Hydrogen peroxide for reduction of sulphur dioxide

Discussion

Hydrogen peroxide can be used to reduce sulphur dioxide levels in a juice or wine. The reaction is the same as that used in the Rankine/Aspiration method for determining sulphur dioxide levels, namely the hydrogen peroxide oxidises the sulphur dioxide to form sulphate and hydrogen ions:

H₂O₂ + SO₂ => 2H⁺ + SO₄⁼

To calculate the required volume of hydrogen peroxide, first determine the reduction in total sulphur dioxide required.  The volume required is related to the strength of the peroxide solution, which is typically 35%, therefore this must be known. Finally, the volume of juice/wine must be determined. The volume of Z%w/w hydrogen peroxide (in mL) required to reduce the sulphur level by the required amount in (mg/L) in a given volume of wine (L) is calculated as follows:

Volume H₂O₂ = 0.049/Z x (SO₂ reduction) x (Volume juice/wine)

This should always be trialed before use, as the reduction may be affected by other factors.

Trials

1. Remeasure the sulphur levels in the juice/wine.
2. Measure 500mL of juice/wine into a beaker
3. Prepare a dilute hydrogen peroxide solution by diluting 35%w/w H₂O₂ by a factor of 10.
4. Calculate the quantity of peroxide required for 500mL of wine using the strength of the diluted hydrogen peroxide solution.
5. Add this dropwise with stirring to the juice/wine sample.
6. Wait 3-4 hours before re-measuring the sulphur levels in the wine and assessing whether the addition has been sufficient. If not, then recalculate proportionally the volume required, and conduct the trial again.

Cellar addition

When adding the peroxide in the cellar, the process is similar to that in the trials.

• The peroxide should be diluted at least 10:1 before addition
• The juice/wine must be stirred thoroughly (or the solution must be added using a dosing pump or during a pumpover/rummage.
• Wait 3-4 hours before re-measuring the sulphur levels.

Revised: November 22, 2003 .