pH: How important is adjusting for pH

[ThirstyPawsHB]

I don't check for pH, but after using Brew'nWater and RO as a base, beer clearly got better.

 

[ajdelange]

I propose a simple test. Brew....

That test has been performed thousands and thousands of time over the course of the history of brewing. We don't have the written results of those tests but we do know that thousands of breweries around the world take steps to acidify the mash, including those that have close to 0 alkalinity water and we also know that those breweries who decarbonate their water do it too. We do know that the authors of brewing texts (e.g. Kunze) state that most beers will require some acid and we have our own experiences (the homebrewers who have reported that all the flavors become brighter). So what do we think the outcome of the experiment will be?

Now hotdog has discovered that all these people are wrong. They don't have to do this. All they have to do is acidify the wort. This is an extremely significant discovery which needs to be promulgated throughout the brewing world. A few brewing scientists may see it here but it needs to be published in the literature.

As to the actual performance of the test I certainly encourage home brewers to experiment to see what the effects of pH control on their own beers can be. The experiment they should to is to make three beers the same except that in the first they do nothing to adjust pH, in the second they set the pH of the mash to 5.4 - 5.5 and in the third they do nothing with regard to the mash pH but only adjust kettle pH to 5.2 or thereabouts.

 

[ajdelange]

THIS. There is a lot of concern over pH, when the yeast is just going to pull it to whatever level it wants anyway. Get your pH into the conversion range, maybe adjust for hop utilization if desired. Acidify in the kettle, or don't.

Do you want your yeast to be making beer or making the acid you neglected to add in the mash/kettle?

The best use I've found for my pH meter recently is telling me when a kettle sour is ready to add a sacc strain.

That's only because you are unaware of the many other things a pH meter can do for you. Not to say that the one thing you have found isn't an example of one of the many benefits a good pH meter confers.

 

[ajdelange]

In my further ponderance upon this bewilderment, malts purchased in bulk likely come with complete ISO9000 (type) certified analysis by lot, making it less likely that breweries will actually need to do such in house testing (including DI pH) themselves.

It is certainly possible to make very good beer without the use of pH meters or any other analytical equipment. The concept of adding some sour mash to the main mash was discovered well before the concept of pH was. Thus it was known that adding acid to mash was a good thing to do well before the addition could be quantified accurately or measured. Similarly the concept of adding dark malts to beers made with waters that contribute some alkalinity and with malts that have higher alkalinities was discovered by trial and error as was the fact that one should strike when the brewer's reflection in the surface of the HLT water disappeared. The brewers that make the best beer have proper mash pH whether they are controlling it explicitly or setting it implicitly without fully understanding what they were doing.

Now don't hold 'professional' brewers in too high a regard. Many of these guys wound up as professional brewers by virtue of the fact that they number among their friends some doctors, lawyers and business men who enjoyed their home brew. One guy I know got his brewpub by virtue of having a rich wife (who subsequently took it away when she found out he was dipping his hydrometer in unauthorized 'worts'). I've been asked by 'professional' brewers if they should add metabisulfite to their water because it has a lot of chloride ion and why they need to cool a sample when their meter has ATC.

Further to all this I'll note that I sense, but cannot prove, that more professional brewers are taking pH mesurements now than used to be. Just as is the case with home brewers the availability of cheaper, more reliable pH meters has made them more available to professional brewers. I had one conversation with a pro who thought maybe he could get corporate to approve a Hach pH Pro+ at $125 so price is important to the pros too.

 

[sixhotdogneck]

I'm not sure that I can answer that question as in all my beers the water's alkalinity has been neutralized as has the malts'. I have, thus, never had to adjust the pH in the kettle. You are suggesting (I guess) that if I brew with alkalinity free water, ignore the alkalinity of the malts such that mash pH is higher than it ought to be I can correct that mistake by adjusting kettle pH? I can't and you can't either and neither can any other brewer. This explains why brewing textbooks (perhaps you should read one) discuss means of acidifying mash and why breweries and brewers all over the world do it. If you can advance any sensible argument (and malt alkalinity is less than water alkalinity is not a sensible argument because it isn't true) that supports your thesis then you know something that is very significant to an industry (and hobby) that has not perceived this wisdom. You need to write this up and submit to ASBC right away (I've got Bamforth's e-mail here somewhere - let me know if you want it).




