Wanted: Mash pH Measurements

[Silver_Is_Money]

One radical alternative that I'm starting to explore is to forego acidification of the mash altogether provided that the initial projection is for a mash at pH 5.8 or below, and also at pH 5.4 or above, and then subsequently adjust the post boil and cooling stage wort to a pH of 5.2. The post boil and cooling wort would be pH tested at 20 degrees C. (68 degrees F.) and then adjusted to pH 5.2 (also as measured at 20 degrees C.) based solely upon the input of OG and kettle volume at this late stage in the game. I have Alpha level software available for independent testing that attempts to achieve this. No guarantees of course. But this is drifting well away from the OP's intent for this thread....

 

[ScrewyBrewer]

I have Alpha level software available for independent testing that attempts to achieve this. No guarantees of course. But this is drifting well away from the OP's intent for this thread....

I think this concept is worthy of it's own thread as well.

 

[Robert65]

I think this concept is worthy of it's own thread as well.

+1

 

[dmr]

I'm still testing...
View attachment 644681

Hi Balrog. I noticed the above post of yours in another thread. I'd greatly appreciate it if you could add the data from this set of beers to this thread. (I note that you did this for your Boont Amber Ale.) Would that be possible? Cheers!

 

[balrog]

Hi Balrog. I noticed the above post of yours in another thread. I'd greatly appreciate it if you could add the data from this set of beers to this thread. (I note that you did this for your Boont Amber Ale.) Would that be possible? Cheers!

I am a neophyte at pH, and brewing as well, frankly. I've only done 150 batches and would not in any way say I have things dialed in. As to measuring pH, I am really scratching my head and wonder if I'm doing it wrong, or with a questionable meter because it really sometimes defies understanding. I do calibrate 7 & 4 every time, and measure wort sample at calibration temps.

Also, the pH measurements is different spreadsheet than recipe unfortunately, which makes creating a concise, collated reply interesting. Having said all that, and being somewhat lazy at recalculating anything en masse every time they alter their tools' version (I gave up after a while), I would be willing to share what I have and open myself up to constructive review and general internet ridicule. Are you still more interested in the dark recipes only or everything, dark and light?

 

[ScrewyBrewer]

@dmr the recipe below was originally brewed on my 15 gallon BIAB system and later scaled up and brewed on an 11 barrel system. The actual ph reading was 5.25 and the predicted mash pH value was 5.30.

I prepare my RO water the night before brewday. On brewday, before heating the strike water I add in salts, minerals, and acid as predicted by ezRecipe. Pulling a wort sample at 30 minutes into the mash and cooling it to ~77F before taking a pH reading.

The grain crush is 0.032 and I use untreated RO water for sparging. And record the mash pH readings whether they are as predicted or not. I don't make mash pH adjustments until brewing the same recipe again.

I hope this helps.

 

[dmr]

I am a neophyte at pH, and brewing as well, frankly. I've only done 150 batches and would not in any way say I have things dialed in. As to measuring pH, I am really scratching my head and wonder if I'm doing it wrong, or with a questionable meter because it really sometimes defies understanding. I do calibrate 7 & 4 every time, and measure wort sample at calibration temps.

Also, the pH measurements is different spreadsheet than recipe unfortunately, which makes creating a concise, collated reply interesting. Having said all that, and being somewhat lazy at recalculating anything en masse every time they alter their tools' version (I gave up after a while), I would be willing to share what I have and open myself up to constructive review and general internet ridicule. Are you still more interested in the dark recipes only or everything, dark and light?

As I replied in my message, I'd like to see data from any and all of your beers. Thanks!

 

[ScrewyBrewer]

@dmr this is a recipe I brewed last Sunday. It's my basic Pale Ale recipe brewed using whole hop flowers from Edwards Hop Farm located in New Jersey. The predicted mash pH was 5.40 and the actual mash pH measured at 67F was 5.27.

