I followed the wort souring method to obtain a sour mash that I intend to boil and referment with a lager yeast. Batch is only 10 liters (2.5 Gallons) The trouble is that I was busy for a short period and instead of allowing for only 2-3 days of souring at 44 C° (111 F) it has been souring for approx 5 days. Now the PH has dropped to 2.4 well below the advised 3.4 for a Beriner Weisse. The wort has a nice clean smell of baked bread with no nastiness (it does not even smell sour). My question is: Could I add the equivalent of water and malt extract during the boil to raise the PH ? What proportions would be needed to bring it to 3.5- 3.7 (but no higher) ?
Are you certain the pH is that low? Even using strains of L. plantarum usually you can only bottom out around 3.3 or so with that short of a growth period. I would imagine if your pH was 2.4, regular year would not survive in that environment at all. Additionally, you probably could just add a little baking soda to fix the high pH, but I would have to go back to my old text books to remember the amount needed.
Humm.. I thought also that 2.4 looked a bit unrealistic. I used an electronic ph meter. I measured plain water before testing and it gave me 6.9, which is likely to be correct. I have to say that I used acid malt at about 15% to mash and also about half pound of the same to develop lacto. So I guess that started souring probably at already below 4.5. But 2.4 is ... well suprising. I checked with an online chemistry calculator and it says that if I added the same quantity of water, I would go up at barely 3.0 PH
A few points. First, sorry for not responding earlier, this advice might be too late. Second, @Brewday makes a good point, and I would add that even taste is going to be deceptive at this point. With the sweetness still in the wort, the sourness will be balanced and will seem much more muted than it will in the final product. So basically what I am saying is, assume that the perceived sourness will be considerably higher in the finished product than it is now. Third, look, you have a pH meter. To be completely honest I harbor doubts as to its accuracy, but let's put that aside. Assume you trust your pH meter. Why not, you know, add water and DME until the pH is in the range you want? It may not be perfect, but perfection hasn't been on the table for a while now. (This should be done at room temperature so as not to damage your pH meter.) [Edited to add: Part of my skepticism as to your meter is that I don't fully understand what you mean about testing it by measuring a water pH of 6.9. That could be the pH of your water, but do you have reason to believe that? When is the last time you calibrated the meter using buffered solutions (7.0 and 4.0 pH)? Unless you have reason to be confident in your instrument, it seems to me the most likely explanation here is a faulty pH reading.] Finally, I think a completely valid option here would be to let it ride and ferment with a yeast that is tolerant of low pH. I don't know about lager yeast. I believe that saison yeast and 100% brett fermentations are feasible. There was recently an article on this in BYO, by the way. Good luck!
You are right, I need to taste and worry less about perfection. Definitively there should be something wrong with that PH meter. I'll go forward and boil the wort this evening and add more water (OG is 1.052 which is way too high for a berliner weisse anyway) I don't have a specific low ph yeast, but I do have: - WLP001 California Ale ; - WLP648 Brettanomyces bruxellensis Trois Vrai, - WLP650 Brettanomyces bruxellensis, - WLP653 Brettanomyces lambicus, - WLP655 Belgian Sour Mix 1, and a nearly finished batch with French Saison that I can put into secondary and re-use the yeast cake So plenty of choice ;-) I will let you know of the outcomes of my experiment
You have some good options there. Personally I would go with the WLP648, but I believe the other bretts would work fine too. The French saison would work, I think, but the thing about the saison yeast is that you might end up with a very thin beer, since you are starting from such a low gravity.
