Does Sodium Metabisulfite Kill Yeast?

Sodium metabisulfite is a chemical compound commonly used as a preservative and antioxidant in winemaking, brewing, and food processing. It releases sulfur dioxide (SO₂) when dissolved in water.

Effect on Yeast

• Inhibits Yeast Activity: At certain concentrations, sodium metabisulfite can inhibit and slow down yeast fermentation by interfering with yeast cell metabolism.
• Kills Yeast at High Doses: In higher dosages, sodium metabisulfite can kill yeast cells by disrupting their cellular processes and reducing the population significantly.
• Preservation: It is often added to must or juice to kill wild yeasts and bacteria before pitching a desired yeast strain for fermentation.

In summary: Sodium metabisulfite can kill yeast at sufficient concentrations, but its primary use is to inhibit and control wild microbes rather than to sterilize completely. The dosage needed to kill yeast is higher than the amount typically used for preservation or antioxidant effects.