Mike Tommasi wrote:
> Yes, cognac is made almost entirely from Trebbiano grapes picked early
> (for some reason, distilling requires wine with high acidity, anyone
> know why?).

Fascinating question, Mike. I would hazard a guess that its another
facet of the observation that more highly acidic wines tend to age
better (within limits, of course). I suspect that the high acidity
helps protect the wine from extreme maderization during the distillation
process by partially suppressing oxidation. (Acids slow the oxidation
of the phenolics in wine by keeping the phenols protonated).

Just my (somewhat educated) guess,
Mark Lipton