"gene" > wrote in message
om...
> but, Tom......
> I thot the tannins extracted from the skin and seeds in red wine made them
> more tolerant of small amounts of oxygen.

The operative word is "small". Although red wines are more tolerant of
oxygen exposure, they are every bit as susceptible to microbial spoilage as
whites. The spoilage organisms need oxygen to propagate, so the idea of
topping up is to cut off their air supply. Sulfite reacts with oxygen
dissolved in the wine to cut off the air supply from that direction, but you
really need to tend to both maintaining minimal headspace _and_ an adequate
sulfite level.

Tom S