Tom S wrote:


> Hi, Mark -
> While that's true, I suppose, there are a couple of things I don't
> understand about tartrates:
> (1) If KHT contributes to the "crispness" of a wine (presumably by
> providing hydrogen ions) why is it tasteless all by itself?

Well, it could serve to protonate malate, thereby producing a tart malic
acid. By this logic, just acidifying your wine with HCl (Not A Smart
Idea, BTW) should achieve the same results.

> (2) IIRC, cold stabilization moves the pH in _opposite_ directions,
> depending on whether the wine started above or below pH ~3.6. Why wouldn't
> it _always_ cause the pH to rise if fewer hydrogen ions are available due to
> the removal of KHT?

Aha! Looking in my handy CRC Handbook, I find that the first ionization
constant of tartaric acid is 3.22 in water. Therefore, if your pH is
_below_ 3.22, KHT is acting as a _base_, not an acid. Loss of KHT
removes a base, rendering the wine more acidic. Cool, huh? ;-)

Mark Lipton