Potassium Metabisulfite is most commonly used while making wine. This product helps to remove other forces which block typically block the yeast, so the yeast can do its job in the fermentation process, while destroying wild bacteria and yeast, to make way for desired yeasts and bacterias. The pH levels and the state of your grapes hugely affect the amounts of potassium metabisulfite needed. When used correctly, sulfites reduce the browning capabilities of white wines and can even improve flavor! Old Metabisulfites can be used for sanitization.