I prepared the RO brewing water on brewday morning while heating the strike water adding salts, minerals, and acid as predicted by ezRecipe. The wort sample was drawn 30 minutes into the mash and then cooled ~67F before taking a pH reading. Grain crush gap used is 0.032 and untreated RO water was used for sparging.

I hope my brewing results are helpful to you.

 

[dmr]

@dmr this is a recipe I brewed last Sunday. It's my basic Pale Ale recipe brewed using whole hop flowers from Edwards Hop Farm located in New Jersey. The predicted mash pH was 5.40 and the actual mash pH measured at 67F was 5.27.

View attachment 662033
View attachment 662034
View attachment 662035

I prepared the RO brewing water on brewday morning while heating the strike water adding salts, minerals, and acid as predicted by ezRecipe. The wort sample was drawn 30 minutes into the mash and then cooled ~67F before taking a pH reading. Grain crush gap used is 0.032 and untreated RO water was used for sparging.

View attachment 662036

I hope my brewing results are helpful to you.

Yes, they are quite helpful! Thanks!

 

[uprightfever]

9 lb Best Pilsen - 1.8L
1 lb Avangard Munich - 6L
1 lb flaked oats - 1L
14.75 qts RO water (I've tested my RO water with a salifert test for alkalinity and it changes color on the first drop, so there should be very little carbonate in it, I treat is as distilled and assume 0 for all ions when plugging in values.)
1.69 g CaSO4
1.34 g MgSO4
1.09 g CaCl
0.17 g NaCl
30 mL phosphoric - 10%
Mash pH 5.39 @ 20 min (didn't record the temperature, but I let it cool a bit before taking, maybe 100F?) My meter is supposed to correct for temperature, but I figure closer to room temp is likely more accurate.

I used the MpH V4.2 spreadsheet and targeted 5.40. Very happy with the MpH sheet compared to others I've tried.

 

[uprightfever]

16.5 lb Best Pilsen - 1.8L
21.6 qts RO water
0.92 g CaSO4
1.07 g CaCl
71 mL phosphoric - 10%
Mash pH 5.30 @ 20 min, 50.5 ºC

So, I've learned that I've been measuring pH incorrectly. I wouldn't use either this entry or the one above for anything.

 

[Silver_Is_Money]

I hope you didn't take the pH reading at 50.5 degrees C, as ATC does not correct for temperature the way you may be thinking it does. What ATC does assure you of is that the pH you read will be correct at the temperature you are reading it at, but what it does not do is automatically convert a high temperature pH reading into a low temperature pH reading (as most seem to believe that it does). For example, if you read 5.3 pH at 50.5 degrees C. that is correct. But if you read the same sample at 20 degrees C. and get 5.55 pH, that is also correct. The bottom line is that both are correct. But what is assuredly not correct is that 5.3 pH at 50.5 degrees C. is going to also read 5.3 pH at 20 degrees C. Things are inherently more acidic at higher temperatures.

 

[uprightfever]

I'm using an Apera SX620. I can't seem to find any documentation to confirm or refute what you've said. I have no reason to reject your claim though. The only thing I've found says "±0.01 pH accuracy; Automatic 3-point calibration; 0-60˚C Automatic Temp. Compensation," so I figured I was good. Thanks for the heads up.

Are there any concerns about letting the wort sit exposed to the atmosphere while it cools affecting the reading? Evaporation, oxygen or other gasses diffusing into solution?

I'll take measurements at elevated and room temp next time. Maybe I'll test it on some finished beer at a few temps. Fun little science experiment.

 

[uprightfever]

OK, I found this: BYO Principles of pH. It agrees with what you're saying. I'm pretty well on board with it.

So, that being said, the MpH spreadsheet prediction seems to be off then. Maybe Beersmith is closer (it wanted 100 mL vs 71 mL?) Perhaps my SOP is poor? I calibrated at 4/7/10 before my previous brew a couple weeks ago and stored the probe with storage solution, rinse with distilled before and after measurements.

 

[Silver_Is_Money]

Cool the sample rapidly on ice, or in your freezer. Use the smallest glass your probe will comfortably fit into for your sample, such that there is less sample requiring to be cooled. A shot glass often suffices here.

