Yet more evidence that commercial brewers do not mash at 5.2 to 5.6 pH ...

[eric19312]

With respect, I am not sure your example is necessarily the best one. Under the conditions you describe - where you pointed out the flaw was there and the exact identity of the flaw - you introduced a massive bias. Of course your friend would find it. I have a terrible palate and I probably would have found it, even if it was entirely in my head

The intention of your point is well taken though, and I find that you are actually supporting the points made regarding the panel tasting. The distinction is where the intended threshold of detection by the panel lies. There is no question that training/priming evaluators would increase sensitivity, but the point is that the Brulosophy panel method is not aimed at detecting minor or subtle, it seems designed by purpose to detect the obvious (as for the why, see post #228 by @Qhrumphf - summed up well there). When you think about it, if detecting the obvious is the goal, then a panel of unqualified "Joe-six-pack " drinkers is exactly what you'd need.

I felt same way reading martin’s anecdote. A suggestion of a flavor coming from someone with his level of credibility is going to create that flavor in my mind whether it’s really there or not.

 

[eric19312]

The derail has at least illustrated the different levels of significance of actual, measurable effects of changes in process, and suggests which categories mash pH prediction/control and simple kettle pH adjustment may fall into. I would venture that the effects of the latter would be more likely to be detected by, and even important to, even our new friend Joe Sixpack. There you go, topic reintegrated.

Nicely played. It’s curious that we spend so much time worrying about mash pH IF it’s true you can get 90% of the desired result with a kettle pH adjustment.

All that mathematical modeling...grain coefficients...maybe all we really need to do is get “close enough” in the mash and then dial in pH in the kettle. Just perhaps getting perfect mash pH is really an issue we borrowed from the macro brewers who need high and perfectly repeatable yields.

 

[TheMadKing]

I would argue that you guys are still somewhat missing the point of how sensory panels are conducted at the pro level.

A real sensory analyzer is first trained to a known standard (40 hours of training at dogfish head for example)

Their sensitivities and blindnesses are characterized so that each taster has a profile of low thresholds and high thresholds.

Then they are asked to evaluate samples of beer for SPECIFIC attributes

"on a scale of 1-10 rate the level of perception of mercaptin in sample 1" then the same for sample 2

"on a scale of 1-10 rate the level of perception of acetaldehyde in sample 1" and then in sample 2

Etc

So at the end, there is a massive amount of data to analyze and then normalized (weighted for each flavor) using the taste panelist profiles

So at the end they are able to assign a statistical significance to the perception levels of specific flavors, and not, as Martin has pointed out a mystery factor of pick the one that's different

 

[hopjuice_71]

The derail has at least illustrated the different levels of significance of actual, measurable effects of changes in process, and suggests which categories mash pH prediction/control and simple kettle pH adjustment may fall into. I would venture that the effects of the latter would be more likely to be detected by, and even important to, even our new friend Joe Sixpack. There you go, topic reintegrated.

Yes, well played...

Nicely played. It’s curious that we spend so much time worrying about mash pH IF it’s true you can get 90% of the desired result with a kettle pH adjustment.

All that mathematical modeling...grain coefficients...maybe all we really need to do is get “close enough” in the mash and then dial in pH in the kettle. Just perhaps getting perfect mash pH is really an issue we borrowed from the macro brewers who need high and perfectly repeatable yields.

This is where I am at. A home brewer with some knowledge, but who still has pretty regular equipment, has some limitations. Adjusting kettle pH is a pretty easy was to overcome some limitations with really dialing in mash pHs. When I started taking care of kettle pH I noticed a difference immediately and, considering my crappy palate, felt it may be a large enough difference worthy of consideration for Joe Sixpack. However, I also acknowledge that I achieved what I was seeking and there was likely no small component of confirmation bias.

 

[Qhrumphf]

I would argue that you guys are still somewhat missing the point of how sensory panels are conducted at the pro level.

A real sensory analyzer is first trained to a known standard (40 hours of training at dogfish head for example)

Their sensitivities and blindnesses are characterized so that each taster has a profile of low thresholds and high thresholds.

