Potassium Metabisulfite is a common additive used to preserve and stabilize wines, ciders, and occasionally beers. When added to wine or must, it forms sulfur dioxide gas (SO₂). This prevents most wild microorganisms from growing and acts as a potent antioxidant, protecting both the color and delicate flavors of wine. Potassium Metabisulfite solutions are also used as sanitizing rinses for winemaking equipment.

Recommended usage: Dosage varies when used to kill wild bacteria in must, halt fermentation, or preserve finished wines against oxidation. The addition of ¼ teaspoon of potassium metabisulfite to 5 gallons contributes approximately 50 ppm of free SO₂.

To make a sanitizing rinse for equipment, dissolve 8 teaspoons of potassium metabisulfite into 1 gallon of water. High concentrations of sulfur dioxide gas are irritating and toxic, so use in a well ventilated area. After applying the solution to your equipment, the items must be rinsed with clean, cold water.