Sulfites occur naturally in all wines to some extent. Sulfites are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of the winemaking. Sulfur dioxide (SO2) protects wine not only from oxidation, but also from bacteria.
Sulphur dioxide has been used in winemaking for thousands of years, ever since the ancient Romans discovered that it would keep their wine from turning into vinegar. To this day, winemakers use sulphur dioxide to preserve the flavor and freshness of wines.
In the United States, wines bottled after mid-1987 must have a label stating that they contain sulfites if they contain more than 10 parts per million (ppm).
In the European Union an equivalent regulation came into force in November 2005. In 2012, a new regulation for organic wines came into force. In the United Kingdom, similar laws apply. Bottles of wine that contain over 10 mg/L (ppm) of sulfites are required to bear “contains sulphites” on the label. This does not differ if sulfites are naturally occurring or added in the winemaking process.
Scientists have found no link between sulfites in wine and headaches. In fact, for people who have this allergy, the typical response is not a headache but hives and difficulty breathing. What’s more, white wines generally have more added sulfites than reds.
Health effects about sulfite
Allergic reactions to sulfites appear to be very rare in the general population, but more common in hyperallergic individuals.
Sulfites are counted among the top nine food allergens, but a reaction to sulfite is not a true allergy. Some people have positive skin allergy tests to sulfites indicating true (IgE-mediated) allergy. Chronic skin conditions in the hands, perineum, and face have been reported in individuals that regularly use cosmetics or medications containing sulfites. Occupational exposure to sulfites has been reported to cause persistent skin symptoms.
It may cause breathing difficulty within minutes after eating a food containing it. Asthmatics and possibly people with salicylate sensitivity (or aspirin sensitivity) are at an elevated risk for reaction to sulfites. Anaphylaxis and life-threatening reactions are rare.Other potential symptoms include sneezing, swelling of the throat, hives, and migraine.
A 2017 study has shown negative impacts of sulfites on bacteria found in the human microbiome
Organic wines are not necessarily sulfite-free, but generally have lower amounts and regulations stipulate lower maximum sulfite contents for these wines. In general, white wines contain more sulfites than red wines and sweeter wines contain more sulfites than drier ones.
Sulfites are often used as preservatives in dried fruits, preserved radish and dried potato products.
Most bars no longer contain sulfites, although some alcoholic ciders contain them. Although shrimps are sometimes treated with sulfites on fishing vessels, the chemical may not appear on the label.
In 1986, the Food And Drug Administration in the United States banned the addition of sulfites to all fresh fruit and vegetables that are eaten raw.