Then they are asked to evaluate samples of beer for SPECIFIC attributes

"on a scale of 1-10 rate the level of perception of mercaptin in sample 1" then the same for sample 2

"on a scale of 1-10 rate the level of perception of acetaldehyde in sample 1" and then in sample 2

Etc

So at the end, there is a massive amount of data to analyze and then normalized (weighted for each flavor) using the taste panelist profiles

So at the end they are able to assign a statistical significance to the perception levels of specific flavors, and not, as Martin has pointed out a mystery factor of pick the one that's different

The triangle test still plays a role in a pro sensory program. But it's definitely only part of it. If, for example, I were to trial a different, cheaper 2-row malt, and want to be sure it's still true to brand for core beers. In that case, i want people blind to the variable being tested.

As opposed to a sensory panel for diacetyl. Which has its own biases to consider (beyond only using trained tasters), but being aware of what they're looking for isn't one of em.

 

[TheMadKing]

The triangle test still plays a role in a pro sensory program. But it's definitely only part of it. If, for example, I were to trial a different, cheaper 2-row malt, and want to be sure it's still true to brand for core beers. In that case, i want people blind to the variable being tested.

As opposed to a sensory panel for diacetyl. Which has its own biases to consider (beyond only using trained tasters), but being aware of what they're looking for isn't one of em.

Thanks for the correction, I didn't mean to imply that the triangle test itself is the problem, but rather the way they are using it is. I would still argue that a full sensory evaluation of the flavor parameters in each sample would provide better data than simply "pick the one that's different", especially when they are looking at things like oxidation, or fermentation character

 

[bob1852]

I would still argue that a full sensory evaluation of the flavor parameters in each sample would provide better data than simply "pick the one that's different", especially when they are looking at things like oxidation, or fermentation character

So why aren't homebrewers doing that?

 

[mabrungard]

It strikes me as the same general mindset of many homebrewers with imperfect process and resulting flaws: "will it ruin my beer". A process problem is only a problem if the result is so severe to ruin the beer. An off-note is only present if so intense it ruins the beer. And if not, then clearly all is well, at least to them.

As a Master judge knows, ruined beer is one thing. But the differences between a great beer and a good beer often comes down to very minor flaws or characters. One of the things that I've noticed over the years, is that great brewers have the abilities to detect flaws in their beers and apply corrections to make great beers. Making beer is achievable to most brewers, but making great beer, is not. Unfocused studies and conclusions don't help brewers reach the next level.

 

[TheMadKing]

So why aren't homebrewers doing that?

So I, and many other do in a limited way, by tasting our beers critically and identifying flaws and making adjustments on the next batch as Martin said, but a sensory panel of 1 isn't a great method for doing statistical analysis to identify a process change.

 

[bob1852]

So I, and many other do in a limited way, by tasting our beers critically and identifying flaws and making adjustments on the next batch as Martin said, but a sensory panel of 1 isn't a great method for doing statistical analysis to identify a process change.

Trying to compare batches made weeks/months apart is problematic, too.

I try to do it every year with seasonal releases of commercial beers and it's a pointless exercise...

 

[Robert65]

If I might humbly presume to readdress the actual topic @Silver_Is_Money introduced, which I think is one of the more important ones I've seen in some time (and I do apologize for my catalyzing the derailment I think there are two areas that we need to flesh out: Do all mashes tend toward a certain pH value given sufficient time, rendering attempts at adjustment more problematic or irrelevant? And as to kettle adjustment timing, as we seem to understand the effects, at least, on hop utilization and fining, can we find definitive information regarding protein coagulation? (I'm trying, as time permits, to search out what I might have on file on the second point. First is IMO a big, undiscovered, country, but we could certainly compile a lot of data here if we all have good notes.)

 

[BrewnWKopperKat]

Recently someone posted a podcast link (and also a data link) to a guy who is university lab level researching and analyzing the impact of pellet hops, wherein he analytically determined that they isomerize far more quickly and efficiently during the boil than do whole/leaf hops.

Basic Brewing Radio Podcast, Nov 1, 2018; lead of the study is occasionally on /r/homebrewing.

edit: link: https://old.reddit.com/r/Homebrewin...0_minute_vs_30_minute_kettle/ew1e4tw/.compact

 

[Silver_Is_Money]

