More for this discussion. Several years ago I cold stabilized a Vidal
wine. There was a dramatic drop in pH. Ed Goist, who used to post valuable
information here, sent me the response given below. Pretty neat stuff.

Bill Frazier
Olathe, Kansas USA


From Ed Goist, February 2001
In wines with 11 to 13% alcohol cold stabilization will affect pH as
follows;

start pH pH change due to cold stabilization
3.20 or less noticeable, substantial decrease in pH
3.21-3.40 slight decrease in pH
3.41-3.60 very minimal change in pH
3.61-3.75 slight increase in pH
3.76 or more noticeable, substantial increase in pH

This is because of the pKa for potassium bitartrate of 3.55
bitartrates are effectively an alkaline substance for a wine with an
overall pH of 3.5 or lower,
and they are effectively an acid substance for a wine with an overall
pH of 3.6 or higher.

When tartrates are removed from wine with a very low pH, an alkaline
constituent is
effectively being removed and a greater proportion of acid
constituents overall will be
dissociated. This will cause the pH to decrease.

When tartrates are removed from a wine with a very high pH, an acidic
constituent is
effectively being removed and a smaller proportion of acid
constituents overall will be
dissociated. This will cause the pH to increase.