I use grocery store distilled water to dilute wine samples for acid titration and to replace lost volume when I boil off CO2 from samples of wine after fermentation, acid reduction by addition of bicarb, etc. There's been some discussion about this lately so here's the results of a Saturday morning experiment.
I use a Presque Isle titration kit, PI buffers and sodium hydroxide solution. I have an Omega PHH 78604 pH meter with new probe this summer.
Effect of distilled water on wine pH; When I boil off CO2 I replace the lost volume with distilled water and then test pH and TA. Dilute some Brew King Super Tuscan wine with various volumes of distilled water and test pH.
100% wine - pH 3.36 90% wine - pH 3.34 75% wine - pH 3.31 50% wine - pH 3.28The grocery store distilled water has a pH reading. A freshly opened gallon bottle started at pH 7.5 and drifted slowly down to 5.37 over a 5 minute period. So, it has some acidic properties. Looks like the more distilled water you add to a sample the more it effects pH and the trend is to give lower than expected readings.
Effect of distilled water on wine TA; When I do TA titrations I dilute wine samples with 100 to 200ml distilled water. I don't measure this water and eye ball the amount in my beakers. Test the BK Super Tuscan samples and compare to theoretical. Titrate to pH
8.2 for end point. I measured the distilled water for this experiment.100ml distilled water, no wine - required 1 drop NaOH solution (0.05ml)
200ml distilled water, no wine - required 2 drops NaOH solution (0.01ml)100% wine, 100ml distilled water dilution ~ 4.60ml NaOH, 0.69%TA
100% wine, 200ml distilled water dilution ~ 4.55ml NaOH, 0.68%TA 90%wine, 100ml distilled water ~ 4.0ml NaOH, 0.60%TA (theo. 0.62%) 75% wine, 100ml distilled water ~3.35ml NaOH, 0.50%TA (theo. 0.52%) 50% wine, 100ml distilled water ~ 2.2ml NaOH, 0.33%TA (theo. 0.35%)I thought I might have to routinely run a blank and subtract the volume of NaOH solution required to neutralize the distilled water from that used for the wine samples. But the volume is so low it won't make a practical difference. In this experiment there is a negative bias for actual TA measurements compared to the theorectical. You would think if the acid nature of distilled water made a real difference the bias would be on the positive side.
Bill Frazier Olathe, Kansas USA