Something in the post and messenger for you? "Ben Rotter" wrote in message news: snipped-for-privacy@posting.google.com... | Greg Cook wrote: | | > I think the difference between pH 7 and 8.2 | > during the titration is a matter of just a few drops anyway (the titration | > curve is very very steep at the point of neutralization of the acids). | | Theoretically, that's true and I always assumed there'd be little | difference. I haven't done enough comparisons to accurately judge, but | I actually just read a paper recently which suggests this difference | *is* significant. | | In the paper [1], they compared the OIV method (titrate to pH 7.0, 50 | ml wine) and the AOAC method (titrate to pH 8.2, 10 ml wine diluted | with water to 100 ml) for 30 wines. They found no significant | difference due to operative technique (i.e. the dilution and sample | sizes), but they did find a difference due to pH end-point. This | difference correlated to a TA difference of 0.6 g/l (as tartaric) for | reds and 0.5 g/l for whites. Well, I consider that significant. | | BTW, if the standard was to titrate to the actual equivalence point | for wines, we'd all be titrating to pH's of around 10. In the purely | practical sense, I'm glad we have a standard at pH 7/8.2. Certainly | saves on the NaOH ;-) | | Ben | | [1] Darias-Martín, J. et al. (2003). Comparative study of methods for | determination of titrable acidity in wine. J. Food Composition and | Analysis 16, 555-562.