By Malvina Demaj Last Updated: Mar 17, 2026

Sulfites

(sul-faits)
DEFINITION

Sulfites

Sulfites (sulfur dioxide or SO₂) are chemical compounds naturally produced by yeast during wine fermentation. They act as preservatives, also commonly added by winemakers to prevent bacterial growth, spoilage and oxidation. All wines contain sulfites, whether natural or added, ranging from 50 to 100 mg/L. In the US, wines with more than 10mg/L of sulfites must be labelled “Contains Sulfites”.

Did you know? Dried fruits, canned veggies and potato chips often contain higher sulfite levels than wine (up to 10x more). The theory that sulfites are responsible for wine headaches has been disproved.

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