Sour Mash: Lacto preferred pH

[Matt3989]

I've been searching around and I can't seem to find too much info on this. I'm wondering what the optimum pH for lacto is, I've read 3.4 to 5.

The reason for my questions is I'm about to do a sour mash for a Berliner Wiesse and I've read that to decrease your chance of an unwanted infection you should drop the pH a bit (and consequently, that makes the mash a better environment for the lacto).

 

[kbindera]

I'd worry more about temperature then pH. The lacto will lower the pH of your wort and you want it to do this as fast a possible. You'll need to keep the wort in the 110F range to promote that growth. You also want to make sure that you don't let the lacto go too far or you will give your yeast a hard time (I'm assuming you are souring the wort then pitching yeast).

I know in various vegetable ferments that a pH of 4 is considered a good target for safe long term storage. Just mentioning this since you mention "unwanted infection" and I am assuming that you are concerned with keeping bad bacteria out of your environment. For example, when I do my sauerkrauts, I target a pH of 4 and I can just leave it in jars unpasteurized for long periods of time.

The other thing to consider is just how sour you want to go. For me, when food or beer get much below 3.5 I start to feel like I am drinking vinegar. That's just me.

 

[Matt3989]

Temp is not a problem, that's easily regulated and everything I've read had consistently said between 100 and 126 for lacto in a sour mash. I also plan on purging most of the oxygen out of my water by boiling first since lacto is anaerobic, but most other bacteria need O2.

For the style, I'm trying to land the final pH between 3.0 and 3.2, but I'm concerned that lowering the mash to 4 might make it too hard on the yeast (US-05) to finish the fermentation.

 

[dantheman13]

Temp is not a problem, that's easily regulated and everything I've read had consistently said between 100 and 126 for lacto in a sour mash. I also plan on purging most of the oxygen out of my water by boiling first since lacto is anaerobic, but most other bacteria need O2.

For the style, I'm trying to land the final pH between 3.0 and 3.2, but I'm concerned that lowering the mash to 4 might make it too hard on the yeast (US-05) to finish the fermentation.

I've read Oldsock say that below 3.5 pH the Sacch can be highly stressed.

I've had good luck with pre-souring my wort with Lacto for 7 days and adding US05 (rehydrated with Go-Ferm), but I didn't take a pH reading so I am not sure how low it was. The beer turned out very sour in the end though.

 

[Sleepyemt]

The brewing network interviews Chad Yakobson of his petite guava which is a no boil, he talks about getting his PH down to 4.5, to help keep other bacteria out. The talks start around an 1:50:00

 

[Oldsock]

The brewing network interviews Chad Yakobson of his petite guava which is a no boil, he talks about getting his PH down to 4.5, to help keep other bacteria out. The talks start around an 1:50:00

Good advice, lowering the pH also helps inhibit a protein-destroying enzyme that Lacto produces (per Prof. Burghard Meyer of the VLB). Lowering the pH like this is a good idea anytime truly wild microbes are involved, it stops E. Coli et al. from thriving.

 

[Matt3989]

That sounds like a good point to try first. I'll lower the pH of the mash down to 4.5 and the temp down to 120 while I let the lacto work for 2 days before the boil.

Any idea how that lacto will affect the pH over those two days?

Since beer normally finished around 4, or possibly 3.5, I'm thinking the us-05 will do just fine fermenting it after the boil. Especially considering it's only a 1.030 beer...

Any other tips? I'm going to start the mash on Thursday or Friday, I'll let you know how it goes.

 

[Orangetones]

This is the response I got from Wyeast when I asked about using Pacman for a secondary ferment after an initial pitch of lacto a few days earlier. FWIW, I soured my entire wort with lacto from grain, held the temp at 46*C and after 2 days I was down to 3.5pH. After a boil it was measured at 3.4. The sacc yeast will produce some acid and drive the pH down further. From what Jess says, sacc yeast should be fine at those pH levels.

________________________

Yeast is definitely happier at higher pH levels, but most can grow down to low 3s, high 2s. The old pacman should work… it just may take a little longer to finish it out if it doesn’t like the low pH.


Jess Caudill
Brewer/Microbiologist
Wyeast Laboratories, Inc.