Sulfites are produced naturally during fermentation, but are also added to stop the fermentation process. In wine, they act as preservatives to prevent deterioration due to both their antioxidant capacity and their antimicrobial action. The concept of total sulfites referers to any sulfite present either in the form of anhydrous sulphur (SO2), bisulfite ion (HSO3) or sulfurous acid (H2SO3), but also other forms linked to other compounds such as sugars or polyphenols. It is necessary to control the maximum concentration of sulfite present since at high concentrations it can be toxic.
