Author Topic: Boil ph...  (Read 1972 times)

Offline PORTERHAUS

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Boil ph...
« on: December 02, 2015, 09:31:11 PM »
I have done some searches as I always do before posting a new topic and didnt find anything directly related to what im looking for. This is a very experienced forum and I like the science in brewing so there is something I wanted to clarify as I am taking my brewing more and more serious as of lately. I know there is a lot of talk going on lately about mash ph and I feel I understand that well. I even learned of some things I want to try with my dark beers (shooting for a higher mash ph). But when it comes to boil ph lets discuss some things:

1) What is the ideal boil ph? Should it be about the same as your mash?

2) How do we reference that boil ph? Of course we would be working with a cooled room temp sample but do we take in effect the .3-.35 higher reading for a cooled sample like we do with checking mash ph? Or even more since at boiling the temperature difference is greater?

3) What about post boil ph? And again how do we reference that? I know we should work with a cooled sample but do we take the reading we have for the cooled wort or should we factor it like mash ph where there is a difference in the ph for the actual temp it will be at in that process?

On a side note I always wondered the same for acidifying the sparge. We know we shouldnt go above 6.0 with are sparge ph but again is that dealing with the temp it will actually be at for the sparge?...so treat that like mash ph as well?

Im just trying to make sure I have my head wrapped around this correctly. Thanks all.

Offline mchrispen

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Re: Boil ph...
« Reply #1 on: December 02, 2015, 10:01:14 PM »
I'll take a swing at this:

I am going to reference Room Temperature, which should be somewhere between 68F and 73F (different ranges in different books), but a consistent target. This is important as you are looking for a reference point for the readings to make sense. If you read at mash temp, then you need to declare what that temperature is - and it changes dramatically batch to batch if you brew a lot of different beer styles.

Fortunately, you only need a small amount of wort to sample, so cooling to a specific temperature is easy in a set of nested steel bowls or a ice water bath and a shaker glass. Literally takes me a few minutes max to take a stable pH reading, even of boiling wort.

1) It varies... much like many of us like to vary mash pH to affect the malt flavors. That said - 5.2-5.0 is the ideal range for break formation. If you believe that an aggressive boil and break precipitation is a mark of good practice, then acidifying the boil can help. The result should be very clear wort into the fermenter. Also keep in mind that boil pH affects hop utilization - so lower pH may have a softer less intense hop utilization, where a higher pH may yield a rougher and more brash hop character. The boil will naturally drop 0.2-0.3 pH units in the boil - so if your mash pH is at a nominal 5.4, then you will naturally see the pH drop into that 5.1 range over time, unless your sparge water is overly alkaline. So experiment on a recipe basis.

2) The cooled sample to room temperature is important. All mash pH and other brewery pH references should be at the same general temperature. It will naturally be lower at boil temperatures... further even than mash pH as the delta is another 60-70F. Room temperature provides a consistent reference point. Better if you can hit specific temps consistently.

3) Post boil pH can be useful to determine yeast activity before krausen shows. The readings should be at room temperature as well. Finish beer pH will, of course, vary by yeast strain. You have seen some of the discussions of final adjustments which can add some more control if you wish to use it.

Acidifying sparge is interesting, as there are two possible goals. The primary should be to remove alkalinity in the water to reduce tannin extraction during lauter. It is also a way of adding acid to the boil as the excess H+ will follow into the boil and have a more immediate effect in the kettle. I have played with acidifying my RO to my mash pH target and had mixed results... so have come back to making a kettle adjustment if I do NOT see good break material after 30 minutes into the boil.

Offline PORTERHAUS

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Re: Boil ph...
« Reply #2 on: December 03, 2015, 10:58:20 AM »
First thanks for the response I appreciate it. I understand and am familiar with most of what you posted, the real confusion is from when I see actual mash ph and ph from a cooled sample exchanged in the same sense. I understand a cooled mash sample will read about .3 ph higher. So if we aim for an ACTUAL ph of say 5.3 the ACTUAL ph my meter will indicate with a cooled room temp sample will be .3 higher or so and will read something like 5.6. Ok, I'm good with that. My question is and I belive you did answer that is do we deal with the Pre and Post boil and even sparge ph in that same sense?

Offline mchrispen

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Re: Boil ph...
« Reply #3 on: December 03, 2015, 12:30:25 PM »
Yes, I treat all the same relative to room temp.

