How Does Saccharomyces C. Affect the pH of Kettle Soured Wort During Fermentation?
We're going to do our first kettle sour this summer (a traditional Berliner weisse), and we're trying to better understand how a saccharomyces cerivisiae fermentation will affect the pH of our kettle soured wort over the course of fermentation. We're going to shoot for a post-souring pH of 3.0 (we plan to blend the soured batch with a non-soured batch to hit a target overall pH of around 3.6). Our typical s.c. fermentations yield a finished beer pH between 4.2 - 4.4, depending on the beer and the strain. In any case, should we expect the pH of the kettle soured beer to finish within our typical s.c. fermentation range (i.e., 4.2 - 4.4), or will the kettle soured beer exhibit some other pH change during fermentation? Alternatively, should we not expect the pH to change much at all as a result of the s.c. fermentation?
Thanks in advance,
Last edited by Matt@Bauhaus; 03-13-2017 at 05:55 AM.
We have done a handful of kettle soured Berliners both with 1056 and saison-type strains. Using Omega Labs lacto blend at 95°F in a CO2-blanketed kettle we have always ended up around 3.25 - 3.35pH within 24 hours, sometimes much quicker, more like 16 hours. We increase our nutrient addition when we boil the wort and have pitched at 1.5 million/ml/°P in an effort to give the sacchro. the best chance we can to quickly and cleanly ferment. Our post-ferment pH's have more or less stayed where they were after the souring - maybe dropping a tenth of a point at the most.
Your results may vary depending upon the strain you ferment with but to respond to your base question, yeah, I would expect little change in the pH and probably not a rise.
I'm interested to hear other's results on this topic as well, especially with other lacto and yeast strains.
Last edited by BemidjiBrewing; 03-13-2017 at 09:51 AM.
Thanks, Tom! Much appreciated. We're likely going to pitch Weihenstephaner for the sacc fermentation, but a saison-type yeast could also be cool. In any event, your comments provide a helpful perspective!
Originally Posted by BemidjiBrewing
I will have to echo what Tom said.
I've only used 1056 for my Berliner but I haven't seen any drastic change in pH from fermentation. .1 to .2 up or down, enough to be measured, but not enough to affect the taste of the beer. Ferment times have always been about normal despite the lower pH. I do add extra nutrient in the boil and pitch at about 1 million/mL/p though.
I've never tried blending a sour and not sour batch before, I would suggest that you use extra nutrient and pitch well if you're fermenting around 3.0 pH, that seems like it will put a fair bit of extra stress on the yeast.
We have done quite a few kettle sours, both with American ale yeast, and multiple English yeasts. I find that usually the Sacch fermentation further drops the ph a small amount pretty consistently. So for example if we're around 3.45 after kettle sour, we'll usually see somewhere in the 3.38-3.42 range after fermentation.
I would be interested to find out if that blending idea works well. I am personally wary of blending kettle sour beer with normal beer for the simple reason that the kettle souring process naturally causes that dry thin mouthfeel that I usually expect in a sour. I don't know if It would be possible to nail that with blending normal beer. But then again I've never tried it.
Last edited by Junkyard; 03-19-2017 at 08:38 AM.
Two things of note: 1) Don't plan on reusing the yeast after fermenting the kettle sour - the conditions are super harsh and the yeast really aren't suited to fermenting properly after that. 2) Don't know if you've done test batches, but when we fermented our kettle soured wort with WLP300, it turned our SUPER grapefruity. Something about the acid changed the ester profile completely. If that's something you want, then cool. If not, take it into account. This was, however, only one time - used different yeasts after that, so I can't confirm that that will happen every time with a hefe strain. Good luck!
Originally Posted by Matt@Bauhaus