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Author Topic: Potential of Hydrogen (Another pH thread)  (Read 3757 times)

Offline Robert

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Re: Potential of Hydrogen (Another pH thread)
« Reply #15 on: February 19, 2018, 07:11:22 pm »
Kunze states that the malt and water will naturally set up a pH of 5.6-5.8 which should be lowered to 5.2, but also that extract potential is highest at 5.4-5.6.  He doesn't have to mention temperature.  Nobody does. It is, and always has been the pH at ROOM temp that is the reference. The article that started this is bizarre, but not surprising given what it is, and the passage from Briggs et al is hard to explain or to understand really.  But Briggs again is not a reference to be sought out for modern, even British, processes and materials. (But I don't think it can have meant what it seems to.)  You can look at any text -- DeClerck, Kunze, Narziss, whatever -- and the matter is settled.  The texts are not at all vague or confusing, none of them.  The BYO Wizard guy is vague and confused.

Siebel sells DeClerck reprints pretty cheap, and can get you a Kunze for under $300 including shipping.
Rob Stein
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Big Monk

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Re: Potential of Hydrogen (Another pH thread)
« Reply #16 on: February 19, 2018, 08:12:13 pm »
I find the interesting part of the author's response not about ATC or the fact that we should be measuring mash pH at room temp, but rather that the author seemed to double down on optimal mash pH at room temp being between 5.5 and 5.8 and cites Malting & Brewing Science as that reference. 

Does Kunze not reference temperature in Technology Brewing and Malting in regards to mash pH?  Where are the citations from other textbooks that contradict the Malting & Brewing Science citation?


  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."

I’ve been down this road before and I have sections jotted down from at least 6 texts. I’ll try to dig those quotes out and post them here.
Thanks.  It's not that I believe the article over all the expertise on this forum, it's more that I can't believe that ALL of the texts are as vague or confusing as indicated in the article. 

I really need to drop some cash on a good brewing text.  I have lots of books on brewing, but I'd like to have a serious "school worthy" text.

Any recommendations or warnings?  I'm leaning Kunze. 

  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."


I’d say you should own Kunze, DeClerck, and Fix are not a bad triumvirate. Bamforth “Freshness” is great as well.
« Last Edit: February 19, 2018, 08:14:41 pm by Big Monk »

Online dmtaylor

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Re: Potential of Hydrogen (Another pH thread)
« Reply #17 on: February 19, 2018, 08:16:15 pm »
I have analyzed and discussed this topic in great detail previously on other forums.  In a nutshell, I've concluded:

1) Ashton Lewis' article brings up a lot of great points and numbers that have been misunderstood for too long, and will remain misunderstood because the masses will refuse to listen;

2) My own experiments confirm that measurement at mash temp is about 0.25 units lower than at room temp, just as Mr. Lewis states; and

3) I have a significant degree of doubt as to whether the mash pH affects final beer flavor very much.  More experiments would be appropriate to confirm; however, I also know many xbmts have already been run by Brulosophy etc. where the average joe couldn't taste a difference.

As with SO MANY things in brewing....... this topic deserves further questioning and experimentation because the magical pH numbers very likely have way too much emphasis placed on them.  I don't know the answers yet for sure.  However I'm skeptical as to how much the topic matters... so long as we are someplace between like 5.0 and 5.8 or some range very very broad like that.
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline Robert

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Re: Potential of Hydrogen (Another pH thread)
« Reply #18 on: February 19, 2018, 08:23:34 pm »
I find the interesting part of the author's response not about ATC or the fact that we should be measuring mash pH at room temp, but rather that the author seemed to double down on optimal mash pH at room temp being between 5.5 and 5.8 and cites Malting & Brewing Science as that reference. 

Does Kunze not reference temperature in Technology Brewing and Malting in regards to mash pH?  Where are the citations from other textbooks that contradict the Malting & Brewing Science citation?


  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."

I’ve been down this road before and I have sections jotted down from at least 6 texts. I’ll try to dig those quotes out and post them here.
Thanks.  It's not that I believe the article over all the expertise on this forum, it's more that I can't believe that ALL of the texts are as vague or confusing as indicated in the article. 

I really need to drop some cash on a good brewing text.  I have lots of books on brewing, but I'd like to have a serious "school worthy" text.

Any recommendations or warnings?  I'm leaning Kunze. 

  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."


I’d say you should own Kunze, DeClerck, and Fix are not a bad triumvirate. Bamforth “Freshness” is great as well.
I have to either disagree or at least propose a caveat on Fix.   He is not a primary source, nor a professional in any field related to brewing science.  He is (was) a compiler, offering  almost an index or synopsis of key subjects of emerging interest to fellow homebrewers.  But he made enough glaring errors in his writings outside of _Principles of Brewing Science_ (misinterpretations of source material) to make me wary of taking anything he wrote as more than a pointer to a subject worthy of further study.  But worth having on the shelf.
Rob Stein
Akron, Ohio

I'd rather have questions I can't answer than answers I can't question.

Offline Robert

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Re: Potential of Hydrogen (Another pH thread)
« Reply #19 on: February 19, 2018, 08:29:55 pm »
I have analyzed and discussed this topic in great detail previously on other forums.  In a nutshell, I've concluded:

1) Ashton Lewis' article brings up a lot of great points and numbers that have been misunderstood for too long, and will remain misunderstood because the masses will refuse to listen;

2) My own experiments confirm that measurement at mash temp is about 0.25 units lower than at room temp, just as Mr. Lewis states; and

3) I have a significant degree of doubt as to whether the mash pH affects final beer flavor very much.  More experiments would be appropriate to confirm; however, I also know many xbmts have already been run by Brulosophy etc. where the average joe couldn't taste a difference.

