Author Topic: Crazy pH drop during fermentation  (Read 1642 times)

Offline nateo

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Crazy pH drop during fermentation
« on: March 10, 2012, 05:36:57 PM »
I'm doing six 3L fermentation trials for mead right now, comparing different strains, trying my hand at Curt Stock's Even-speed-mead method, and also the effect of very hard water on mead. I'll do a more detailed write-up later, but the initial results were shocking.

OG: 1.050
500g honey
2g yeast (properly rehydrated)

A1 - 71B with hard water (400ppm CaCO3)
A2 - 71B with lime-softened water (50ppm CaCO3)

Day 0
Added 0.65g Fermaid K to both
Added 0.30g DAP

A1 pH - 5.9
A2 pH - 5.8

Day 1
Roused

Day 2 - SG: 1.030
Roused
Added 0.65g Fermaid
Added 0.30g DAP

A1 pH - 2.3. Added 1tbsp+1/2tsp of 5% calcium hydroxide solution, which raised the pH to 3.7
A2 pH - 1.8. Added 3tbsp of 5% lime solution, which raised the pH to 3.8

I degassed the samples by shaking them repeatedly in a mason jar, and also by letting them sit out for a few hours. I calibrated my pH meter was calibrated twice, to 7 and 4, because I didn't believe my results.

I really didn't expect the pH to fall that much that quickly. I'm not surprised at all that most mead fermentations take months to finish, since the must becomes so hostile to yeast so quickly.


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Offline hopfenundmalz

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Re: Crazy pH drop during fermentation
« Reply #1 on: March 10, 2012, 06:29:02 PM »
Water high in bicarbonates helps this, according to Steve Piatz.  Some add KCO3 to keep the pH in the range the yeast like.  A mix-stir is used when the nutrients go in, to aerate and to knock out the CO2.  Getting the CO2 out will also help the pH stay up.
Jeff Rankert
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Offline nateo

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Re: Crazy pH drop during fermentation
« Reply #2 on: March 11, 2012, 07:28:06 AM »
Water high in bicarbonates helps this, according to Steve Piatz.  Some add KCO3 to keep the pH in the range the yeast like.  A mix-stir is used when the nutrients go in, to aerate and to knock out the CO2.  Getting the CO2 out will also help the pH stay up.

I think it would take a lot of CO3 to get the pH into the proper range. It took a lot of Ca(OH)2, and that's a much stronger base than KCO3.

I wasn't surprised that the pH dropped, but I was amazed at how far it dropped, and how quickly it dropped. I think a lot of the stuck ferments homebrewers run into when making mead, wine, cider (and maybe beer?) could be due to low fermentation pH shocking the yeast.

I was thinking about how a lot of people add yeast to stuck ferments, and it made me think of locking a puppy in a hot car. The puppy died, and instead of rolling down the windows, you just shove more puppies in there, and hope one of them doesn't die.
In der Kürze liegt die Würze.

Offline ccfoo242

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Re: Crazy pH drop during fermentation
« Reply #3 on: March 11, 2012, 03:45:21 PM »
I was thinking about how a lot of people add yeast to stuck ferments, and it made me think of locking a puppy in a hot car. The puppy died, and instead of rolling down the windows, you just shove more puppies in there, and hope one of them doesn't die.

 :o

Best...analogy...ever...

Intra cervisiam est deus.

Offline bo

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Re: Crazy pH drop during fermentation
« Reply #4 on: March 11, 2012, 08:21:16 PM »
I was thinking about how a lot of people add yeast to stuck ferments, and it made me think of locking a puppy in a hot car. The puppy died, and instead of rolling down the windows, you just shove more puppies in there, and hope one of them doesn't die.

 :o

Best...analogy...ever...

True, but please use kittens next time.

Offline thcipriani

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Re: Crazy pH drop during fermentation
« Reply #5 on: March 12, 2012, 09:38:21 AM »
I'll do a more detailed write-up later, but the initial results were shocking.

I'm very interested in your write up. I've been using Steve Piatz's water recommendation from a recent zymurgy (200ppm hardness as CaCO3) but I don't actually add any carbonates to the water.

I adjust the must to pH >4 pre-ferment with 2N KOH and throughout fermentation (as per the 2008ish Kristen England NHC mead presentation). Never seen that dramatic of a drop in pH though.

Good stuff!
Tyler Cipriani
Longmont, CO

Offline nateo

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Re: Crazy pH drop during fermentation
« Reply #6 on: March 12, 2012, 09:52:47 AM »
I'm evaluating 71B's performance with hard v soft water, and also evaluating K1V, RC212, and Red Star Cote Des Blanc, and Premier Cuvee (with soft water). I plan on doing some more trials later with R2 and BM45, but my LHBS didn't have them in stock.

So far, it seems the pH drop is at least partially yeast dependent. I don't have a way to quantify how I'm degassing. I just swirl it around for about 30seconds. So the varying pH readings I'm getting from the different yeasts might just be operator error.

Also, the one jug with hard water had the closest thing to Krausen of the 6. I'm not sure how the water affected that. Maybe more nucleation sites or something?

I'm only on day 5 so far, but fermentation should be winding down soon. Most of the musts were around 1.010 as of yesterday.
« Last Edit: March 12, 2012, 09:54:53 AM by nateo »
In der Kürze liegt die Würze.