Author Topic: Mash pH temperature correction?  (Read 1082 times)

Offline Shawn3997

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Mash pH temperature correction?
« on: April 28, 2018, 01:21:56 AM »
If my mash pH is 5.65 at room temperature and is thus corrected to a 5.3 pH at mash temperatures, does that mean my mash pH is 5.3 and therefore doesn't need correcting?  I'm doing an all Pilsner beer and not using any acid correction.  Am I fine?

Offline Steve L

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Re: Mash pH temperature correction?
« Reply #1 on: April 28, 2018, 02:16:54 AM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. having said that, 5.6 isn't the end of the world. You should be fine.
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Offline Robert

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Re: Mash pH temperature correction?
« Reply #2 on: April 28, 2018, 02:43:50 AM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.
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Offline Shawn3997

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Re: Mash pH temperature correction?
« Reply #3 on: April 28, 2018, 02:55:33 AM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.

So when one says you should have a mash pH of 5.2, for instance, they mean if you measure the mash at mash temperature you would get a 5.55 (with the 0.35 correction)?

Offline Robert

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Re: Mash pH temperature correction?
« Reply #4 on: April 28, 2018, 03:04:23 AM »
The "0.35 correction" is really something of a homebrew myth, actually.  pH will always measure lower at mash temp than the actual room temp pH, but there is no correction formula.  The displacement is unique to each mash, depending on grist, water composition, time, temperature and other factors, and varies widely (from around 0.1 to 0.6.)  The only way to know the mash pH is to measure it at room temperature.
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Offline tommymorris

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Mash pH temperature correction?
« Reply #5 on: April 28, 2018, 04:32:38 AM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.
Does this mean the pH value predicted by Brunwater is for 20C rather than 25C (room temperature)?

Offline Robert

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Re: Mash pH temperature correction?
« Reply #6 on: April 28, 2018, 11:22:58 AM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.
Does this mean the pH value predicted by Brunwater is for 20C rather than 25C (room temperature)?
I don't know, what does Bru'n Water say? Anyway, there is a negligible difference between 20° and 25°C (or lower) as far as I know.  (Temperature in whose room anyway? Mine's pretty chilly this morning.)  It's as the temperature rises higher the displacement gets bigger.
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Offline Steve L

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Re: Mash pH temperature correction?
« Reply #7 on: April 28, 2018, 12:29:24 PM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.
Yes you are correct, one of those posts where you throw in the "almost" as a matter of habit, but yes, always at room temp. I use medicine cups for samples during mashing. they cool quickly and are the right size for my probe.

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Re: Mash pH temperature correction?
« Reply #8 on: April 28, 2018, 12:30:21 PM »
When referencing Mash PH, it's almost always at room temperature that you should target and measure. 
Not almost always.  Always.  pH always refers to pH measured under standard reference conditions,  or it is meaningless.  In brewing that has always meant 20°C, and remember that if your meter has ATC,  that only corrects for the function of the electrode, not the actual change in mash chemistry at different temperatures. You must still measure pH at room temperature.

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Re: Mash pH temperature correction?
« Reply #9 on: April 28, 2018, 01:14:36 PM »
Always record your mash pH at room temperature, which for the OP is 5.65.  That is indeed a bit high.  I'll bet the beer still turns out fine, but ideally should be adjusted down by salts or acid.

The correction between mash temp and room temp is 0.25, not 0.35.  This has been confirmed by several including myself.  I have measured mash pH at mash temp without ill effect, aiming for 5.4 at room temp and 5.15 at mash temp if measured there.
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Offline Big Monk

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Re: Mash pH temperature correction?
« Reply #10 on: April 28, 2018, 07:42:53 PM »
Always record your mash pH at room temperature, which for the OP is 5.65.  That is indeed a bit high.  I'll bet the beer still turns out fine, but ideally should be adjusted down by salts or acid.

The correction between mash temp and room temp is 0.25, not 0.35.  This has been confirmed by several including myself.  I have measured mash pH at mash temp without ill effect, aiming for 5.4 at room temp and 5.15 at mash temp if measured there.

Unless you specify the mash temp there is no such thing as a universal correction factor.
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Re: Mash pH temperature correction?
« Reply #11 on: April 28, 2018, 07:49:24 PM »
Always record your mash pH at room temperature, which for the OP is 5.65.  That is indeed a bit high.  I'll bet the beer still turns out fine, but ideally should be adjusted down by salts or acid.

The correction between mash temp and room temp is 0.25, not 0.35.  This has been confirmed by several including myself.  I have measured mash pH at mash temp without ill effect, aiming for 5.4 at room temp and 5.15 at mash temp if measured there.

Unless you specify the mash temp there is no such thing as a universal correction factor.

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Offline Big Monk

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Re: Mash pH temperature correction?
« Reply #12 on: April 28, 2018, 08:28:39 PM »
Always record your mash pH at room temperature, which for the OP is 5.65.  That is indeed a bit high.  I'll bet the beer still turns out fine, but ideally should be adjusted down by salts or acid.

The correction between mash temp and room temp is 0.25, not 0.35.  This has been confirmed by several including myself.  I have measured mash pH at mash temp without ill effect, aiming for 5.4 at room temp and 5.15 at mash temp if measured there.

Unless you specify the mash temp there is no such thing as a universal correction factor.

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Re: Mash pH temperature correction?
« Reply #13 on: April 28, 2018, 09:22:31 PM »
For those who mash single infusion about 150 F, see my response above.  For those who step mash at 7 different temperatures, I don't know what the pH is at different temps.
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Offline Robert

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Re: Mash pH temperature correction?
« Reply #14 on: April 28, 2018, 09:31:04 PM »
Always record your mash pH at room temperature, which for the OP is 5.65.  That is indeed a bit high.  I'll bet the beer still turns out fine, but ideally should be adjusted down by salts or acid.

The correction between mash temp and room temp is 0.25, not 0.35.  This has been confirmed by several including myself.  I have measured mash pH at mash temp without ill effect, aiming for 5.4 at room temp and 5.15 at mash temp if measured there.

Unless you specify the mash temp there is no such thing as a universal correction factor.
There is no universal correction factor even with specified temperature, because the composition of each mash makes it behave in its own way, it seems. Published experiments bear this out; just for starters see DeClerck ch. XII.  Palmer and Kaminski promulgated a supposed correction formula that involved multiplying the difference between mash temperature and reference temperature by a constant and adding this to the apparent pH. I tried it countless times and found it was always wrong, usually by a significant margin,  and in no consistent way.   If someone seems to regularly see the same "correction," say 0.35, 0.25, etc, I would suspect this is because they are regularly setting up similar conditions --  liquor, grist, procedures, what have you.  I would not want to suggest to a brewer that they can trust anyone else's results;  best to take an accurate measurement yourself under the correct conditions. Should you find you can establish your own rule of thumb, that's fine.
Rob Stein
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