As with SO MANY things in brewing....... this topic deserves further questioning and experimentation because the magical pH numbers very likely have way too much emphasis placed on them.  I don't know the answers yet for sure.  However I'm skeptical as to how much the topic matters... so long as we are someplace between like 5.0 and 5.8 or some range very very broad like that.
Dave, my experience, like your mileage, varies.  I find definite effects on beer quality relating to pH. And my observations show a pH displacement nearer -0.18, but we're both well off the dogmatic -0.35 based on one anecdotal table in DeClerck (still the only source I know.)
Rob Stein
Akron, Ohio

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Re: Potential of Hydrogen (Another pH thread)
« Reply #20 on: February 19, 2018, 08:32:20 pm »
my observations show a pH displacement nearer -0.18, but we're both well off the dogmatic -0.35 based on one anecdotal table in DeClerck (still the only source I know.)

The 0.35 difference is totally wrong.  Kai Troester, Gordon Strong, and John Palmer all quote values of 0.18-0.25, which agrees with the experience of both you and I as well.  0.35 is way off.
Dave

The world will become a much more pleasant place to live when each and every one of us realizes that we are all idiots.

Offline Robert

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Re: Potential of Hydrogen (Another pH thread)
« Reply #21 on: February 19, 2018, 09:15:28 pm »
And what remains important is that all references in the literature are to pH measured at ROOM temperature;  whatever the displacement is, is therefore irrelevant; and, as you suggest, Dave, we can still debate the effects of pH on beer quality.  We just need to have a standardized understanding of our reference conditions in order to do that.
Rob Stein
Akron, Ohio

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Offline JT

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Re: Potential of Hydrogen (Another pH thread)
« Reply #22 on: February 19, 2018, 09:26:16 pm »


Kunze states that the malt and water will naturally set up a pH of 5.6-5.8 which should be lowered to 5.2, but also that extract potential is highest at 5.4-5.6.  He doesn't have to mention temperature.  Nobody does. It is, and always has been the pH at ROOM temp that is the reference.

Crazy.  Some of these texts are quite old.  Why on earth would they mention the differential and not specifically at what temp they measured mash pH? 

  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."


Offline Robert

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Re: Potential of Hydrogen (Another pH thread)
« Reply #23 on: February 19, 2018, 09:39:23 pm »


Kunze states that the malt and water will naturally set up a pH of 5.6-5.8 which should be lowered to 5.2, but also that extract potential is highest at 5.4-5.6.  He doesn't have to mention temperature.  Nobody does. It is, and always has been the pH at ROOM temp that is the reference.

Crazy.  Some of these texts are quite old.  Why on earth would they mention the differential and not specifically at what temp they measured mash pH? 

  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."
Short(ish) answer:  When the concept of pH was first introduced and adopted by brewing scientists in the 1920s, the only methods for measurement relied on chemical reactions carried out at room temperature. Later, instruments (like we now use) were developed that use electroconductivity as a PROXY for pH.  They can take a measurement at other temps.  But mash ACTUALLY has a displacement.  DeClerck reports a couple of tests demonstrating this, not to suggest that a correction factor might be available,  but to emphasize the need to take readings at room temp. Since then it seems that only assorted homebrewers and Ashton Lewis on a bad day (the dude is a UC Davis grad) have had trouble with this.
Rob Stein
Akron, Ohio

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Big Monk

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Re: Potential of Hydrogen (Another pH thread)
« Reply #24 on: February 20, 2018, 05:33:19 am »
From De Clerck:


Offline mabrungard

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Re: Potential of Hydrogen (Another pH thread)
« Reply #25 on: February 20, 2018, 06:21:12 am »
The term: STP is widespread in chemistry. Standard temperature and pressure are important aspects since so many parameters can vary with those components. Its a stretch to assume that pH measurements were not conducted generally with respect to STP unless their deviation is specifically called out. Now, if there were only a true 'standard' to the STP. Unfortunately, even that isn't fixed. But generally, somewhere around room-temp and sea level atmospheric pressure is typically used.

The pH offset between mashing temp and STP cannot be a fixed number unless a mashing temperature is applied. I'm assuming that most can recognize that the offset is zero at room temperature and it grows with increasing temperature. So the 0.18 to 0.35 offset range may have validity...but at differing temps. 
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Re: Potential of Hydrogen (Another pH thread)
« Reply #26 on: February 20, 2018, 08:20:14 am »
I agree with every comment regarding STP.  It is a scientific convention -- whenever a scientist fails to mention temperature and pressure, it's because conditions are at STP.  If not at STP but the conditions are not specified, that would be very sloppy science indeed.

I've come totally full circle on this whole thing, arriving at more questions, including a key one: who cares!?  View more continuing ramblings here:

https://www.homebrewtalk.com/forum/threads/dec-17-byo-response-to-mash-ph-questions.638811/
Dave

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Offline JT

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Re: Potential of Hydrogen (Another pH thread)
« Reply #27 on: February 20, 2018, 06:47:14 pm »



I've come totally full circle on this whole thing, arriving at more questions, including a key one: who cares!? 

Indeed, my beer tastes good!  I do appreciate all the replies.  This was definitely one of those WTH moments that I had to share and get a sanity check on. 


  "If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."


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Re: Potential of Hydrogen (Another pH thread)
« Reply #28 on: February 20, 2018, 07:04:44 pm »
Don’t worry.  Mr. wizard and I went rounds and rounds about our recent article.  He would come back with edits that would literally blow my mind.  I.e.  oxygen solubility at boil is not zero. 


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