true identity of the wine.”

There is a seemingly near-constant debate about how many sulphites can be added to a wine and have it still be deemed natural, and the debate doesn’t appear to be coming to a conclusive end anytime soon.

In most countries, any bottle of wine that contains more than 10 parts per million (ppm) is required to have a declaration on the label. Below is a breakdown on what amount of sulfites you can expect in various approaches to winemaking:

Conventional Wine

Permitted to contain up to 300 ppm of sulfites; however, totals are never listed on a wine bottle. Because of this, I avoid conventional wines in general, knowing that some can have such excessive amounts.

Certified Organic Wine

In the United States, Certified Organic Wine may have no added sulfites (but naturally occurring sulfites are fine).

Organically Grown Grapes

In the United States, wine made with organically grown grapes may have up to 100 ppm of sulfites. You’ll see “Made with Organically Grown Grapes” on these wine labels. While there is no current regulation on this, 100 ppm of sulfites far exceeds what the wine community deems natural.

Natural Wine

Most agree that zero added sulfites is ideal, with a lot of natural winemakers having totals around 25 ppm. Bryant feels that “Natural wine actually does have a definition: wine from organic (or better) grapes produced with no additions or subtractions.”