Originally Posted by Tnuscan
If this question was for me, I would feel beter if this were the case. I really tested, then, calibrated and re-calibrated my pH meter to make sure it was accurate, using fresh calibrating solutions.
Yup that was for you. I'm sure the meter was reading a correctly. I've recently been working with two x 2.5 gallon batchs of Zinfandel and Blush Zinfandell from Canned concentrate. They both dropped in Acid readings in the first few days of fermentation. 24 hours before I started the fermentation I mixed up the concentrate, added the Simply Syrup solution to each batch and found that their pH readings were too high. One about 3.96 I believe and the other 3.80. So I adjusted them over the next 24 hours and finally pitched the yeast once I had them at 3.36 (Blush Zin) and 3.61 (Zin) The Blush snuck up on me but I decided to go ahead with the fermentation - even though I would have preferred a pH between 3.4 and 3.6 (I'd been careful add my acid blend and stir well then let it sit before readings were taken. )
So 3 days later once fermentation was clearly started I checked them both again. Blush Zin's SG had dropped from 1.082 to 1.066 and pH had dropped from 3.36 to 2.65 !!! The Zin's SG had dropped from 1.082 to 1.062 and the pH had gone from 3.61 to 3.05
Since both of these were straight concentrate juices with no skins or pulp the only thing I can figure is that the fermentation process frees up acid.
IF of course anyone has another explanation I'm always willing to learn. That's why I check in here daily and read all the new activity and comments.
At last check on 19th I racked them into 4 liter carboys with the following readings:
Blush Zinfandel SG .992 pH 3.06
Zinfandel SG 1.012 pH 3.28
So As I've seen in the past the pH readings moderate (Rise) as the fermentation finishes and should continue to moderate somewhat for the next month or two at least. I imagine someone can give us a better explanation for this but I suspect that it has something to do with the chemicals/acids that form and dissipate during the normal fermentation process. Again - ready to hear from the experts or more experienced folk on here.