You have to be careful with some texts that do not reference the pH temperature, so dig a bit deeper to find out the reference point. Most homebrew references are now at room temps, so a 5.3 target (at which temp?) at mash temps would see on the high end of the spectrum to me, reading 5.6 at room temp.

Offline PORTERHAUS

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Re: Boil ph...
« Reply #4 on: December 06, 2015, 05:57:48 AM »
Based on what you replied above and talks in another thread. I think I have come to realize I have been confusing myself all this time with mash ph. I always compesated by adding .3 onto my target mash ph because thats what it would be at room temp. Not realizing "the target ranges" often indicated were for cooled samples... it seems I have been running my mash ph's too high.  :-\

Offline klickitat jim

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Re: Boil ph...
« Reply #5 on: December 06, 2015, 06:42:46 AM »
Based on what you replied above and talks in another thread. I think I have come to realize I have been confusing myself all this time with mash ph. I always compesated by adding .3 onto my target mash ph because thats what it would be at room temp. Not realizing "the target ranges" often indicated were for cooled samples... it seems I have been running my mash ph's too high.  :-\
Yes, see other thread. Numbers should always be for room temp tedtable sample.

Offline PORTERHAUS

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Re: Boil ph...
« Reply #6 on: December 06, 2015, 11:22:50 PM »
I seen that Jim, thanks. It all makes a bit more sense now.

Offline heavydeadlifts

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Re: Boil ph...
« Reply #7 on: December 07, 2015, 08:34:15 AM »
Wait, so if I'm using my Milwaukee 102 the temperature probe isn't automatically compensating my ph reading to what it would be at room temp?
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Offline klickitat jim

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Re: Boil ph...
« Reply #8 on: December 07, 2015, 09:12:18 AM »
Wait, so if I'm using my Milwaukee 102 the temperature probe isn't automatically compensating my ph reading to what it would be at room temp?
Here ya go. But its possible there should be a comma after the first word...

Offline heavydeadlifts

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Re: Boil ph...
« Reply #9 on: December 07, 2015, 09:40:07 AM »
Actually I just read the manual/specs and it does automatically adjust the ph for temp up to 158f
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Offline JT

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Re: Boil ph...
« Reply #10 on: December 07, 2015, 03:09:17 PM »
Actually I just read the manual/specs and it does automatically adjust the ph for temp up to 158f
This is easy enough to test that you should do it.  I don't stick my meter in the uncooled mash after reading about the negative impact it has on the life of the probe. 

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Offline narvin

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Re: Boil ph...
« Reply #11 on: December 07, 2015, 05:30:14 PM »
Wait, so if I'm using my Milwaukee 102 the temperature probe isn't automatically compensating my ph reading to what it would be at room temp?

No, it's only correcting for error in electrical response of the probe at temperatures other than the reference temperature.  This ensures that the reading is accurate at any temperature.  It does not correct for the fact the pH actually changes as temperature changes due to increased H+ ion dissociation.. 
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Offline hopfenundmalz

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Re: Boil ph...
« Reply #12 on: December 07, 2015, 05:34:55 PM »
Wait, so if I'm using my Milwaukee 102 the temperature probe isn't automatically compensating my ph reading to what it would be at room temp?

No, it's only correcting for error in electrical response of the probe at temperatures other than the reference temperature.  This ensures that the reading is accurate at any temperature.  It does not correct for the fact the pH actually changes as temperature changes due to increased H+ ion dissociation..
This^^^^.

So everyone thinks that pH for wort will follow the same temperature dependent curve as for other solutions? I don't think so, but I am not a chemist.

We have pH meters, these measure pH for any solution, not just wort.
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Offline mchrispen

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Re: Boil ph...
« Reply #13 on: December 07, 2015, 06:09:49 PM »
Quote
No, it's only correcting for error in electrical response of the probe at temperatures other than the reference temperature.  This ensures that the reading is accurate at any temperature.  It does not correct for the fact the pH actually changes as temperature changes due to increased H+ ion dissociation.. 

+100

Offline factory

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Re: Boil ph...
« Reply #14 on: December 07, 2015, 07:09:22 PM »
Quote
No, it's only correcting for error in electrical response of the probe at temperatures other than the reference temperature.  This ensures that the reading is accurate at any temperature.  It does not correct for the fact the pH actually changes as temperature changes due to increased H+ ion dissociation.. 

+100

OK, pardon my confusion with this topic.  I have the Milwaukee 102.  Say I have a sample that measures pH at 5.6 and the sample is at 90F.  Is that the same as it would be at 68f? (due to the temperature correction feature?)