I have never observed mashes to trend toward a single pH value such as 5.4 over time. What I have seen is that for lighter colored beers the pH rises during the mash by as much as 0.2 points or perhaps even a fractional smidge more (from, for example 5.4 if measured early on, to 5.62 at mash terminus). And for seriously darker beers mashed at lower pH's in the range of 5.1(ish) pH I have never see the mash pH rise as the mash progresses, but rather if mash pH is initially this low it seems to stay this low, or perhaps at most rise ballpark 0.05 pH points by mash terminus. This difference in the degree of pH drift with respect to the progression of the mash may or may not actually correlate to wort color at all. It may simply be that once a certain lower end mash pH is achieved early on within the mash, the pH stays low regardless of EBC/SRM wort color. I've only seen this correlate to color because (out of fear with regard to adding base substances to the mash) I have failed (to date) to add sufficient baking soda or Ca(OH)2 to my stouts to get beers such as robust stouts to at or above 5.2 pH. I no longer have this fear, and going forward I will be hitting them with much higher loads of baking soda or Ca(OH)2, commensurate with the advice of 'Mash Made Easy', because if I overshoot the mark a bit I can reel it back in with 'Kettle pH Made Easy' before or during the boil. Then it "may" be that I will observe the same sort of 5.4 to 5.6 rise across the progression of the mash for truly dark and robustly deep roast and caramel malt rich beers as for the likes of Pilsner and Kolsch.

All mash pH's mentioned above are as observed at room temperature.

 

[TheMadKing]

I have never observed mashes to trend toward a single pH value such as 5.4 over time. What I have seen is that for lighter colored beers the pH rises during the mash by as much as 0.2 points or perhaps even a fractional smidge more (from, for example 5.4 if measured early on, to 5.62 at mash terminus). And for seriously darker beers mashed at lower pH's in the range of 5.1(ish) pH I have never see the mash pH rise as the mash progresses, but rather if mash pH is initially this low it seems to stay this low, or perhaps at most rise ballpark 0.05 pH points by mash terminus. This difference in the degree of pH drift with respect to the progression of the mash may or may not actually correlate to wort color at all. It may simply be that once a certain lower end mash pH is achieved early on within the mash, the pH stays low regardless of EBC/SRM wort color. I've only seen this correlate to color because (out of fear with regard to adding base substances to the mash) I have failed (to date) to add sufficient baking soda or Ca(OH)2 to my stouts to get beers such as robust stouts to at or above 5.2 pH. I no longer have this fear, and going forward I will be hitting them with much higher loads of baking soda or Ca(OH)2, commensurate with the advice of 'Mash Made Easy', because if I overshoot the mark a bit I can reel it back in with 'Kettle pH Made Easy' before or during the boil. Then it "may" be that I will observe the same sort of 5.4 to 5.6 rise across the progression of the mash for truly dark and robustly deep roast and caramel malt rich beers as for the likes of Pilsners and Kolsches.

All mash pH's mentioned above are as observed at room temperature.

All of this is assuming RO water with no alkalinity, is used correct?

Much of the work that AJ put forth was more about neutralizing alkalinity in brewing water than about targeting a specific pH.

so just something to bear in mind that not all water is equal and these statements need to be conditional.

 

[brewbama]

FWIW, Here are some pH and gravity readings I’ve taken for some mashes lately.

This is the main mash that I have adjusted distilled water for a taste-color profile and pH using Bru’n Water. After the main mash I completely drain the MLT and underlet to batch sparge. I do not adjust for kettle pH but after this discussion I may begin that technique.

This information was gathered, cooled to room temp, and noted using a calibrated MW101. There may have been variations in “room temp” as I did not measure. My intent is to monitor mash progress vs gather scientific data.

The grist for the Pale Ales was the same. In fact I brewed a series of Pale Ales over the Summer to calibrate my system and processes. The information for those were all very similar which was the point. All other grists varied as did the information.

Schwarzbier
20 min 1.049 5.33 pH
40 min 1.058 5.48 pH
60 min 1.062 5.38 pH
80 min 1.066 5.27 pH
90 min 1.067 5.30 pH

Helles Bock
20 min 1.057 5.29 pH
40 min 1.069 5.28 pH
60 min 1.076 5.28 pH
80 min 1.081 5.25 pH
90 min 1.081 5.19 pH

Dunkel
20 min 5.1 pH 1.048
40 min 5.1 pH 1.056
70 min 5.1 pH 1.062
90 min 5.1 pH 1.065
100 min 1.065

Pils
20 min 1.050 5.21
40 min 1.057 5.23
60 min 1.063 5.29
80 min 1.065 5.24
90 min 1.067

Pale Ale
20 min 5.52 pH 1.050
40 min 5.43 pH 1.060
60 min 5.43 pH 1.065
80 min 5.35 pH 1.070
90 min 5.38 pH 1.070

Pale Ale
20 min 5.40 pH 1.057
40 min 5.41 pH 1.064
60 min 5.42 pH 1.067
80 min 5.37 pH 1.070
90 min 5.37 pH 1.070

 

[Silver_Is_Money]

All of this is assuming RO water with no alkalinity, is used correct?

