I got my first acid test kit recently, but I guess I hadn't really absorbed how they work, and I discover to my dismay that because of my color blindness I am unable to make any kind of accurate determination of when the end color change has occured.
Can anyone recommend or discuss the alternative methods (if any) of acid testing for my homemade wines?
I occasionally see people here mention pH testing, but I was led to understand that pH testing was not completely appropriate to acid testing for wine.
As ever, the benefit of your experience and help is greatly appreciated.
Near the very bottom the author mentions, almost in passing, that one can use a pH meter to monitor the titration, using a pH endpoint of 8.2 for phenolpthalein indicator.
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
Posted Via Usenet.com Premium Usenet Newsgroup Services
Ah, doug, mine are few moments alone. I intend to keep my winemaking MY winemaking, even if I have to drink brash or insipid wine. No, no help except this newsgroup for me!
short answer: use a ph meter instead of the color change, it is more accurate anyway.
____________________________________________________________________ "To create robots that devour flesh is to step over a line that we would be insane to cross." - A Time Read re: The SlugBot
DrinksForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.