I wonder if it's sulfites; hydrogen sulfide is removed from drinking water by aeration.
Jeff
I've noticed with several wines that after a glass is poured the wine
> may go down very nicely, but after the glass has sat still for a few
> minutes the next sip will start as well as before, but will have
> developed a strong after-bite at the back and center of the tongue
> where it meets the throat.
>
> If, however, the wine is swirled gently in the glass a round or two
> before the next sip the after-bite is greatly deminished.
>
> Not tannins and not carbonation. I don't think it's acid.
>
> What is it? Esters?
>
> Since beginning to try wine making I've also begun to pay a lot more
> attention to what might be the actual components of the whole making
> up wine. This one has me stumped. Glad to have discovered a simple
> swirl can make such a nice effect.