I have been mineralizing RO water, and also acidifying for grists akin to Pilsner, and adding some baking soda (though not nearly enough) for the likes of stouts. I often find that mid-range SRM beers need no pH adjustment (when targeting a room temperature measured 5.4, and accepting as low as room temperature 5.2), but this will all change now that I intend to target 5.65 pH in the mash as measured at room temperature. I will however be assisted in transitioning to 5.65 pH via the use of a water blend comprised of 25% of my high alkalinity well water and 75% RO going forward.

 

[Silver_Is_Money]

FWIW, Here are some pH and gravity readings I’ve taken for some mashes lately.

This is the main mash that I have adjusted distilled water for a taste-color profile and pH using Bru’n Water. After the main mash I completely drain the MLT and underlet to batch sparge. I do not adjust for kettle pH but after this discussion I may begin that technique.

This information was gathered, cooled to room temp, and noted using a calibrated MW101. There may have been variations in “room temp” as I did not measure. My intent is to monitor mash progress vs gather scientific data.

The grist for the Pale Ales was the same. In fact I brewed a series of Pale Ales over the Summer to calibrate my system and processes. The information for those were all very similar which was the point. All other grists varied as did the information.

Schwarzbier
20 min 1.049 5.33 pH
40 min 1.058 5.48 pH
60 min 1.062 5.38 pH
80 min 1.066 5.27 pH
90 min 1.067 5.30 pH

Helles Bock
20 min 1.057 5.29 pH
40 min 1.069 5.28 pH
60 min 1.076 5.28 pH
80 min 1.081 5.25 pH
90 min 1.081 5.19 pH

Dunkel
20 min 5.1 pH 1.048
40 min 5.1 pH 1.056
70 min 5.1 pH 1.062
90 min 5.1 pH 1.065
100 min 1.065

Pils
20 min 1.050 5.21
40 min 1.057 5.23
60 min 1.063 5.29
80 min 1.065 5.24
90 min 1.067

Pale Ale
20 min 5.52 pH 1.050
40 min 5.43 pH 1.060
60 min 5.43 pH 1.065
80 min 5.35 pH 1.070
90 min 5.38 pH 1.070

Pale Ale
20 min 5.40 pH 1.057
40 min 5.41 pH 1.064
60 min 5.42 pH 1.067
80 min 5.37 pH 1.070
90 min 5.37 pH 1.070

Interesting that your higher mash pH beers tend to rise in pH up to 60 minutes of mashing, and then abruptly fall again from 60 minutes to 90 minutes of mashing. I don't see the drop at the end since I only mash for 60 minutes. Also interesting is that (just as I noticed) mash pH variation with mashing time is greater for your higher mash pH's, and lesser to eventually non existent by pH 5.1.

But you are not confirming anywhere near a rise from 5.4 to 5.62 pH. What you do confirm is that none of these beers trended to 5.4 over time.

You are also gaining efficiency up to about the 80 minute mark of the mash. Perhaps I'll need to consider extending my mashes from 60 to 80 minutes.

 

[Silver_Is_Money]

There is something about hitting a room temperature measured 5.1 pH, as now it appears that by achieving 5.1 pH there is not only zero further drop to be expected across the duration of the boil, but the same also now appears to be the case for across the duration of the mash.

 

[Silver_Is_Money]

So maybe all those amateur professionals who don't bother messing with mash pH are on to something!

They certainly are, but only if they somehow manage to get to 5.0-5.2 pH by the end of the boil and cooling.

 

[Silver_Is_Money]

.... I think there are two areas that we need to flesh out: Do all mashes tend toward a certain pH value given sufficient time, rendering attempts at adjustment more problematic or irrelevant? And as to kettle adjustment timing, as we seem to understand the effects, at least, on hop utilization and fining, can we find definitive information regarding protein coagulation?

A third question yet to be resolved would be: Is Kunze correct in stating that due to hop isomerization characteristics and requirements the post mash and lautering acidification to 5.1-5.2 pH step should be carried out toward the tail end of the boil, or can this acidification be successfully done immediately before the boil, or (as Bamforth states, in clearly misquoting Kunze) at 30 minutes remaining within the boil.

