It serves two purposes. When active fermentation has ceased and the wine is racked for the final time after clearing potassium sorbate will render any surviving yeast incapable of multiplying. Yeast living at that moment can continue fermenting any residual sugar into CO2 and alcohol but when they die no new yeast will be present to cause future fermentation. When a wine is sweetened before bottling potassium sorbate is used to prevent refermentation when used in conjunction with potassium metabisulfite. It is primarily used with sweet wines sparkling wines and some hard ciders but may be added to table wines which exhibit difficulty in maintaining clarity after fining. When active fermentation has ceased and the wine racked the final time after clearing 1/2 tsp. added to 1 gallon of wine. When a wine is sweetened before bottling potassium sorbate is used to prevent refermentation. It should always be used in conjunction with potassium metabisulfite (1/4 teaspoon per 5 gallons of wine or 1 crushed and dissolved Campden tablet per gallon) and the wine will not be stabilized without it.