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| | | | SO2 Reduction - Peroxide method
Description: Has anyone had success with this procedure for reducing SO2 in wine?
SOP for addition of Hydrogen Peroxide.
- Determine the concentration of total and free so2
- Calculate concentration of so2 to be removed, leaving a 10% safety margin.
- Formula for calculating the amount of H2O2
H2O2 (ml) = .0014 x SO2 to be removed (ppm) x Tank Volume(L).
- .0014 = Takes into account the concentration of H2O2 solution and the mole ratio of H2O2 and So2 in the reaction.
- Conduct a bench trail to verify calcs. before treating the wine.
Procedures for addition in the cellar:
- Determine the volume of wine to be treated.
- Calculate the volume of H2O2 required.
- Measure out the calculated volume of 35% w/w H2O2, add 10 times the volume of
distilled water and mix well.
- Cover with inert gas any headspace in tank. Add the solution of H2O2 and water very slowly (drop by drop) into the wine while stirring thoroughly. (The slow addition with stirring prevents localized oxidation).
- After 3 to 4 hours determine the concentration of free and total so2.
- Assess if the required decrease in the concentration of free so2 has been achieved. If
not, repeat the exercise with a recalculated addition of H2O2.
Rating: N/A
Category: Winemaking (list all categories)
Manufacturer:
Submitted By: tmedeiros ,
Total Reviews: 1
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| | | | A Napa Valley client has had success with this method published by the Australian Wine Research Institute (AWRI). Please contact me for a .pdf of this procedure.
Technical Services Group Technical Note
TN06—Removal from and addition of sulfur dioxide to must, juice
and wine
Scope
A means of calculating the appropriate addition of hydrogen peroxide required to reduce the concentration of
sulfur dioxide (SO2) by a desired amount is described. Brief notes on techniques for the addition of SO2 to musts
and wine are also given.
1. Removal of SO2 from wine
A. Hydrogen peroxide
The removal of sulfur dioxide from wine using hydrogen peroxide (H2O2) is an effective, and if performed
carefully, safe procedure. The H2O2 reacts with the free SO2 in the wine, oxidising it to sulfate. After such
removal, further free SO2 may be generated from the remaining bound fraction.
The H2O2 should be added in a dilute form (recommend less than 1% w/v), slowly, with adequate mixing (e.g.
tank recirculation) to avoid localised oxidation. The wine should then be allowed to equilibrate for at least
several hours before confirmatory analysis of the concentration of remaining free and bound sulfur dioxide in the
wine is done to confirm the success of the addition.
The Australian Food Standards Code part P4 lists H2O2 amongst several legal additives. A copy of this document
is available from the Institute on request. It sets a maximum concentration of H2O2 permitted in wine of 1 mg/L,
and a maximum concentration of soluble sulfates at 20ºC of 2 g/L. The maximum concentration of total sulfur
dioxide is, at the time of preparation of this document, 300 mg/L (“for wines containing greater than 35 g/L of
sugars”; the limit is 250 mg/L for wines with less than this concentration of sugars); this is, along with all aspects
of the Standard, subject to review from time to time. The legality of H2O2 use varies from country to country;
and at the time of preparation of this document, it is not a permitted additive in the European Union, for
example.
The following guidelines detail how to calculate the quantity of H2O2 to add in order to remove a given
concentration of SO2. The Institute is happy to give further specific advice regarding the practical aspects of the
operation if required. Winemakers should be aware of the potential risks of a loss of wine quality associated with
hydrogen peroxide additions if care is not exercised. H2O2 is a strong, non-specific oxidising agent, and under
the conditions of use in wine it may have a limited effect on various other wine components.
1. Estimate concentration of free SO2 to be removed.
Allow a 10% safety margin. For example, if a wine has a free SO2 of 50 mg/L and it is desired to reduce
this to 25 mg/L, then 25 mg/L must be removed. However, it is wise to allow a 10% safety margin, so
calculate H2O2 addition on the basis of removing 22 mg/L.
2. Calculate corresponding amount of SO2
Multiply concentration of free SO2 to be removed by the volume of wine (L) in question. It is advisable
at this stage to divide the result by 1000 to express the answer in terms of grams (rather than milligrams).
3. Calculate corresponding amount of H2O2
- Molecular weight of SO2 = 64
- Molecular weight of H2O2 = 34
- Therefore, corresponding amount of H2O2 = 34/64
4. Express amount of H2O2 calculated as a measurable volume
The amount of H2O2 calculated above must be expressed in terms of volume, according to the strength of
the solution used. Commercial H2O2 is typically 30–35% w/v.
Date of Issue: 27 March, 20072007 Page 1 of 2 in Technical Note TN06—Removal from and addition of sulfur
dioxide to must, juice and wine
Authorised by: Wine Research 1
Technical Services Group Technical Note
5. Caution
- Never decrease the calculated free SO2 to less than 5 mg/L.
- Always allow for a margin of safety.
- SO2 will re-equilibrate in solution after a fairly short time. It is quite common to have to add H2O2 in
several stages in order to achieve the final SO2 concentration desired.
6. Numerical example: Removal of 25 mg/L SO2 from 1700 L wine.
- Calculate the amount of SO2 to be removed: 25 mg x 90% x 1700 L
= 38250 mg (= 38.3 g)
- Calculate corresponding amount of H2O2: 38.3 g x 34/64
= 20.32 g
- Express amount of H2O2 as a volume: Assume 35% w/v (i.e. 35 g/100 mL) H2O2 used
= 20.32 g x 100 mL/35 g = 58 mL
B. Yeast addition
If you wish to reduce the concentration of SO2 in juice prior to inoculation the use of a ‘sacrificial’ yeast cell
culture has been found to be quite successful. Please contact the Industry Services group for further information
(email: Con Simos@awri.com.au).
2. The addition of sulfur dioxide:
The addition of sulfur dioxide may be made using ‘pure’ sulfur dioxide (available as a pressurised liquid), as an
aqueous solution which may be prepared by bubbling gaseous SO2 into water, or as solid salts, which may be
dissolved in water or wine before addition.
The amount of SO2 added as an aqueous solution depends on the strength of that solution, and may be calculated
from its concentration, normally expressed as % weight/volume.
The two most commonly-used salt forms are potassium metabisulfite (K2S2O5, often abbreviated colloquially to
PMS and less commonly KMS) and sodium metabisulfite (Na2S2O5, or SMS). The proportion of SO2 in each is as
follows:
- PMS: 57 % w/w
- SMS: 67 % w/w
Note that the remaining proportions of these products are potassium and sodium salts, respectively; the addition
of these to wine may or may not be desirable.
Note that, as of 8 March 1995, sodium salts of oenological products such as casein and metabisulfite are
NOT permitted additives as additives to Australian wine. SMS may no longer be used as an additive to
wine.
Date of Issue: 27 March, 20072007 Page 2 of 2 in Technical Note TN06—Removal from and addition of sulfur
dioxide to must, juice and wine
Authorised by: Wine Research 2
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