 

[brewbama]

Interesting that your higher mash pH beers tend to rise in pH up to 60 minutes of mashing, and then abruptly fall again from 60 minutes to 90 minutes of mashing. I don't see the drop at the end since I only mash for 60 minutes. Also interesting is that (just as I noticed) mash pH variation with mashing time is greater for your higher mash pH's, and lesser to eventually non existent by pH 5.1.

But you are not confirming anywhere near a rise from 5.4 to 5.62 pH. What you do confirm is that none of these beers trended to 5.4 over time.

You are also gaining efficiency up to about the 80 minute mark of the mash. Perhaps I'll need to consider extending my mashes from 60 to 80 minutes.

You’re perception mirrors mine.

I lengthened my mash to 90 min because I was still gaining points at 60. I should add that I recirculate thru a RIMS at about .7 gpm, step mash, crush fairly course (.040), and mash at 1.75/1 water/grist ratio.

 

[hopjuice_71]

A third question yet to be resolved would be: Is Kunze correct in stating that due to hop isomerization characteristics and requirements the post mash and lautering acidification to 5.1-5.2 pH step should be carried out toward the tail end of the boil, or can this acidification be successfully done immediately before the boil, or (as Bamforth states, in clearly misquoting Kunze) at 30 minutes remaining within the boil.

Posted this a bit earlier but it may have flown under the radar: https://www.tandfonline.com/doi/pdf/10.1094/ASBCJ-64-0029?needAccess=true

Abstract: "Various factors were examined to determine their impact on the rate of isomerization of α-acids (humulones) to iso-α-acids (isohumulones) during kettle boiling. A model wort boiling system was used that employed multiple 12-mL stainless steel vessels to heat samples (α-acids in an aqueous, pH-buffered solution with other compounds included as specified) at 100°C for 140 min. Concentrations of humulones and isohumulones were quantified at discrete time points using HPLC. Of the factors tested (glucose, maltose, calcium, and pH ranging from 4.8 to 6.0), none were shown to affect the rate of production of iso-α-acids. While pH had a marked effect on the concentrations of α-acids as measured, the differences may be attributed to solubility issues (since the solubility limit was approached and exceeded) that did not appear to affect the rate of iso-α-acid production."

Hop isomerization may not be a hugely important consideration at the homebrew level.

 

[Robert65]

You’re perception mirrors mine.

I lengthened my mash to 90 min because I was still gaining points at 60. I should add that I recirculate thru a RIMS at about .7 gpm, step mash, crush fairly course (.040), and mash at 1.75/1 water/grist ratio.

My standard mash is a 30 minute beta rest (temperature depending on gelatinization temperature of the malt, but ~64°C,) 15 minutes 67°C, 30 minutes 72°C, 15 minutes 76°C, with 1°C/minute ramps, and I gain easily 1°P even through the last step. But this probably does not entirely reflect continued conversion, but continued diffusion, and I might suspect that proper lautering could achieve the same degree of extraction with a shorter mash program. But I don't have any data to support this, and @brewbama's demonstrated improvement over time even with continuous recirculation (I don't have a recirculating system) may suggest otherwise.

 

[couchsending]

A third question yet to be resolved would be: Is Kunze correct in stating that due to hop isomerization characteristics and requirements the post mash and lautering acidification to 5.1-5.2 pH step should be carried out toward the tail end of the boil, or can this acidification be successfully done immediately before the boil, or (as Bamforth states, in clearly misquoting Kunze) at 30 minutes remaining within the boil.

I think this also depends on a few variables.

Malt:

Malts with higher levels of the DMS precursor that need longer boils (Pils) you’re gonna want a higher preboil pH to help with conversion of SMM to DMS which happens faster at a higher pH. However not too high as the character of the bitterness can change at elevated levels.

Hops:

If you’re using low alpha hops for bitterness (using nothing but Saaz in a Czech Pils for instance) you’d want that slightly higher pH to optimize alpha acid isomerization.

The beer you’re making...

If it’s a highly hopped IPA or IIPA with no Pilsner malt personally I’d lower the pre boil pH to around 5.2 and the depending on the hop load you add during the boil/WP you’re gonna need to add a decent amount of acid at the end of the boil, and depending on your DH load maybe even with a DH charge as well.

Always trying to check out brewing logs at the breweries who’s beer I think is really well executed. Can’t tell you the number of them that always list KO pH between 5.1 and 4.9. From hoppy beers to huge stouts and everything in between.