If mash pH carries over into the boil (which it does) and I use a mash prediction calculator to set mash pH and thus boil pH to an appropriate value why is the calculator folly?
If this tool improves people's beer, where is the folly? If it were folly why would a professional brewing journal be interested in an article explaining the theory behind it?

I sometimes think your posts are simply bait. If they are intended to provoke intelligent discussion of the principles involved that's fine but some of the guys (and gals) here are new to all this and someone may take you seriously.

Adjusting mash pH is done for three reasons, fear of tannin extraction, supposed best enzyme action pH and adjustment of starting boil pH. The first two are bunk. Enzyme action occurs at the same rate until you get above pH ~6.5 at mash temperature. Tannin Extraction requires a low sugar liquid (i.e. not saturated with sugars) 180F+, pH > ~7 and a lengthy period of time (aka, fly sparging...).

Don't take my word for it, try it for yourself.

A lot of people in the homebrew world have made a lot of money on bunk spreadsheets and bunk books in which they make false assumptions and these then get spread throughout the homebrew world gossip chain.

 

[J-T]

Do you want your yeast to be making beer or making the acid you neglected to add in the mash/kettle?

That's only because you are unaware of the many other things a pH meter can do for you. Not to say that the one thing you have found isn't an example of one of the many benefits a good pH meter confers.

I entered some of those beers I neglected into competition a couple weeks ago. Maybe I'm just lucky? Cheers.

 

[ajdelange]

Adjusting mash pH is done for three reasons, fear of tannin extraction, supposed best enzyme action pH and adjustment of starting boil pH. The first two are bunk.

Yes, but the point is THE BREWING COMMUNITY IS UNAWARE OF THAT! Dozens of textbooks have been written in contradiction. Thousands of breweries are operating in contradition. You are ABSOLUTELY obliged to let the rest of the brewing world know they are wrong. You obviously understand this better than any of these people do and you are absolutely morally obliged to share you knowledge with them. That you have done so here is, of course, praiseworthy, but it is not enough. Professional brewing scientists won't see it and it is important that they be prevented from further misinforming brewers. As I offered earlier, I can give you Charlie Bamforth's e-mail address. Believe me, he will want to learn of your discovery, see your data etc and can see to it that it gets published in JASBC.

Enzyme action occurs at the same rate until you get above pH ~6.5 at mash temperature.

Here again you know something the rest of the world doesn't. It foolishly thinks that enzymes have peak activity in a certain range of pH depending on the enzyme. Here the significance of your discovery has much wider applications than in brewing as workers in many fields (including medicine) are laboring under this misconception. It is essential that the medical community, at least, be made aware of your discovery.

Tannin Extraction requires a low sugar liquid (i.e. not saturated with sugars) 180F+, pH > ~7 and a lengthy period of time (aka, fly sparging...).

I'm so upset and confused. I've been taken in for years by these pseudo scientists and didn't realize that controlling pH to reduce tannin extraction was bunk as you make clear above. But now you say it happens more at pH > 7 than below. My head is all filled with foolish notions about law of mass action and chemical potentials and that sort of stuff which I now see are all just that, stuff and nonsense. Please enlighten me here.

Don't take my word for it, try it for yourself.

I can't! When I do things like what you suggest I get results that confirm what the charlatans have been saying for decades so clearly my experiments aren't being done right. I'm going to need guidance here too.

A lot of people in the homebrew world have made a lot of money on bunk spreadsheets and bunk books in which they make false assumptions and these then get spread throughout the homebrew world gossip chain.

