PH drops from 5.68 to 5.14 after mash! How could it happen?

[Miles_1111]

I brewed a stout last weekend and targeted on 5.6 mash PH. The actual mash PH was 5.68 (18.1 °C) which was a bit higher but I think it was OK. However, after mash and sparge the PH became 5.14 (21.9 °C) before boil, then got down to 4.81 (19.1 °C) after boil.

According to John's How to Brew, at room temperature before and after mash the PH should drop about 0.2 ( mine was 0.54! ) and before and after boil should drop 0.3 ( mine was 0.33 which is OK ). Any idea what caused the dramatic drop of PH during mash? My water treatment is below (ppm):

CAL: 73
Mg: 21
Na: 82
Sul: 58
Cl: 102
HCO3: 195

Thanks in advance for any comment.

 

[Qhrumphf]

I'm guessing your mash sample was collected/read prematurely and all the reactions to form it's pH weren't stable.

 

[Miles_1111]

I'm guessing your mash sample was collected/read prematurely and all the reactions to form it's pH weren't stable.

Can you please be more specific? Does it mean I collected the sample too early during mash? I think I did it around 5 mins after mix malt and water. Or I should wait longer time for the PH reader to read the wort? I tried a couple of time shaking the reader in the wort and it both went back to the data I read.

 

[Yooper]

It takes about 20 minutes for the mash pH to stabilize since you have to mix it well and allow it to equalize.

 

[Silver_Is_Money]

What are the full details of the components that made up the grist, and what volume of your water (as seen above) was it mashed within?

Also, what was the volume of sparge water, and what are the analyticals for your sparge water?

 

[Qhrumphf]

Can you please be more specific? Does it mean I collected the sample too early during mash? I think I did it around 5 mins after mix malt and water. Or I should wait longer time for the PH reader to read the wort? I tried a couple of time shaking the reader in the wort and it both went back to the data I read.

Reading after only 5 minutes is definitely premature. 20-30mins as Yooper said will get you a more accurate reading.

Stirring is also a factor. If your mash wasn't well mixed and pretty homogenous, and you pulled a section heavy on strike water compared to the rest of the mash, that'd also do it.

 

[marc1]

Were you measuring pH with a calibrated meter?

 

[Bilsch]

Were all the samples at the same room temperature while taking the pH reading?

 

[Miles_1111]

Reading after only 5 minutes is definitely premature. 20-30mins as Yooper said will get you a more accurate reading.

Stirring is also a factor. If your mash wasn't well mixed and pretty homogenous, and you pulled a section heavy on strike water compared to the rest of the mash, that'd also do it.

Just wondering sometimes the conversion is done in around 20-30mins. If the sample is taken by then ,will it be accurate?

If assuming the readings are right, is there any reason possibly caused the hugh drop of PH during mash?

 

[Miles_1111]

Were all the samples at the same room temperature while taking the pH reading?

All are room temperature, but there are around +-2 °C differences of 20 °C. I have marked the wort temperatures in the post. Will these differences a problem?

 

[Miles_1111]

Were you measuring pH with a calibrated meter?

It is a new bought meter and the seller said it was calibrated already so I did not do. Will get it done. But even if it is not correct, the hugh drop still exists..

 

[Bilsch]

All are room temperature, but there are around +-2 °C differences of 20 °C. I have marked the wort temperatures in the post. Will these differences a problem?

No your good there.
I'm betting on what Yooper said, you took the initial sample too soon.
Did you get the expected extract or were you way lower on the OG then predicted?

 

[Miles_1111]

What are the full details of the components that made up the grist, and what volume of your water (as seen above) was it mashed within?

Also, what was the volume of sparge water, and what are the analyticals for your sparge water?

The grain bill is:
Maris Ott 80%
Black roasted barley 6.7%
Special B 5.3%
Caramunich 2.7%
Chocolate Malt 2.7%
Pale Chocolate malt 2.7%

Because I do 10L batch, mash water was 14.6L (collected 8.8L) and sparge water was 4.3L. Finally got around 13L wort and after boil is 10L which put into fermenter.

