I recently got a pH meter and want to use it also as a titration indicator for
TA measurements. I would have supposed that the desired endpoint pH would be
7.0 (neutral). However, I have found one reference that says to use 8.1 - 8.2
as the endpoint. Another reference says that it is conventional to use 8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA that I
really want to use? Dennis

"D. J. Gooding" wrote in message
...

I recently got a pH meter and want to use it also as a titration indicator
for
TA measurements. I would have supposed that the desired endpoint pH would
be
7.0 (neutral). However, I have found one reference that says to use 8.1 -
8.2
as the endpoint. Another reference says that it is conventional to use
8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA that
I
really want to use?

If I remember correctly, the 8.2 pH number comes from where phenolphthalein
changes from colorless to pink.

FWIW, I haven't even bothered to measure TA on my wine/juice/must for the
past 15 years or so. I watch the pH very carefully though. That's the
number that really counts in the long term.

Tom S

Hi: The titration curve is very steep at pH7 so there is very little
difference between 7 or 8.2. The latter is the accepted value/

Joe
"D. J. Gooding" wrote in message
...

I recently got a pH meter and want to use it also as a titration indicator
for
TA measurements. I would have supposed that the desired endpoint pH would
be
7.0 (neutral). However, I have found one reference that says to use 8.1 -
8.2
as the endpoint. Another reference says that it is conventional to use
8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA that
I
really want to use? Dennis

8.2 is accepted in North America, 7 is accepted in Europe. As
mentioned by others, there is not much of a difference. If France,
they titrate as if it were sulfuric also as I recall. Most other
countries titrate as if it were tartaric.
Regards,
Joe

(D. J. Gooding) wrote in message ...
I recently got a pH meter and want to use it also as a titration indicator for
TA measurements. I would have supposed that the desired endpoint pH would be
7.0 (neutral). However, I have found one reference that says to use 8.1 - 8.2
as the endpoint. Another reference says that it is conventional to use 8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA that I
really want to use? Dennis

"Tom S" wrote in message
...

"D. J. Gooding" wrote in message
...

I recently got a pH meter and want to use it also as a titration
indicator
for
TA measurements. I would have supposed that the desired endpoint pH
would
be
7.0 (neutral). However, I have found one reference that says to use
8.1 -
8.2
as the endpoint. Another reference says that it is conventional to use
8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA
that
I
really want to use?

If I remember correctly, the 8.2 pH number comes from where
phenolphthalein
changes from colorless to pink.

FWIW, I haven't even bothered to measure TA on my wine/juice/must for the
past 15 years or so. I watch the pH very carefully though. That's the
number that really counts in the long term.

Tom S

Tom
I, like you, have started to rely more on pH. I posted a question to the
group a couple weeks ago but never got a response. The question is: Does
the pH change once the wine is bottled? I assume it does because there are
some chemical changes taking place during the aging process. I am just
trying to get some handle on what is happening and how to possibly get
longer shelf life from my wines. Typically, I have found that my red wines
are best between 18 months and three years, but I have been keeping track of
the pH of my unbottled wines recently and wonder if proper pH control before
bottling could lengthen shelf life.

Tom,

I realize the importance of pH to the stability of the wine,
particularly SO2 requirements but don't understand why you don't monitor
TA as well. Everything I've read suggests that TA determines the
acidity taste by 10 to 1 over pH. In the event of a must with the pH in
the "normal" range and the TA much higher don't you risk a wine that is
too acidic tastewise. For example, I now have a Riesling-Geisenheim
blend that is almost fermented out and has a pH of 3.29 and a TA of 11.2
g/l which I think is too high so I'm inclined to lower the TA to at
least 9.0 keeping in mind that I am making an off-dry wine.

Of course the taste-test is always important but it is difficult to
sense the acidity by taste until it is fermented out somewhat.

I'd be interested in your thoughts particularly on the TA of my blend.

Cheers,

Glen Duff
---------------------


Tom S wrote:

"D. J. Gooding" wrote in message
...

I recently got a pH meter and want to use it also as a titration indicator

for

TA measurements. I would have supposed that the desired endpoint pH would

be

7.0 (neutral). However, I have found one reference that says to use 8.1 -

8.2

as the endpoint. Another reference says that it is conventional to use

8.2 in

the US and 7.0 in France. Does anyone know why? Which yields the TA that

I

really want to use?


If I remember correctly, the 8.2 pH number comes from where phenolphthalein
changes from colorless to pink.

FWIW, I haven't even bothered to measure TA on my wine/juice/must for the
past 15 years or so. I watch the pH very carefully though. That's the
number that really counts in the long term.

Tom S

From a pure chemistry standpoint, titration to pH=8.2 will yield the more
"correct" value for TA. The reason is that wine is a buffered solution.
When you titrate using NaOH, you are neutralizing the weak organic acids in
the wine (Tartaric, Malic, Lactic, etc.) with a strong base, namely NaOH
(Sodium Hydroxide). The result of this neutralization reaction is things
like Sodium Tartrate, Sodium Malate, etc. These compounds are referred to
as salts. A salt that is formed from a strong base and a weak acid will
itself be slightly basic (pH7.0), likewise, the salt of a weak base and a
strong acid would be slightly acidic. During titration, you are
neutralizing the weak acids and forming salts which are slightly basic. So,
when you have neutralized all the organic acids in the wine by titration
(which is the definition of determining Total Acid (TA)), all you have left
is a bunch of salts of weak acid/strong base which are slightly basic and
give a pH~8.2, slightly basic.

CHEERS!

"Tom S" wrote in message
...

"D. J. Gooding" wrote in message
...

I recently got a pH meter and want to use it also as a titration
indicator
for
TA measurements. I would have supposed that the desired endpoint pH
would
be
7.0 (neutral). However, I have found one reference that says to use
8.1 -
8.2
as the endpoint. Another reference says that it is conventional to use
8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA
that
I
really want to use?

If I remember correctly, the 8.2 pH number comes from where
phenolphthalein
changes from colorless to pink.

FWIW, I haven't even bothered to measure TA on my wine/juice/must for the
past 15 years or so. I watch the pH very carefully though. That's the
number that really counts in the long term.

Tom S

Thanks for the help everyone. Dennis

In article , says...


I recently got a pH meter and want to use it also as a titration indicator for
TA measurements. I would have supposed that the desired endpoint pH would be
7.0 (neutral). However, I have found one reference that says to use 8.1 - 8.2
as the endpoint. Another reference says that it is conventional to use 8.2 in
the US and 7.0 in France. Does anyone know why? Which yields the TA that I
really want to use? Dennis