Binding forms of SO₂: free, bound, effective

The standard

The effective sulfur fraction measures protection not by the total amount but by the molecular part of the free sulfur. How large it is depends on the pH value.

Criteria

  • Free and bound are determined separately, not as a sum
  • The pH value decides the molecular part
  • Only the molecular form acts against oxidation and microbes
  • The bound part is not available as protection

Distinction

Binding forms of SO₂ ≠ sulfites: sulfites are the substance, the binding forms its states in wine. Free sulfur ≠ total sulfur: only the free, molecular part protects. The effective sulfur fraction separates amount from effect.