Preservative which is added to nearly all wines to protect them from oxidation and microbial infection.

What is sulfur dioxide?

Sulfur dioxide is a compound that contains sulfur and oxygen. It can be produced in its simplest form by burning elemental sulphur, hence the confusing usage of the term ‘sulfur’, when actually SO2 is meant. SO2 is identified in foodstuffs as E220. Two other forms are permitted in wine: E224, potassium metabisulfite; and E228, potassium bisulfite.

Collectively these are referred to as ‘sulfites’, hence the term used on labels.

Toxicity: SO2 is toxic in large quantities; however, the amounts used in wine production are minute. SO2 intolerance is very rare, and most likely to be found in individuals with a pre-existing disorder such as asthma.

EU limits for SO2 usage

Dry red wine – 150mg/l

Dry white and rosé wine – 200mg/l

Red wine with 5g/l sugar or more – 200mg/l

White wine with 5g/l sugar or more – 250mg/l

Spätlese – 300mg/l

Auslese – 350mg/l

Trockenbeerenauslese, Beerenauslese, Sauternes – 400mg/l

Since 2012, permitted limits in organically certified wines are 30mg/l less in each category