 

[Silver_Is_Money]

Posted this a bit earlier but it may have flown under the radar: https://www.tandfonline.com/doi/pdf/10.1094/ASBCJ-64-0029?needAccess=true

Abstract: "Various factors were examined to determine their impact on the rate of isomerization of α-acids (humulones) to iso-α-acids (isohumulones) during kettle boiling. A model wort boiling system was used that employed multiple 12-mL stainless steel vessels to heat samples (α-acids in an aqueous, pH-buffered solution with other compounds included as specified) at 100°C for 140 min. Concentrations of humulones and isohumulones were quantified at discrete time points using HPLC. Of the factors tested (glucose, maltose, calcium, and pH ranging from 4.8 to 6.0), none were shown to affect the rate of production of iso-α-acids. While pH had a marked effect on the concentrations of α-acids as measured, the differences may be attributed to solubility issues (since the solubility limit was approached and exceeded) that did not appear to affect the rate of iso-α-acid production."

Hop isomerization may not be a hugely important consideration at the homebrew level.

This would seem to imply that it wouldn't matter if the wort acidification was accomplished pre-boil, mid boil, or at the end of the boil. In which case the prevention of excessive Mailard reactions would favor adding acid pre-boil. But I just came across this quoted excerpt by Briggs etc... on page 327 of the book titled "Brewing Science And Practice", published in 2004 (see link to book below the quote):

The reduction of wort pH during the boil reduces the colour, gives beer with a `cleaner' flavour, and a better`break' formation, but hop utilization is reduced unless pre-isomerized preparations are used.

So there do seem to be varying opinions. Better flavor, better break, lower color, but less isomerization may mean that to get the full impact of the stated benefits (which seem significant) one will likely need to acidify pre-boil and then add a tad more hops.

http://vinic.com/files/books/Brewing_Science_and_Practice__2004_.pdf

 

[hopjuice_71]

This would seem to imply that it wouldn't matter if the wort acidification was accomplished pre-boil, mid boil, or at the end of the boil. In which case the prevention of excessive Mailard reactions would favor adding acid pre-boil. But I just came across this quoted excerpt by Briggs etc... on page 327 of the book titled "Brewing Science And Practice", published in 2004 (see link to book below the quote):



So there do seem to be varying opinions.

http://vinic.com/files/books/Brewing_Science_and_Practice__2004_.pdf

Yes, as there always are. I had a hard time finding the exact section you were referring to in the book, so I couldn't find the source they were citing for those details. However, here is what I think. The paper I linked was published in 2006. They actually directly address a paper published in 1986 by McMurrough et al, which reports reduced hop utilization at lower pH. The more recent Shellhammer paper quite convincingly addresses a perceived flaw in that older paper, namely not directly reporting iso-a-acid concentrations and reporting a ratio that did not account for the changes in a-acid solubility with pH at lower temperatures (where measurements were actually made) hence giving the appearance of reduced yield. I am certain Briggs was going on the older paper, or another one, given your version was published before the Shellhammer paper.

I tend to agree with your comments on timing, but there may be other factors (?)

 

[Silver_Is_Money]

I had a hard time finding the exact section you were referring to in the book, so I couldn't find the source they were citing for those details.

Page 327, second paragraph from the bottom of that page.

But as you stated, the more recently published Shellhammer paper seems to nix the isomerization "hit" issue, favoring acidification pre-boil.

 

[hopjuice_71]

Page 327, second paragraph from the bottom of that page.

Seems I skimmed right past it. Unfortunately, a citation is not provided for those claims. Hopefully you have a chance to read the paper I linked. Previous literature is quite well handled and the conclusions are well supported.

 

[Silver_Is_Money]

Hopefully you have a chance to read the paper I linked. Previous literature is quite well handled and the conclusions are well supported.

They are asking for $50 to download it.

 

[ScrewyBrewer]

The grist for the Pale Ales was the same. In fact I brewed a series of Pale Ales over the Summer to calibrate my system and processes. The information for those were all very similar which was the point. All other grists varied as did the information.

Pale Ale
20 min 5.52 pH 1.050
40 min 5.43 pH 1.060
60 min 5.43 pH 1.065
80 min 5.35 pH 1.070
90 min 5.38 pH 1.070

Pale Ale
20 min 5.40 pH 1.057
40 min 5.41 pH 1.064
60 min 5.42 pH 1.067
80 min 5.37 pH 1.070
90 min 5.37 pH 1.070

@brewbama there's seems to be a typo somehow the two Pale Ale results are hardly similar.