For sparge water I just adddd 0.6g of CaCl2 and 1.5g MgSO4, did not add any NaHCO3 and CaCO3 which I also put in mash water. I got these after calculate in an excel called Brun water or something.

 

[Miles_1111]

No your good there.
I'm betting on what Yooper said, you took the initial sample too soon.
Did you get the expected extract or were you way lower on the OG then predicted?

Not at all, the efficiency is 10% lower than I ususaly do, because I used a new bought curled two-row grinder this time instead of a pan grinder I used before. That is another probelm which I should fix by narrow the gap next time. I have already noticed. The sample should be taken at the start of the conversion or in the middle or at finish?

 

[Bilsch]

Not at all, the efficiency is 10% lower than I ususaly do, because I used a new bought curled two-row grinder this time instead of a pan grinder I used before. That is another probelm which I should fix by narrow the gap next time. I have already noticed. The sample should be taken at the start of the conversion or in the middle or at finish?

I ask because low mash pH will effect the enzymes and lower your expected gravity. This could be a clue that your mash pH was actually lower then you thought. When to take your first reading depends on if you have a static (non-circulated) mash and or how well you stirred before taking that first pH reading. If the mash is agitated well, then 10 minutes in is ok, if more sedentary then 15-20 minutes before everything is stabilized.

 

[Qhrumphf]

It is a new bought meter and the seller said it was calibrated already so I did not do. Will get it done. But even if it is not correct, the hugh drop still exists..

pH meter rule #1, calibrate every day that it's used at minimum. If it's at all suspect, more often than that.

The catch 22 of mash pH is that by the time you can get an accurate mash pH measurement it's basically too late to do anything about it. Basically just data to make adjustments for next time. Not good for the homebrewer who always brews something different.

If you were to steep roasted malts late (say, add just before vorlauf) as many like to do (see: Gordon Strong) I could see that dropping wort pH well below mash pH. But I don't see that to be the case here.

 

[Miles_1111]

I ask because low mash pH will effect the enzymes and lower your expected gravity. This could be a clue that your mash pH was actually lower then you thought. When to take your first reading depends on if you have a static (non-circulated) mash and or how well you stirred before taking that first pH reading. If the mash is agitated well, then 10 minutes in is ok, if more sedentary then 15-20 minutes before everything is stabilized.

Got it. Mine is static mash. Taking sample at 5 mins is way to early... Thx~

 

[Miles_1111]

pH meter rule #1, calibrate every day that it's used at minimum. If it's at all suspect, more often than that.

The catch 22 of mash pH is that by the time you can get an accurate mash pH measurement it's basically too late to do anything about it. Basically just data to make adjustments for next time. Not good for the homebrewer who always brews something different.

If you were to steep roasted malts late (say, add just before vorlauf) as many like to do (see: Gordon Strong) I could see that dropping wort pH well below mash pH. But I don't see that to be the case here.

Yeah, not the case. I mash all the special malt including black roasted with basic malts together from the beginning. It seems the wrong reading at the beginning due to taking sample too early. I will pay attention and calibrate the meter before every brew. Thank you.

 

[Silver_Is_Money]

I ran your recipe (presuming 3 Kg. of grist) through the Metric version of 'Mash Made Easy' 9.60. For Crisp Maris Otter it predicted a mash pH of 5.58, and for Muntons Maris Otter it predicted a mash pH of 5.68, so I'm in good agreement with your assessed target of 5.6 pH for the mash.

