The rewards and frustrations of home winemaking

SO2; Kmeta; sulfite; Metabisuphite; potassium metabisulphite

Sulfites areย  used to control spoilage during the harvest and the crush by inhibiting bacteria and wild yeast, as well as being a preservative during storage by continuing to inhibit spoilage organisms and block oxidation. Sulfite solutions can also be used to sanitize winemaking equipment.ย  Either potassium metabisulfite (AKA Kmeta) or sodium metabisulfite could be used, but use of potassium metabisulfite will not add sodium to the wine.ย  Addition of 1/4 teaspoon per five gallons yields approximately 50 ppm sulfur dioxide (SO2).

http://waterhouse.ucdavis.edu/winecomp/so2.htm