"Mike McGeough" > wrote in message
...
> 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

Thank you for a great post Mike.
Lum
Del Mar, California, USA
www.geocities.com/lumeisenman