Given 14.6L of mash water with a whopping ~160 ppm Alkalinity (as CaCO3) I can't imagine where sufficient grist acidity materialized whereby to mash at 5.14 pH. Nor can I imagine hitting 4.81 pH post boil. I can speculate that your pH meter went wonky on you at some juncture following your initial mash pH reading. Or alternately I can speculate that you forgot to add NaHCO3 and CaCO3 to your mash water, and thereby it had no Alkalinity. Or I can speculate that (since CaCO3 is quite highly insoluble in water, and thereby does not contribute nearly the calcium or alkalinity predicted for it by software) that this may have played some part.

Note: Most of us have completely abandoned the use of CaCO3 due to its serious insolubility issue. I believe Kai Troester (Braukaiser) ran a series tests wherein it only delivered at best about half of its software projected alkalinity and calcium content.

 

[Silver_Is_Money]

Technically, to go from pH 5.68 to pH 5.14 requires that ~3.47X more H+ ions (protons, or acid) be present. pH is the log base 10 measure of the molar concentration of free H+ ions.

10^−5.14÷10^−5.68 = 3.4674

 

[ScrewyBrewer]

I find sampling the mash for pH at twenty minutes in to be the sweet spot. That and cooling the sample to room temperature before taking a reading adds consistency to the process.

 

[Dancy]

I find sampling the mash for pH at twenty minutes in to be the sweet spot. That and cooling the sample to room temperature before taking a reading adds consistency to the process.

So if you take a sample at 20 minutes AND wait for it to cool, isn’t it way too late to do anything substantive to adjust the mash pH?

 

[VikeMan]

So if you take a sample at 20 minutes AND wait for it to cool, isn’t it way too late to do anything substantive to adjust the mash pH?

It is. But it will help dial in future batches.

 

[mabrungard]

The 20 minute mark is still too early and pH has not stabilized. While it’s okay to measure that early, I found that pH is fairly stable after the 45 minute mark.

Absolutely DO NOT chase pH during a mash. Use software or experience to properly plan the water amendments and then monitor how they turn out. As I pointed out above, you can’t tell how the pH will end up from an early measurement. Don’t try.

 

[Miles_1111]

I ran your recipe (presuming 3 Kg. of grist) through the Metric version of 'Mash Made Easy' 9.60. For Crisp Maris Otter it predicted a mash pH of 5.58, and for Muntons Maris Otter it predicted a mash pH of 5.68, so I'm in good agreement with your assessed target of 5.6 pH for the mash.

Given 14.6L of mash water with a whopping ~160 ppm Alkalinity (as CaCO3) I can't imagine where sufficient grist acidity materialized whereby to mash at 5.14 pH. Nor can I imagine hitting 4.81 pH post boil. I can speculate that your pH meter went wonky on you at some juncture following your initial mash pH reading. Or alternately I can speculate that you forgot to add NaHCO3 and CaCO3 to your mash water, and thereby it had no Alkalinity. Or I can speculate that (since CaCO3 is quite highly insoluble in water, and thereby does not contribute nearly the calcium or alkalinity predicted for it by software) that this may have played some part.

Note: Most of us have completely abandoned the use of CaCO3 due to its serious insolubility issue. I believe Kai Troester (Braukaiser) ran a series tests wherein it only delivered at best about half of its software projected alkalinity and calcium content.

Thanks. I believe I put NaHCO3 and CaCO3 in the mash water before mixing with malt, ha. However, I remember that the salts were seen clearly in the water and undissolved in the water when mixing the grains, so which probably made the alkalinity and calcium to not working efficiently, eventually leads to low PH. And the high PH reading at mash could be explained by taking the sample too early and probably the sample contains large amount of undissolved CaCO3. One question here is that if I insist to use CaCo3, should I make sure all of them are dissolved in the water like you cannot see the white salt in the water?

Another question is that normally before and after boil the PH should drop abount 0.3, like John P states ub How to Brew . No? Because the batches I brewed verified this.

 

[Miles_1111]

The 20 minute mark is still too early and pH has not stabilized. While it’s okay to measure that early, I found that pH is fairly stable after the 45 minute mark.

