Potassium Metabisulfite

Sulfites are one of the most important additives in winemaking, and most recently brewing. They are used to control spoilage during the harvest and the crush by inhibiting bacteria and wild yeast; they also act as a preservative during storage by continuing to inhibit spoilage organisms and scavenge oxygen. Sulfite solutions can also be used to sanitize winemaking equipment. For brewing, potassium metabisulfite eliminates chlorine in water.

Potassium metabisulfite is one of the most important winemaking compounds. It is an antioxidant and bactericide that releases sulfur dioxide into wine must. Use 1/4 teaspoon per five gallons to add 50 ppm. Or mix 1/4 pound in 1 quart of water to make a stock solution; 1 teaspoon of stock solution in one gallon of must yields 50 ppm sulfur dioxide.
Potassium Metabisulfite is an antibacterial agent identical in use to Sodium Metabisulfite but it does not add sodium to the wine.

For brewers, 175 mg will eliminate chlorine in 5 gallons of water.