Bruce Sinclair wrote:

> To paraphrase my earlier post, all (or most) reactions that occur in bottles
> are considered 'bad'. That's why many/most winemakers are now putting the
> vast bulk of their production into screw top bottles. The 'bad' reactions
> are reduced, and the wine tastes like they want it to. IME, this is a very
> good thing.

Not at all. Many reactions that take place in the bottle are desirable.
To use the most obvious one, the cross-linking of tannins (by at least
two different pathways) leads to the reduction of astringent flavors in
red wine and a more palatable beverage for most people. The deleterious
reactions mostly involve the unwanted ingress of oxygen, though an
ongoing debate concerns whether some amount of oxygen ingress is a
positive for the wine. To the extent that they control oxygen ingress
more effectively, screwcaps are a positive development in the sealing of
wine bottles.

Mark Lipton
(a wine loving Ph. D. chemist)