Absolutely DO NOT chase pH during a mash. Use software or experience to properly plan the water amendments and then monitor how they turn out. As I pointed out above, you can’t tell how the pH will end up from an early measurement. Don’t try.

If you take sample at 45 mins, is that mash PH or after-mash PH? I think there is around 0.2 drop in PH before mash and after mash ?

 

[Silver_Is_Money]

If you take sample at 45 mins, is that mash PH or after-mash PH? I think there is around 0.2 drop in PH before mash and after mash ?

I don't believe this to be a truism. It must be grist acidity dependent with respect to target pH. Some of my measures have clearly shown just the opposite.

 

[Silver_Is_Money]

Another question is that normally before and after boil the PH should drop abount 0.3, like John P states ub How to Brew . No? Because the batches I brewed verified this.

There is some fall, but I don't believe this to be a truism. It is likely not even a good generalization. If you mash at about pH 5.7 or 5.8 you "may" see a 0.3 pH point drop across the boil, but if you mash at pH 5.2 you "may" see a drop across the boil of 0.1 pH points or less. And if you mash at or below pH 5.2 you may not see any pH drop across the boil. This per a peer reviewed study.

Some to perhaps much of this is related to how much calcium you have added, as well as if magnesium is added. At least one peer reviewed study indicated that added magnesium suppresses calcium's ability to depress pH during the mash, but this suppression reverses itself during the boil and causes a greater drop at that stage.

 

[Miles_1111]

There is some fall, but I don't believe this to be a truism. It is likely not even a good generalization. If you mash at about pH 5.7 or 5.8 you "may" see a 0.3 pH point drop across the boil, but if you mash at pH 5.2 you "may" see a drop across the boil of 0.1 pH points or less. And if you mash at or below pH 5.2 you may not see any pH drop across the boil. This per a peer reviewed study.

Some to perhaps much of this is related to how much calcium you have added, as well as if magnesium is added. At least one peer reviewed study indicated that added magnesium suppresses calcium's ability to depress pH during the mash, but this suppression reverses itself during the boil and causes a greater drop at that stage.

Thanks Larry. Guess I have many more batches to brew to testify them, ha.

 

[ScrewyBrewer]

The 20 minute mark is still too early and pH has not stabilized. While it’s okay to measure that early, I found that pH is fairly stable after the 45 minute mark.

Does the question then become how much will the pH change by 0.05, 0.5, 1.5 pH? And if the change is great enough how much of a change in pH is correct.

 

[Brooothru]

There is some fall, but I don't believe this to be a truism. It is likely not even a good generalization. If you mash at about pH 5.7 or 5.8 you "may" see a 0.3 pH point drop across the boil, but if you mash at pH 5.2 you "may" see a drop across the boil of 0.1 pH points or less. And if you mash at or below pH 5.2 you may not see any pH drop across the boil. This per a peer reviewed study.

Some to perhaps much of this is related to how much calcium you have added, as well as if magnesium is added. At least one peer reviewed study indicated that added magnesium suppresses calcium's ability to depress pH during the mash, but this suppression reverses itself during the boil and causes a greater drop at that stage.

There's still a lot of confusion in my mind about what constitutes "good" mash pH targets. Usually my pre-mash planning results in pH 5.4-5.6. My setup is constant recirculation step mashes that run 1:30~1:45 hrs, so a sample taken at :20 mins is usually pretty accurate. If what I measure is more than about 0.2 off from my targeted pH 5.4-5.6, then I correct with lactic acid. I've only had one mash in the last 3 years measure more acidic than 5.2, so any correction has been due to elevated alkalinity. Pretreatment of mash water or use of acidulated malt usually gets me the pH I'm looking for without adding acid.

But what do I target after the mash? Usually there'll be a drop of 0.1 to 0.3 pH between pre-mash/post-lactic pH and the post-mash value. What is "desirable" for pre-boil and what should be targeted for post-boil? Is there a range of pH that encourages a better fermentation?

