Author Topic: PH Increase Post-Boil vs Pre-Boil  (Read 971 times)

Offline UnequivocalBrewing

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PH Increase Post-Boil vs Pre-Boil
« on: June 23, 2017, 03:09:00 AM »
I've never measured PH throughout the entire process but thought I would tonight.  Here are the PH numbers:
Mash PH:  5.16   (15-20 minutes after start of mash)
Pre-Boil PH:  5.17 (after fly sparge)
Post-boil PH:  5.9

What the hell happened?  What would cause an increase in PH?  Has anyone ever seen this before?

Grain bill was simple 100% maris otter.  Hop schedule was just a bunch of Cryo hops for a 15 minute hop stand at flameout.  Nothing else. 

Could the trub and hop oils from the hop stand be impacting the readings?  Or is this something process oriented that's increasing PH? 

Offline UnequivocalBrewing

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #1 on: June 23, 2017, 05:43:25 PM »
A couple more things about my process, to help:
1.  I have a stainless steel basket I put my hops into so it doesn't clog up pumps, etc.
2.  I added 1.25 teaspoon per gallon of Fermax at 15 minutes left in boil
3.  No kettle fining agents
4.  At flameout I run out of the kettle into my chugger pump,  into my dudadiesel plate chiller, and back into my kettle.  Last night I did a 15 minute whirlpool with the Simcoe Cryo before turning on the water to chill it down.  Chill down took about 10 total minutes.

So I am really scratching my head here.  Between the time I start the boil until the time I am knocked out, my wort picked up some alkalinity causing 6/10th of an increase.  What could cause this sharp of an increase?  Chiller?  Pump?  Fermax?  Could the stainless steel basket and/or kettle be picking up caked on alkalinity over usage?

And I think it's a systemic problem because I measured my latest IPA which tasted flabby and it measured for a final PH of 4.7 next to a Treehouse beer of 4.3.

Offline UnequivocalBrewing

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #2 on: June 24, 2017, 12:07:23 PM »
I'm thinking the only thing that makes sense is the fermax.  I added 1.25 teaspoons of fermax at 15 minutes left in the boil. 

What do the chemistry experts think?

Offline mabrungard

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #3 on: June 26, 2017, 12:45:34 PM »
Why are you adding Fermax? An all-malt wort does not need any additional nutrients.  But back to the question, I don't know if that stuff raises pH.
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Offline brewinhard

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #4 on: June 26, 2017, 05:53:11 PM »
Why are you adding Fermax? An all-malt wort does not need any additional nutrients.  But back to the question, I don't know if that stuff raises pH.

I don't add fermax, but almost always add 1/2 tsp of Wyeast nutrient (per 5 gallon batch) to my beers and have never seen an INCREASE in pH like that.

IIRC, there was someone else who was experiencing this as well a while back.

Offline zwiller

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #5 on: June 26, 2017, 06:27:27 PM »
Based on your other thread I'd say the meter is wonky, possibly bad electrode or maybe bad calibration solution.  That's a HUUUGE change.  I predict the beer is fine...
Sam
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Offline brewinhard

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #6 on: June 26, 2017, 06:35:03 PM »
I've never measured PH throughout the entire process but thought I would tonight.  Here are the PH numbers:
Mash PH:  5.16   (15-20 minutes after start of mash)
Pre-Boil PH:  5.17 (after fly sparge)
Post-boil PH:  5.9

What the hell happened?  What would cause an increase in PH?  Has anyone ever seen this before?

Grain bill was simple 100% maris otter.  Hop schedule was just a bunch of Cryo hops for a 15 minute hop stand at flameout.  Nothing else. 

Could the trub and hop oils from the hop stand be impacting the readings?  Or is this something process oriented that's increasing PH?

Don't mean to ask a stupid question, but I am assuming you cooled your post boil final pH sample?

Offline UnequivocalBrewing

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #7 on: June 27, 2017, 01:50:30 AM »
I really do not think it's the probe.  It's a fairly new probe and it's reading quickly.  And yes every PH reading I take is at room temperature.

Martin - I think it's fairly common practice to add some additional yeast nutrient even in all grain brewing. I think I'm just dosing at like 10x the rate I should be.

Check out this thread...fermax has diammonium phosphate as one of the primary ingredients:

https://en.wikipedia.org/wiki/Diammonium_phosphate
DAP is used as a fertilizer.[4] When applied as plant food, it temporarily increases the soil pH

I'm going to rebrew the exact same recipe and add no fermax and measure PH throughout again. 

Offline thcipriani

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Re: PH Increase Post-Boil vs Pre-Boil
« Reply #8 on: June 28, 2017, 05:17:53 PM »
I've definitely had pH rise by several 100ths of a unit during mash and boil so 5.16 up to 5.17 over the course of a mash doesn't seem atypical but the jump to 5.9 at the end of the boil is kind of huge :)

I would expect the wort to have some buffering power against DAP.

Some questions to help troubleshooting:
  • Did you calibrate the meter on brew day?
  • Did you check against a reference solution before/after each reading?
  • If so, when was the reference solution prepared? Was it fresh?
  • What did you add to the mash to drop the pH? 5.16 is pretty low for 100% MO in my experience.
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