What are sulphites used for?
Sulphites are added to wine as sodium metabisulphite or potassium metabisulphite. Both chemicals act as a source of free sulphite ions in the juice. The sulphite does two useful things. 1) It prevents contamination of the juice by wild yeasts and other spoilage organisms. 2) It acts as an antioxidant, by sacrificially oxidising itself, forming sulphates in the process. Without sulphites, white wines tend to go brown and flat, like a sliced apple. If you are making table wine from purchased juices, for early drinking, then you do not need to use sulphites. But if you are using fruit or vegetables, or if you intend maturing the wine, careful use of sulphites is recommended.