Well it's not just the home brewing world. The findings of professional brewing scientists and professional brewers pretty much mirror what the bunk homebrewing books say. There must be a conspiracy. What a disgrace!!!

OK - they say confession is good for the soul. I'm one of those bastards. I have taken money from Brewer's Publications and Elsevier for contributing to the deception of the brewing community. That's how I got to be so rich. Mea culpa, mea culpa.

 

[ajdelange]

I entered some of those beers I neglected into competition a couple weeks ago. Maybe I'm just lucky?

Well it's a bit more than luck. See No. 34. The fact that you produced a good beer means your mash pH was right (and you did a lot of other stuff right too) whether you paid any attention to it or not. But you didn't answer my question. Do you want your yeast fermenting or producing acid?

 

[sixhotdogneck]

Yes, but the point is THE BREWING COMMUNITY IS UNAWARE OF THAT! Dozens of textbooks have been written in contradiction. Thousands of breweries are operating in contradition. You are ABSOLUTELY obliged to let the rest of the brewing world know they are wrong. You obviously understand this better than any of these people do and you are absolutely morally obliged to share you knowledge with them. That you have done so here is, of course, praiseworthy, but it is not enough. Professional brewing scientists won't see it and it is important that they be prevented from further misinforming brewers. As I offered earlier, I can give you Charlie Bamforth's e-mail address. Believe me, he will want to learn of your discovery, see your data etc and can see to it that it gets published in JASBC.

Here again you know something the rest of the world doesn't. It foolishly thinks that enzymes have peak activity in a certain range of pH depending on the enzyme. Here the significance of your discovery has much wider applications than in brewing as workers in many fields (including medicine) are laboring under this misconception. It is essential that the medical community, at least, be made aware of your discovery.

I'm so upset and confused. I've been taken in for years by these pseudo scientists and didn't realize that controlling pH to reduce tannin extraction was bunk as you make clear above. But now you say it happens more at pH > 7 than below. My head is all filled with foolish notions about law of mass action and chemical potentials and that sort of stuff which I now see are all just that, stuff and nonsense. Please enlighten me here.

I can't! When I do things like what you suggest I get results that confirm what the charlatans have been saying for decades so clearly my experiments aren't being done right. I'm going to need guidance here too.

Well it's not just the home brewing world. The findings of professional brewing scientists and professional brewers pretty much mirror what the bunk homebrewing books say. There must be a conspiracy. What a disgrace!!!

OK - they say confession is good for the soul. I'm one of those bastards. I have taken money from Brewer's Publications and Elsevier for contributing to the deception of the brewing community. That's how I got to be so rich. Mea culpa, mea culpa.

You've used a lot of words but haven't said much of anything.

 

[J-T]

Well it's a bit more than luck. See No. 34. The fact that you produced a good beer means your mash pH was right (and you did a lot of other stuff right too) whether you paid any attention to it or not. But you didn't answer my question. Do you want your yeast fermenting or producing acid?

I want them doing what they have evolved to do, which is both.
And for the record, I'm not saying I don't pay attention to pH. I just don't worry about it much. The title of the thread asking the question if how important is pH adjustment, my answer would be: "somewhat." It is important enough to know the parameters and get in the ballpark. Not important enough to lose sleep over. I'm way more concerned with yeast health, sanitation, cold side oxidation, water mineral profile, ingredient quality and good old recipe formulation. Cheers.

 

[ajdelange]

You've used a lot of words but haven't said much of anything.

And I note that you haven't responded to any of them other than this comment. If you had a leg to stand on you would be offering your reasons for holding these positions.

In few words: you hold positions that are in conflict with accepted brewing (and other) science. Either you are wrong or the rest of the world is wrong. If the rest of the world is wrong it needs to be set right as a lot rides on this science in many discipllines. Simple enough?

 

[sixhotdogneck]

And I note that you haven't responded to any of them other than this comment. If you had a leg to stand on you would be offering your reasons for holding these positions.

