75 replies to this topic

[Big Nake]

We touched on this once before but I need to clarify this.  I have seen people write about using their pH meter at mash temp, room temp, etc. and saying that their pH was 5.6 at mash temp and 5.3 at room or whatever.  I usually take a sample of my mash and put it into a frozen glass to get the temp of the sample lower quicker.  At some point I will place my meter in there and watch the reading as the temp is maybe at 90°, then 75°, etc.  I leave the meter in there the whole time and watch the pH.  If it settles at 5.6 or 5.8 or whatever, I'll use a little acid in the mash and recheck the pH a few minutes later.  But if my meter (a Milwaukee PH55 with ATC) says that my pH is 5.3 or 5.4 or whatever, that's the pH, correct?  If it says 5.4 at 90° and 5.4 at 65°, am I supposed to be adjusting somehow or is my pH 5.4?  I thought the only adjustment needed was if you were using strips and if you had an ATC meter, it was automatically adjusting the pH based on the temp (automatic temp correction?  Automatic temp compensation?).  Am I missing something here?

[positiveContact]

real life pH changes with temperature.  i'm not sure what your meter is doing.

 

the thing that i never got was why don't people spec the pH at mash temp so everyone can avoid this silly cooling a sample step.

Edited by TheGuv, 18 November 2013 - 05:33 PM.

[MtnBrewer]

Ken this came up in a thread a week or two ago. ATC and the offset between room temp and mash temp are two different things. ATC corrects for errors in the instrument itself due to temperature. The pH change at different temperatures is a real change in pH so your meter should show a different reading at different temperatures. Why can't it compensate for this you say? Because it doesn't know that you're measuring wort, which just happens to have about a 0.3 pH difference. Different substances would have a different pH change. For example, pure de-ionized water would read pH 7.0 at any temperature.

[MtnBrewer]

the thing that i never got was why don't people spec the pH at mash temp so everyone can avoid this silly cooling a sample step.

The reason is that most people don't have a meter that will read at those temps. And even if they did, higher temps seriously degrade probe life so it's not recommended even if your meter is capable.

[positiveContact]

The reason is that most people don't have a meter that will read at those temps. And even if they did, higher temps seriously degrade probe life so it's not recommended even if your meter is capable.

 

things i might know if i owned a probe

 

glad my colorphast strips work just fine at mash temps

[MtnBrewer]

things i might know if i owned a probe  glad my colorphast strips work just fine at mash temps

A new probe is only slightly more expensive than a box of strips.

[JMcG]

Room temp is the standard lab condition.  The pH meter with ATC reports the actual pH measured at the temperature tested, but the pH changes as the temperature changes, so to have "standardized conditions" the pH in the literature is reported at room temperature (STP: Standard Temperature and Pressure).

So, you have to correct for the temperature reading if you test at mash temp.

[Brauer]

But if my meter (a Milwaukee PH55 with ATC) says that my pH is 5.3 or 5.4 or whatever, that's the pH, correct?  If it says 5.4 at 90° and 5.4 at 65°, am I supposed to be adjusting somehow or is my pH 5.4?

pH of a mash drops somewhere between 0.25-0.35 pH from room temperature to mash temperature.  pH is, as JMcG says, assumed to be measured at room temp so that we can talk about pH without always having to follow it up with "at X°F).

 

You might want a mash pH 5.4, which is the room temperature pH.  If you hit that pH, then raise the temperature to 95°F, it will measure at about pH 5.3.  If you raise it to 125°F, it will measure about pH 5.2. That is mostly because of the chemistry of water.   Your mash pH is still 5.4, since that is defined as the pH at mash temperature.

 

Those are estimates, based on an assumption that the pH drops ~0.3 from 65-150°F, which might not be entirely accurate but it is probably close.

[Steve Urquell]

I measure mash pH at the same temp I calibrated my meter at. Room temp. I shoot for a mash temp of 5.3-5.5 which is what all the water gurus recommend and that has given me good results on light lagers to 12-15 SRM ales--I shoot for 5.3 on the lagers.

 

Also, as Mtn said, high temps degrade probe life as well.

[positiveContact]

A new probe is only slightly more expensive than a box of strips.

 

while an interesting fact it's kind of meaningless without knowing how many uses you get out of it.  i get 200 uses (by cutting strips in half) out of my about $30 box.

[Big Nake]

My meter does fluctuate slightly but if I place my meter in a 90° mash sample and it goes to about 5.4 (for example) and then I leave it while the temp drops to 70° or so, it's usually still reading the same so I guess I thought the ATC was just keeping things consistent for convenience purposes.  So if I placed my meter in 125° wort (which I wouldn't) and it said 5.2, I should expect to see the pH rise a little bit as the sample cools, correct?  Bottom line is that when we say 5.2 to 5.6 as the ideal range (or whatever you consider the ideal range to be), that should be measured at room temp so we're all on the same page.  Do I have this right?

