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Topic: Oxidation of white wine - How sulphur dioxide is effected  (Read 3688 times)

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Offline qwerty123

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Oxidation of white wine - How sulphur dioxide is effected
« on: June 12, 2011, 01:30:53 AM »
Hi, hoping someone will be able to clarify for me  :)
I exposed white wine to the atmosphere for 7 days. Through titration, it was revealed that SO2 content decreased within this time. As SO2 in wine exists as a dynamic equilibrium
(SO2 + H2::equil:: H+ + HS04-  ::equil:: SO3--)
This would mean that a few SO3-- would dissociate due to oxidation (I found this out through research - http://www.drinksforum.com/winemaking/pH-and-oxidation-1045-.htm)
And the reaction, due to Le chatelier's principal would shift from left to right.
However, I am not sure why SO3-- would be oxidised, opposed to the other forms of SO2 and how it is oxidised (represented by an equation).

Offline Borek

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Re: Oxidation of white wine - How sulphur dioxide is effected
« Reply #1 on: June 12, 2011, 06:07:26 AM »
Information on the page you linked to - while no completely off - doesn't look OK to me.

Wine oxidation means oxidation of ethanol, when it is oxidized to acetic acid, pH goes down. No need for SO2 in this process. Actually SO2 is there to slow down the oxidation, as it help keep amount of bacteria responsible for oxidation down.

Sulfite can be oxidized to sulfate, but this is a very slow process.
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