Abstract
The true endpoint of the total acid titration curve in wine seems to be quite close to pH 7.7. Utilization of this pH permits accurate determination of the endpoint electrometrically since the curve is steepest in this region and a small amount of titrant will shift the pH radically. In cases where a pH meter is unavailable, an excellent indicator, Cresol Red, which has a very distinctive color change at this pH, is available. Superior standard deviation figures are found for this analysis when Cresol Red is substituted for phenolphthalein. The answers obtained by titrating to pH 7.7 or the Cresol Red endpoint may be converted to those found with phenolphthalein or pH 8.4 by multiplying by a factor of 1.05.
- Copyright 1966 by the American Society for Enology and Viticulture
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