In few words: you hold positions that are in conflict with accepted brewing (and other) science. Either you are wrong or the rest of the world is wrong. If the rest of the world is wrong it needs to be set right as a lot rides on this science in many discipllines. Simple enough?

Truth generally stands on its own. I have no need to engage in vitriolic discussions. Try it for yourself and report back.

 

[hopjuice_71]

Here again you know something the rest of the world doesn't. It foolishly thinks that enzymes have peak activity in a certain range of pH depending on the enzyme. Here the significance of your discovery has much wider applications than in brewing as workers in many fields (including medicine) are laboring under this misconception. It is essential that the medical community, at least, be made aware of your discovery.

Actually, sixhotdogneck is right here. I am part of that medical (research) community. I also research enzymes that convert polysaccharides, very much like the barley amylases. Enzymes very often have quite broad pH profiles, including those that are medically relevant. Scientists generally pick an estimated "peak" because it simplifies things for the end user; however, enzymes will typically operate quite well over sometimes very large pH ranges (depending on the catalytic mechanism they use). Think about it, an enzyme that has really tight operational parameters will not be a successful tool for an organism in a changing environment. This applies to the internal workings of humans as well.

Specific to the barley amylases, it is quite well documented in the primary literature that they have >90% activity over a pH range of ~4.5-6.5 (some of those authors are colleagues of mine). But, someone, sometime, was forced to pick a "peak," which is really just the centre point of a broad plateau in the pH profile. This pH optimum has persisted in brewing, maybe because on a massive commercial scale a 2% increase in activity translates to cost savings.

 

[Silver_Is_Money]

A lot of people in the homebrew world have made a lot of money on bunk spreadsheets and bunk books in which they make false assumptions and these then get spread throughout the homebrew world gossip chain.

My spreadsheet is both free and complete. There is no free sample hook followed by a full version line and sinker waiting in the wings that will cost you. Over the scant few weeks more than one full year that it has been made publicly available only a grand total of 3 people have contributed small donations in grateful appreciation of my effort, and after the obligatory 7% PayPal cut my net donations to date (spanning a bit more than one year) total to only $23.30. Yet I plod on, always trying hard to improve it and introduce new features and come up with better releases, while knowing full well that of the 2 to 3 people on average per day who will actually download it, right close to no one among them is willing to contribute donations to my effort. I'm always trying to answer questions as to its proper function, and listen to suggestions (both on this forum, and in private emails). And I'm quite often willing to run a forum members recipe through it and let him know my spreadsheets output advice. I've even endured some rather obvious (to me) spammers who rail on against my spreadsheet and its output by passing along clearly false and misleading information in regard to it, with their motives unknown to me, but each of such clearly painful none the less. With me it is a personal compulsion to better the product and bring happiness to the users who may find benefit in it that keeps me motivated, and allows me to endure such abuse. That I make roughly $23 per year for my effort indicates that my motivation to find and offer improvement is clearly not one of financial gain.

 

[sixhotdogneck]

My spreadsheet is both free and complete. There is no free sample hook followed by a full version line and sinker waiting in the wings that will cost you. Over the scant few weeks more than one full year that it has been made publicly available only a grand total of 3 people have contributed small donations in grateful appreciation of my effort, and after the obligatory 7% PayPal cut my net donations to date (spanning a bit more than one year) total to only $23.30. Yet I plod on, always trying hard to improve it and introduce new features and come up with better releases, while knowing full well that of the 2 to 3 people on average per day who will actually download it, right close to no one among them is willing to contribute donations to my effort. I'm always trying to answer questions as to its proper function, and listen to suggestions (both on this forum, and in private emails). And I'm quite often willing to run a forum members recipe through it and let him know my spreadsheets output advice. I've even endured some rather obvious (to me) spammers who rail on against my spreadsheet and its output by passing along clearly false and misleading information in regard to it, with their motives unknown to me, but each of such clearly painful none the less. With me it is a personal compulsion to better the product and bring happiness to the users who may find benefit in it that keeps me motivated, and allows me to endure such abuse. That I make roughly $23 per year for my effort indicates that my motivation to find and offer improvement is clearly not one of financial gain.

