Sodium Metabisulphite is a highly pure substance (over 99%) used to prevent moulds, bacteria, and microbial spoilage. It is also an effective agent in fighting off oxygenation. The chemical formula for Sodium Metabisulfite is Na2S2O5, also known as disodium metabisulfite. It has a variety of uses, including as a bleach, preservative, anti-browning agent, flour treatment agent, and antioxidant. 
 
1. Sanitization and Cleaning:
To sanitize equipment: Prepare a solution of sodium metabisulfite by dissolving 1 to 2 ounces (28 to 56 grams) of sodium metabisulfite in 1 gallon (3.8 liters) of water. Use this solution to sanitize equipment before and after use.
 
2. Must (Crushed Grapes or Fruit Juice) Treatment:
To prevent oxidation and microbial growth: Add 1/4 to 1/2 teaspoon (approximately 1.4 to 2.8 grams) of sodium metabisulfite per 5 gallons (19 liters) of must before fermentation. This helps protect the must from spoilage and oxidative reactions.
 
3. Aging and Bottling:
To protect wine during aging: Add 1/8 to 1/4 teaspoon (approximately 0.7 to 1.4 grams) of sodium metabisulfite per 5 gallons (19 liters) of wine before transferring it for aging. This helps maintain wine quality and prevents oxidation.