Potassium metabisulfite is added to wine to inhibit bacteria and yeast growth, as well as slow down oxidation. It may leave an unpleasant aftertaste in wine if the dose is too high. This chemical is also used in a water solution as an antiseptic rinse to sanitize equipment For wine, use 1/8 teaspoon (1 gram) of powder per gallon of wine. A little bit goes a long way, so be careful! For sanitizing solution, dissolve 1 to 2 oz. (2 to 4 tablespoons) Potassium Metabisulfite powder in one gallon of water.