Potassium Metabisulphite (PMS) is used for sterilizing & stabilizing wines, or ciders. It is an antioxidant and bactericide that releases sulfur dioxide into wine must.
Use 1/4 teaspoon per five litres to add 50 ppm (for stabilizing)
Use 12g - 20g per 25L of must to kill bacteria on the grapes, or wine must 24hours PRIOR to adding yeast.
Common practices include:
Crushing/Destemming:A common practice is to add 50 ppm of SO2 at this stage to suppress unwanted microorganisms.
After Fermentation:If you plan on performing Malolactic Fermentation, add 0-10 ppm SO2. If not, move on to the next step.
After Malolactic Fermentation and Before Aging:Add 50 ppm SO2. This is a significant addition before aging.
Racking:Add about 25 ppm SO2 each time the wine is racked.
Bottling:Add about 35-40 ppm SO2 at bottling to help preserve the wine.