The emphasis always seems to be centered on mash, but there must be targeted values for pre-boil, post-boil and fermentation as well.

Brooo Brother

 

[Silver_Is_Money]

Play around with the "Kettle pH" tab (sheet) within 'Mash Made Easy' and see if 'Kettle pH Made Easy' helps you in any way. First set your water volume and temperature parameters, and then move up to the kettle pH adjusting section. A target of 5.15 pH is generally found to work well. Some target 5.1 pH. This software infers a hypothetical grist weight by design and intent, so it is fully usable with extract brewing as well as all-grain brewing. pH measurements of wort should comply with EBC standard 8.17 and be taken at 20 degrees C. (68 degrees F.)

 

[Brooothru]

Thanks, Larry. I had previously looked at your program but didn't realize or notice the kettle mash tab. So if I mash out and have a post-mash pH of say 5.3, should I look at additional lactic acid to achieve a more acidic kettle wort?

Brooo Brother

 

[Silver_Is_Money]

Thanks, Larry. I had previously looked at your program but didn't realize or notice the kettle mash tab. So if I mash out and have a post-mash pH of say 5.3, should I look at additional lactic acid to achieve a more acidic kettle wort?

Brooo Brother

I'm of the opinion that even for a mash at 5.3 it can still offer potential benefits. It aids in hot break, it aids the yeast in achieving a more long term storage stable and bacteria resistant final beer pH, and it benefits added finings (like Irish Moss, Whirlfloc, etc...) ability to clear your finished beer sooner and more completely. Finings are said to be highly pH specific.

 

[Silver_Is_Money]

Thanks, Larry. I had previously looked at your program but didn't realize or notice the kettle mash tab. So if I mash out and have a post-mash pH of say 5.3, should I look at additional lactic acid to achieve a more acidic kettle wort?

Brooo Brother

There are a plethora of tab (or sheet) related brewing utilities of interest and benefit in 'Mash Made Easy'. So many that you will need to tab over to the right to see them all. And I'm contemplating a few more which are being tested presently. A few are unique and will not be found elsewhere.

 

[h22lude]

The 20 minute mark is still too early and pH has not stabilized. While it’s okay to measure that early, I found that pH is fairly stable after the 45 minute mark.

Absolutely DO NOT chase pH during a mash. Use software or experience to properly plan the water amendments and then monitor how they turn out. As I pointed out above, you can’t tell how the pH will end up from an early measurement. Don’t try.

Does the question then become how much will the pH change by 0.05, 0.5, 1.5 pH? And if the change is great enough how much of a change in pH is correct.

I measure pH every 10 minutes. I find the mash pH is pretty stable around 20 minutes. After that it may change .02 or .03. I also recirculate so that may help stabilize the mash pH quicker.

 

[Miles_1111]

I measure pH every 10 minutes. I find the mash pH is pretty stable around 20 minutes. After that it may change .02 or .03. I also recirculate so that may help stabilize the mash pH quicker.

At the 20 mins mark ,do you also test if is the conversion is finished or undergoing by then?

 

[ScrewyBrewer]

It's safe to say that the majority of mash conversion will be complete after 20 minutes which coincides with sampling pH at that time.

 

[h22lude]

At the 20 mins mark ,do you also test if is the conversion is finished or undergoing by then?

No I don't use an iodine test. But by 20 minutes, I know it isn't done.

 

[Silver_Is_Money]

I mash for 60 minutes, and at that juncture I used to test with iodine regularly, but I never saw a negative test, so now I only check it with iodine about once in a blue moon. Perhaps one time a year...

There is one respected forum participant who claims that cutting off the mash at 40 minutes makes for beer with greater mouthfeel, since at that juncture the enzymes haven't been given enough time to chop up the starch molecules into quite as small molecules while in their process of performing saccharification. I've never attempted this to verify it.