If you have a malo-lactic fermentation going at the same time as your
primary fermentation, the total acidity will change as the fermentation
progresses. You can sometimes end up with malo-lactic fermentation occurring
without intending too, since the bacteria responsible can be natrually
occurring. So, while you could get an accurate acid reading for that
particular point in the fermentation, it may not be "accurate" in the sense
of being stable over time.

I don't believe there's anything about the yeast fermentation process itself
that would cause a problem for determining total acidity by titration, or
with determining the pH with a pH meter.

However, if you are titrating and looking for a color change, that will
probably be easier after fermentation has completed and the wine has
cleared. If you're looking to maybe adjust the acidity by beginning a
malo-lactic fermentation, however, you may want to determine the total acid
level prior to the end of yeast fermentation, as the malo-lactic bacteria
like grape skins and other nutrients in the must as well as the heat
generated from the yeast fermentation. You can start the malo-lactic
fermentation later after the yeast fermentation has completed, but you may
want to also add some malo-lactic nutrient to help get it going.


"james" > wrote in message
om...
> Can one get an accurate acid reading on must that has begun fermenting?