Wine Analysis

Sulphur dioxide's effect on microorganisms

• Sulphur dioxide (SO₂) can be effective as a anti microbial agent.
  
  
• The molecular form of SO₂ (sulphur dioxide) is the most effective form and it has been calculated that 0.8 ppm molecular SO₂ is required to inhibit microbial growth and activity (see table or equation for calculations)
  
  
• Bacteria, in particular lactic acid bacteria (LAB), are very sensitive to SO₂
  
  
• Sulphur dioxide also acts as a yeast inhibitor, but to a lesser degree.
  
  
• Yeasts can detoxify SO₂ by producing acetaldehyde during fermentation which it will bond to and inactivate the SO₂ (sulphur dioxide).
  
  
• Sensitivity to SO₂varies amongst yeast strains and this variability can be used to select in favour of the desired yeast strain.