Potassium Metabisulfite is a white powder with a sulphurous odour. It's used in winemaking as an antioxidant, sterilant, and preservative.  It also serves as a preservative, keeping food's colour and fighting bacteria. 
 
1. Sanitizing Equipment:
Dissolve 1 tablespoon (approximately 15 grams) of potassium metabisulfite in 1 gallon (3.8 liters) of water.
Use this solution to sanitize winemaking equipment, including fermentation vessels, bottles, and utensils. Rinse thoroughly with clean water after sanitizing.
 
2. Wine Preservation:
To protect wine from oxidation and microbial spoilage, you can add potassium metabisulfite during different stages of winemaking.
For pre-fermentation, a common dosage is 1/4 teaspoon (approximately 1.25 grams) of potassium metabisulfite per 5 gallons (19 liters) of must (crushed grapes or fruit juice).
For post-fermentation, a typical dosage is 1/4 teaspoon (approximately 1.25 grams) per 5 gallons (19 liters) of wine.
Be sure to accurately measure the dosage and dissolve it in a small amount of wine or water before adding it to the larger volume to ensure even distribution.
 
3. Sterilization of Bottles:
To sterilize wine bottles before filling, you can prepare a potassium metabisulfite solution by dissolving 2-3 tablespoons (approximately 30-45 grams) of potassium metabisulfite in 1 gallon (3.8 liters) of water.
Immerse the bottles in this solution for a few minutes, rinse them with clean water, and allow them to air dry before filling with wine.