snpm wrote:

> I read it, but I dont understand it at all. Im too thick for htat page
> Mike, but thank you much all the same!
Can't say I blame you. I've only skimmed the article myself, planning to
read it some nite when sleep eludes me.

The gist of it is two things:

1st: Total acidity is different from pH, and is probably the more
important measurement, tho some people differ. TA measures the full
amount of acids in the wine, but not all of that acid is in the active
or "dissociated" form. pH measures only the active form of the acid, and
that's what a pH meter shows us. Unfortunately, we can taste both active
& inactive forms of the acids, so we would want to know TA for gauging
the taste. pH just doesn't cut it for predicting taste, tho it's useful
for other things, like sulfite levels. There's no clear cut rule of
thumb for how TA & pH relate to each other; it differs in every case.

2nd: In your case, rather than looking for a color change of
phenolpthalein (indicator ) when you do a titration for TA, you can use
a pH meter to tell you when you get to the point that phenolpthalein
normally changes color. That pH point, for phenolpthalein, is 8.2 Just
do an ordinary titration, but with a pH meter in the beaker, and stop
when it reads 8.2. It's as if you went to the visual endpoint for
phenolpthalein. Many people do it this way anyway, as it's more precise
than relying on just how pink "pink" is.

(BTW, don't forget to microwave the wine sample to drive off the carbon
dioxide first. CO2 affects TA & pH.)

Another approach is to taste test and do bench tests to determine what,
if any, additions are needed. I tend to favor this approach after I've
gotten close by lab analysis.


Mike MTM, Cokesbury, NJ, USA

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