Kettle sours getting too sour

[nolasuperbass]

I took the advice of this forum and kettle-soured a batch with L Planarum. It worked like a beast, and got the pH down to 3.2 in less than 48 hours. The second time I used it, I was trying to keep it from getting quite that sour, so I reduced the dose from the recommended 5 pills (in 5 gallons) to 3, and reduced the temperature from a steady 105 degrees F to ambient summer garage temps (85-90 F). I got the exactly the same result, however, of 3.2 pH. I was wondering if there is an easy way to control the lacto better. It also occurred to me that I could sour only part of the batch, then blend it back together (after boiling the sour half, of course). I know the pH scale is logarithmic, so is there an equation to calculate blended pH's? Thanks in advance!

 

[bucketnative]

How about letting it sour for less time, maybe try 24 hours?

As far as blending, if you were to blend 50/50 you would need to account for the pH of both the sour and non-soured portions:
pHSour = 3.2 = -log10[H+]
[H+]Sour = 10^(-3.2) = 6.3x10^-4 mol/L

I am assuming that pHWort = 5.3 = -log10[H+]
[H+]Wort = 10^(-5.3) = 5.0x10^-6 mol/L

Now just blend like you would any other solution:

1L sour wort + 1L wort = (6.3x10^-4 mol H+) + (5.0x10^-6 mol H+)
Yields a total of 6.35 x 10^-4 mol H+ in 2L
So [H+]Blend = 3.18 x 10^-4 mol/L

pHBlend = -Log[H+]Blend = 3.5

 

[Dcpcooks]

If I remember correctly off color brewing in Chicago sours 25% of their gose overnight with lacto and boils and cools the next day. Then they transfer to the main fermentor that was pitched with sacc the previous day.

I believe that's based on kettle volume on hand and fermentor size and a hand full of experience

 

[coypoo]

Why not measure the pH at like 18, 24, and 36 hours. Once you get your desired pH, either boil then or if you don't have time at that exact moment, and some hops to buy you some time until you can boil

 

[505-Brewer]

Lacto grows fast. Plan on less time or blending.

 

[popquizkid]

I have had this problem as well. Part of the problem for me is being available to check the ph and then boil right when I need to. Weekends can sometimes be pretty busy having two young kids. Felt my kettle sours often were getting more sour than I like.

The last batch I did I approached it a little differently- more like an accelerated traditional fermentation and my Gose came out fantastic.
I cooled wort to 90 degrees and transferred to fermenter. Pitched good belly, purged head space with co2 and let the temp slowly ramp down in my basement. After about 16 hours it was at 76 degrees. Moved to ferm chamber and pitch wlp029 and some brett.

Did not measure PH (should have) when I pitched the sacch and brett - but its much less puckering (in a good way) than previous kettle sour batches. Maybe I just got lucky? I am aware that this method is not very scientific and there is some loss of control -- but it worked for me once at least