When Do You Add Sodium Metabisulfite to Wine?

Sodium metabisulfite is an important additive in winemaking, mainly used as a preservative and antioxidant. Here are the key stages when it is commonly added:

  • Before Fermentation:
    Add sodium metabisulfite to the must (crushed fruit/juice) to kill wild yeasts and bacteria. This helps ensure that only the chosen wine yeast strain will ferment the juice.
  • After Fermentation:
    After primary fermentation is complete and before aging, add more sodium metabisulfite to prevent oxidation and spoilage.
  • During Racking:
    Every time you transfer (rack) the wine off the sediment, it is common to add a small dose to maintain protection against spoilage organisms and oxidation.
  • Before Bottling:
    Just before bottling, add a final dose to ensure the wine remains stable and preserved in the bottle.

Note: The specific amount depends on the type of wine, pH, and existing sulfite levels. Always use appropriate testing equipment or calculators to avoid over- or under-dosing.