Alex,
Your process was pretty good, the only thing I would do differently is
make sure I still had 50 ml after the heating. Add distilled water if
necessary, then pull the sample.

Vacuum degassing or purging with nitrogen may work, but I'm not a
chemist so I can't say with certainty. Margalit suggests the heating
process you used, but uses a 100 ml sample size. His book Winery
Technology is great and under $30 US. Mine is pretty worn out.

You seem to have a lot of potassium in that must. The ratio of malic
falls and tartaric rises (since it does not fall) in mature grapes.
Adding tartaric as Tom and Bill suggest will pull the potassium out
and swing the pH better than malic so I would do that too. You really
do want to cold stabilize. 25 F is faster than 40 F, but winter is
coming and that could be an option too.

I'm not as experienced as Tom and still measure and use TA. It's
easier to understand and manipulate for me since the relationship is
linear, not a log function like pH.

It's also easier for me to correlate taste to TA than pH, I have never
had a dry red with a TA over 6g/l that I thought was balanced. It's
always too tart for me. OTOH I've had the pH all over the place (from
3.45 to 3.85) on wines I like with a TA under 6 and that's a big
difference (to me).

Taste is everything though, trust your taste over optimal values in a
book. The author is not drinking your wine...

)

Joe

"Alex" > wrote in message >...
> Joe,
> I did calibrate the meter just before use and I made up the .2 M NaOH
> from a 5 M stock that is only a few weeks old. I am not so certain I
> properly degassed the wine though. I had it in a 50 ml conical tube and
> microwaved it until it was hot (not yet boiling) and I saw a bunch of
> bubbles forming on the side of the tube. I then put 15 ml in a flask and
> swirled it around for a while and waited for it to cool off before I checked
> the pH and titrated the acid. I will definitely re check it, but if nothing
> terrible will happen to the wine in the short term I will wait for
> fermentation and ML to stop completely. There is still an occasional bubble
> coming out of the air lock.
>
> In case I get anxious or for next time , can the wine be degassed properly
> by putting it under a vacuum or bubbling nitrogen through it? I have both
> of these readily available and maybe it would be more certain than just
> heating it up?
> -Alex
> "Joe Sallustio" > wrote in message
> om...
> > Hi Alex,
> > That pH seems awful high for a TA in the range you are talking. That
> > sounds like a good Fisher Scientific or Corning pH meter, but are you
> > calibrating it right before the measurement and are you degassing the
> > sample? If so are you sure of the normality of your NAOH? If it
> > tastes tart the TA seems right...
> >
> > I take the sample to boiling for an instant prior to reading. CO2 can
> > make the pH seem falsely high.
> >
> > The right way to do it is to measure out at least 50 ml of sample,
> > degas, add distilled water back to 50 ml if necessary, cal the meter,
> > measure pH and titrate acid.
> >
> > Joe