 

Chils... I agree that on some of my more pale beers, I shoot for a slightly lower mash pH to bring that snap to the beer.  That could be true for lagers or ales... blonde ales, wheats, etc. 

[positiveContact]

My meter does fluctuate slightly but if I place my meter in a 90° mash sample and it goes to about 5.4 (for example) and then I leave it while the temp drops to 70° or so, it's usually still reading the same so I guess I thought the ATC was just keeping things consistent for convenience purposes.  So if I placed my meter in 125° wort (which I wouldn't) and it said 5.2, I should expect to see the pH rise a little bit as the sample cools, correct?  Bottom line is that when we say 5.2 to 5.6 as the ideal range (or whatever you consider the ideal range to be), that should be measured at room temp so we're all on the same page.  Do I have this right?

 

Chils... I agree that on some of my more pale beers, I shoot for a slightly lower mash pH to bring that snap to the beer.  That could be true for lagers or ales... blonde ales, wheats, etc. 

 

you are correct.  measure at room temp ken.

 

the only reason i can measure at mash temps is a happy accident with the colorphast strips.

[Brauer]

My meter does fluctuate slightly but if I place my meter in a 90° mash sample and it goes to about 5.4 (for example) and then I leave it while the temp drops to 70° or so, it's usually still reading the same so I guess I thought the ATC was just keeping things consistent for convenience purposes. 

Do you have one that only reads to 1 decimal place?  In that case, the pH could drop from 5.44 to 5.35, and still read 5.4.

[Big Nake]

Do you have one that only reads to 1 decimal place?  In that case, the pH could drop from 5.44 to 5.35, and still read 5.4.

Yes.  I should have mentioned that.  The display actually does go to two places past the decimal because when I calibrate it, it shows "4.01 or 7.01" or whatever.  But in normal USE mode, it's 5.2, 5.3, 5.4, etc.  So I think you're right, it could be fluctuating inside of a 1 point range without changing the display.  I just want to make sure that when the meter is sitting in a 60-70° sample and shows a pH, that's it and I don't have to worry about the temp, the pH, adjusting anything, etc.  Thanks brewing brothers.

[MtnBrewer]

Bottom line is that when we say 5.2 to 5.6 as the ideal range (or whatever you consider the ideal range to be), that should be measured at room temp so we're all on the same page.  Do I have this right?

Next question: so what is the optimal pH of the mash or is there even an optimum?

[denny]

From the Bru'nwater water knowledge page....the best place to look for questions like this...

 

"[font="Arial, sans-serif;"]The pH of the mash influences a number of factors in brewing including; fermentability, color, clarity, and taste of the wort and beer.  [/font]A slightly acidic mash pH of between 5.2 and 5.8 (measured at room-temperature) improves the enzymatic processes during mashing.  The lower end of that range produces more fermentable wort and thinner body.  The lower end of that range also produces better extraction efficiency, lighter color, better hot break formation, and the beer is less prone to form haze.  Allowing the mash pH to fall below this lower boundary increases the potential to solubilize excess protein into the wort (De Clerck, 1957).  The upper end of that range produces less fermentable wort and more body (Briggs et. al., 1981).  Tailoring the mash pH helps a brewer create the wort character desired for the finished beer.  In most cases, narrowing the target mash pH range to between 5.3 and 5.5 is recommended. "

Edited by denny, 19 November 2013 - 10:24 AM.

[Big Nake]

That part in bold resonates with me.  As I have been focusing very closely on mash pH (and preboil wort pH), I have found that a number of beers coming to the taps where the mash pH was lower (5.2 to 5.4 or 5.5) are clearer, cleaner-tasting and just tastier to me.  The fact that the beer would be thinner and more fermentable suggests that lower mash pH almost shadows mash temperature.  All of this goes back to a conversation we once had about "flabby" beers and what that actually meant.  I think many people thought that a flabby beer means that it was mashed with a high pH and didn't have a crispness to it that you might want in a beer.  This is all personal preference but it sounds like a lower mash pH is going to have a slightly more acidic & snappy flavor to it than a beer mashed with a higher pH.  Very interesting stuff and some nice fine-tuning tools for our collective toolbox.

[positiveContact]

i'll be adding a shit ton of gypsum to my  next couple of ipas.  it's going to be legen... wait for it... dary!

[denny]

i'll be adding a shit ton of gypsum to my  next couple of ipas.  it's going to be legen... wait for it... dary!

 

I recommend shooting for 300 ppm.

[MtnBrewer]

I recommend shooting for 300 ppm.

Of sulfate right?