As for now, you had best 'initially' presume that your "room temperature adjusted" mash pH readings were ~0.2 pH points higher than what you have been reporting here.

Don't stir the sample with the probe, as that induces "stirring error" which is always a false low reading. And don't trust that the probe is reading the correct pH as soon as the stability indicator appears. Let it sit at least a minute beyond that juncture and then read it.

Taking the mash pH sample earlier than the 30 minute mark can also yield a false low pH reading.

 

[Silver_Is_Money]

Were you aware that Beersmith uses MpH code for it's pH math modeling? Version 3.0 as of now, I believe.

 

[Silver_Is_Money]

Quoting from the link I've provided (below the quote) for understanding ATC:

Will ATC adjust the measured sample pH result to the result expected at 25°C? Does it work like
conductivity temperature compensation?
No, ATC does not work like conductivity temperature compensation. We cannot adjust a measured sample pH value at one
temperature to an expected sample pH value at another temperature (e.g. 25°C), because we do not know how the pH of a
sample varies with temperature. For example, the pH value of a water sample may change rapidly as the result of chemical,
physical, or biological processes that are temperature dependent. If we want to know what the pH value of the sample is at
a certain temperature, we would have to adjust the sample to that temperature and measure the pH. That is why pH is
frequently reported with a temperature measurement. We understand that the pH of a sample is temperature dependent.
While ATC does allow us to calibrate accurately and adjust the pH electrode calibration when the temperature changes,
ATC can’t correct for sample pH/temperature effects, which are unknown.

https://assets.thermofisher.com/TFS...p-Compensation-pH-Measure-ST-ATCPHMEAS-EN.pdf

 

[Oginme]

Were you aware that Beersmith uses MpH code for it's pH math modeling? Version 3.0 as of now, I believe.

Brad has not released an update since Mark released his latest version, so it is still Mark's 3.0 version. Brad has said that he is working on BS3.1 which should be out soon, so hopefully he has updated to Mark's 4.2 version.

 

[VikeMan]

Brad has not released an update since Mark released his latest version, so it is still Mark's 3.0 version. He has said that he is working on BS3.1 which should be out soon, so hopefully he has updated to Mark's 4.2 version.

However, if anyone wants MpH version 4.2 as part of an integrated (and free) brewing solution, its models are in BrewCipher (as of BrewCipher Version 6). Just sayin'

 

[Silver_Is_Money]

For now it appears that we may conclude that (just as for all other mash pH assistant software, mine included) the new MpH 4.2 is not the panacea of software precision that @uprightfever rashly rushed forward to proclaim it to be, based upon merely a scant two samples, and a clear misunderstanding of pH meters with regard to temperature, and with what potentially appears to have been a heaping helping of confirmation bias.

 

[Oginme]

However, if anyone wants MpH version 4.2 as part of an integrated (and free) brewing solution, its models are in BrewCipher (as of BrewCipher Version 6). Just sayin'

If anyone wants Mark's v4.2, he offers it as a spreadsheet download from his blog site: Homebrewing Physics

Just dayin'

 

[VikeMan]

If anyone wants Mark's v4.2, he offers it as a spreadsheet download from his blog site: Homebrewing Physics

Just dayin'

Lol. That's quite true. I often recommend Mark's standalone sheet (and in fact have contributed fairly substantially to the measurements behind the model), but this recommendation was for the context of someone who was considering BeerSmith, and who already had the standalone MpH.

 

[ScrewyBrewer]

Don't stir the sample with the probe, as that induces "stirring error" which is always a false low reading. And don't trust that the probe is reading the correct pH as soon as the stability indicator appears. Let it sit at least a minute beyond that juncture and then read it.

I'm not sure how this message keeps getting misconstrued but stirring is definitely recommended during pH calibration and when taking pH measurements.