I commend you on giving away your efforts.

Now for what I am about to speak Lord forgive me.

Your development methods leave much to be desired. You seem to read a post about some topic that affects the mash pH, you then ask or surmise what would correct that deficiency in your spreadsheet and ask AJ Delange if you're correct or that he validates your assumption. You then "correct" the model in your spreadsheet to account for whatever it is believed to have needed changing and up the version number of your software - continuing the guess/correct cycle.

Guess/correct is not the best way to develop a mash model nor to update software.

 

[MSK_Chess]

great discussion guys, really.

The pH of a solution is a logarithmic measure of the freely available H+ions. The concentration of these ions affects the enzymes in various ways. A change in pH leads to changes in the charges on the enzyme due to the reaction of the H+ ions with the carboxyl or amino functional groups [cuny.edu].

The at high pH (low concentration of H+ in the solution> the carboxyl group disassociates

COOH → COO- + H+
This leaves a negative charge at the site of the carboxyl group and donates a proton* H+ to the solution. This reaction is reversed at low pH

At low pH (high concentration of H+ in the solution) the amino functional group binds a proton*

NH2 + H+ → NH3+
This results in a positive charge on the site of the amino group. A reaction that is reversed at high pH.

These pH dependent reactions determine the electric charges and as a result the shape of the enzyme and its ability to react with the substrate. As a result a pH exists at which the enzyme will be most efficient performing the reaction it was designed for. On either side of that optimum the effectiveness of the enzyme will decline until it is unable to function anymore.

The change in enzyme activity within 2-3 pH units to either side of the optimum is generally a reversible process [lsbu.ac.uk]. This means that no permanent damage is done to the enzyme. It also means that a suboptimal pH in mashing doesn't necessarily damage the enzymes and that the full enzymatic activity can be restored by adjusting the mash pH into the optimal range, except for the enzymes that have already been denatures. A more severe pH change 3+ units is likely to denature the enzyme due to high stress that the extreme change in the charges place on the structure of the enzyme. This basically makes the enzyme less stable and it denatures at a fairly high rate even below its critical temperature. In some cases strong acidity can also hydrolyze the peptide links (i.e. break the amino acid chain the makes up the enzyme).

When considering pH, it should be noted that the pH of a solution changes with temperature. The rate of change is dependent on the solution itself. For wort and mashes the actual pH is 0.35 units lower at 65 C (150F) than at room temperature 20 C (68 F). At 75 C it is 0.45 units lower [Briggs, 2004].

*I think the author means donate an electron, please correct me if I am wrong.
http://braukaiser.com/wiki/index.php/Enzymes

 

[hopjuice_71]

great discussion guys, really.

The pH of a solution is a logarithmic measure of the freely available H+ions. The concentration of these ions affects the enzymes in various ways. A change in pH leads to changes in the charges on the enzyme due to the reaction of the H+ ions with the carboxyl or amino functional groups [cuny.edu].

The at high pH (low concentration of H+ in the solution> the carboxyl group disassociates

COOH → COO- + H+
This leaves a negative charge at the site of the carboxyl group and donates a proton* H+ to the solution. This reaction is reversed at low pH

At low pH (high concentration of H+ in the solution) the amino functional group binds a proton*

NH2 + H+ → NH3+
This results in a positive charge on the site of the amino group. A reaction that is reversed at high pH.

These pH dependent reactions determine the electric charges and as a result the shape of the enzyme and its ability to react with the substrate. As a result a pH exists at which the enzyme will be most efficient performing the reaction it was designed for. On either side of that optimum the effectiveness of the enzyme will decline until it is unable to function anymore.

