In article >, BobF > wrote:
>Doug Miller wrote:
>> In article
> >,
> wrote:
>>
>>> [...] After fermentation, the wine will be full of CO2 ( fizzy). The CO2
> will
>>> protect the wine as long as you keep the wine topped up in th
>>> container you keep it in.[...] After ferment you could wait to add SO2
> because if you keep the
>>> wine topped up, it is saturated in CO2 so there is no panic to add it.
>>
>> Not sure I understand/agree with the above. The purpose of having SO2 in the
>> wine is to protect the wine from oxidation; this works because SO2 is readily
>
>> oxidized to SO3, and thus any oxygen present will react with the SO2 instead
>> of with the wine. This does *not* happen with CO2, though. CO2 is already as
>> oxidized as it's going to get, so it's difficult to see how the presence of
>> CO2 confers any protection against oxidation or anything else.
>
>The only protection I can think of is at the surface - perhaps a
>blanketing effect as co2 is heavier than atmosphere.
>
>OTOH, co2 will do nothing to protect the wine from oxygen once the
>oxygen gets into the wine. That's what the so2 is for.
Exactly so. There will be a layer of CO2 at the top of the vessel during
primary fermentation, and it will remain there until the vessel is disturbed
for racking. The same thing happens during secondary fermentation; again, the
layer of CO2 remains until the wine is racked. After that, though, the head
space in the vessel is filled with air, not CO2. Some CO2 will come out of
solution, but not much, not nearly enough to displace all the air. Dissolved
CO2 confers no protection against oxidation.