"A magnetic stirrer will ensure that the pH buffer or sample is completely mixed. The movement will also increase the response time of the electrode in the solution. If you don't use a magnetic stirrer, you should gently stir your sample with the probe while calibrating and testing."

https://blog.hannainst.com/ph-meter-calibration

 

[Silver_Is_Money]

I guess the case can clearly be made that some pH meters are designed to accomodate stirring, but this should not be misconstrued whereby to extend such advice to all pH meters.

pH readings are definitely seen to "fall" when under the influence of stirring. I can see where both calibration and reading must be subjected to the same quantitative degree or magnitude of stirring in order to have stirring error appear at the same magnitude for both, effectively negating it. This would allow for an exception.

 

[VikeMan]

In my opinion/understanding, the reason pH meters "fall" when stirring is that they are heading toward the same destination, only faster. I'll also say that a reading that has appeared to settle can drop further if suddenly stirred, but I believe time would have done the same thing. I own two Milwaukee meters, an M101 and an M102. One difference between them is that the M102 decides for you when the reading is stable. That's both the best and the worst thing about it.

Is there something in the literature anywhere about this "stirring error?"

 

[Silver_Is_Money]

In my opinion/understanding, the reason pH meters "fall" when stirring is that they are heading toward the same destination, only faster. I'll also say that a reading that has appeared to settle can drop further if suddenly stirred, but I believe time would have done the same thing. I own two Milwaukee meters, an M101 and an M102. One difference between them is that the M102 decides for you when the reading is stable. That's both the best and the worst thing about it.

Is there something in the literature anywhere about this "stirring error?"

My meter always falls when stirred, and never settles out at such a low reading afterward, always rising during settling

AJ deLange spoke at least several times in regard to "stirring error" and the critical need to avoid it. I have not researched it beyond reading some of his comments on the phenomenon. He suggested that it could be intentionally used as means whereby to achieve confirmation bias, as in driving a pH down such that it matches a preconceived target pH.

 

[Silver_Is_Money]

This link points to some of the instances wherein AJ deLange has discussed "stirring error":

https://www.homebrewtalk.com/search/7510/?q="stirring+error"&c[users]=ajdelange&o=relevance

 

[mabrungard]

I do see some movement in pH if I stir the sample, but it tends to return to an equilibrium value once the sample and probe have achieved a terminal state. I still find that stirring prior to that terminal state, does speed the equilibrium.

Do stir initially, but let the sample sit to determine the final pH.

 

[VikeMan]

Interesting. I note that AJ had this to say in one of his posts:

"Stirring error should disappear as soon as you stop stirring i.e. if the pH has dropped 0.08 pH when you started stirring it should go back up by about 0.08 pH pretty quickly. "

Which is consistent with what @mabrungard said above.

 

[dmr]

For now it appears that we may conclude that (just as for all other mash pH assistant software, mine included) the new MpH 4.2 is not the panacea of software precision that @uprightfever rashly rushed forward to proclaim it to be, based upon merely a scant two samples, and a clear misunderstanding of pH meters with regard to temperature, and with what potentially appears to have been a heaping helping of confirmation bias.

I don't think mash pH software will ever be a panacea. It can, however, be quite helpful in estimating mash pH. How good of an estimate? Based on data I have collected from homebrewers that have shared their data with me (and a few data sets I have gleaned from the interweb), I have compared a number of calculators that are out there. As an example, the Brewer's Friend calculator appears to be one of the better calculators. For the 35 data sets that I have run through it, its performance can be characterized as follows: On average its prediction is 0.05 high with a standard deviation of 0.13. Given this (and without getting all crazy with statistical analysis), I'd estimate that a good piece of software will get you to within +- 0.2 most of the time. Indeed, out of those 35 data sets only 5 measurements had deviations with magnitude > 0.2 from the Brewer's Friend prediction.

In my mind the biggest issue with mash prediction is the variability in distilled-water pH of base grains. These seem to vary quite a bit from batch to batch, largely due to the amount of lactobacillus bacteria that comes along for the ride. (This has been documented in the literature, although -- off the top of my head -- I don't recall the reference).

Cheers!