Sulphites are compounds containing sulphur dioxide (SO₂) and related sulphur species that occur naturally in wine and may also be added during winemaking. They are used as preservatives because they help protect wine from oxidation and unwanted microbial activity. Sulphites are present in many foods and beverages, including dried fruit, beer, cider and some processed products.
Sulphur dioxide has antioxidant and antimicrobial properties. Winemakers may use it at different stages, including grape processing, fermentation, maturation and bottling, to help preserve freshness and stability. Yeast can also produce small amounts of sulphur dioxide naturally during fermentation, so even wines with no added sulphites may contain some naturally occurring sulphites.
In Canada and the United States, wines containing sulphites above the applicable threshold must carry a sulphite declaration. Some people, particularly certain individuals with asthma, can be sensitive to sulphites and may experience reactions. Sulphite sensitivity is different from an allergy to grapes or alcohol, and the actual prevalence is relatively low.
Some low-intervention producers add little or no sulphur dioxide, while others use controlled additions to protect the wine. “No added sulphites” does not necessarily mean sulphite-free because fermentation can produce naturally occurring sulphites.
Example: a wine label may state “Contains Sulphites” because the total sulphite level exceeds the applicable labelling threshold.
Chef’s note: sulphites are not unique to wine and do not automatically indicate poor quality. Follow allergen and ingredient communication requirements, and do not make unsupported claims that a wine is sulphite-free.
This term is one of hundreds covered in depth across OCS courses, learning paths, and 1-on-1 coaching with Chef Eric.