The change in enzyme activity within 2-3 pH units to either side of the optimum is generally a reversible process [lsbu.ac.uk]. This means that no permanent damage is done to the enzyme. It also means that a suboptimal pH in mashing doesn't necessarily damage the enzymes and that the full enzymatic activity can be restored by adjusting the mash pH into the optimal range, except for the enzymes that have already been denatures. A more severe pH change 3+ units is likely to denature the enzyme due to high stress that the extreme change in the charges place on the structure of the enzyme. This basically makes the enzyme less stable and it denatures at a fairly high rate even below its critical temperature. In some cases strong acidity can also hydrolyze the peptide links (i.e. break the amino acid chain the makes up the enzyme).

When considering pH, it should be noted that the pH of a solution changes with temperature. The rate of change is dependent on the solution itself. For wort and mashes the actual pH is 0.35 units lower at 65 C (150F) than at room temperature 20 C (68 F). At 75 C it is 0.45 units lower [Briggs, 2004].

*I think the author means donate an electron, please correct me if I am wrong.

Thanks for this. Just to amend it a bit *warning science ahead*...

Barley amylases use a double displacement catalytic mechanism. The carboxylate side chain of an amino acid in the enzyme active site acts as a general acid/base in catalysis, another different carboxylate side chain of an amino acid in the active acts as a nucleophile (there are no amino groups involved in catalysis by amylases). The protonation states of the amino acids is key to their participation in catalysis - the acid/base must start the cycle protonated while the nucleophile must start deprotonated. The ascending limb of a pH profile (lower pH side of the maximum), like that posted by MSK_Chess, corresponds to the protonation state of the nucleophile (as defined by its pKa, which is in turn defined by its particular environment in the enzyme). Correspondingly, the descending limb (high pH side of the maximum) represents the protonation state of the acid/base, again defined by its pKa. In fact, the pKas of catalytic residues can be determined by the inflection points of the ascending and descending limbs of pH profiles. A pH below the pKa of the nucleophile or above the pKa of the acid/base and the enzyme is inactive - but not necessarily denatured (most proteins are quite stable between pHs of 3 and 9, regardless of their optimum operating pH). It turns out in the barley amylases, and in the a-glucosidase/amylase family in general, the pKas of the catalytic residues are quite well separated, often by several pH units as in the barley enzymes, giving broad pH profiles with no real maximum.

 

[ajdelange]

I want them doing what they have evolved to do, which is both.

If I have a tree I want cut down I call Kenny. Kenny is very good as a woodsman and he is also perfectly capable of walking here. But I don't want him to. Not only will the job get started faster if he drives but he will have more energy to devote to cutting the tree if he does.

And for the record, I'm not saying I don't pay attention to pH. I just don't worry about it much. The title of the thread asking the question if how important is pH adjustment, my answer would be: "somewhat." It is important enough to know the parameters and get in the ballpark. Not important enough to lose sleep over. I'm way more concerned with yeast health, sanitation, cold side oxidation, water mineral profile, ingredient quality and good old recipe formulation. Cheers.

I have no problem with that approach. Now I will admit that I do lose sleep over mash pH but not because I am worried about my mash pH but rather because I am trying to think of some better way to estimate it or measure the things I need to know to make those estimates. It's just another one of the multiple aspects of brewing that one can find himself interested in and choose to devote his attentions to.

I sort of stumbled onto the beneficial aspects of mash pH control but when I tasted how much better that first pH controlled beer was than any other I had ever brewed I was sold on it. So my perspective on it was derived from that experience and the engineer's natural inclination to want to take the clock apart to see how it works.

 

[ajdelange]

Hopjuice and Chess: Interesting posts but bunk! Enzyme activity is constant until pH exceeds 6.5. That was clearly stated in No. 35.

 

[ajdelange]

At low pH (high concentration of H+ in the solution) the amino functional group binds a proton*
*I think the author means donate an electron, please correct me if I am wrong.

He's right. Look at the dissociation equation

RCOOH <---> H+ + RCOO-

Consider Chatellier's Principle. As you lower pH you are increasing the concentration of H+ and this pushes the reaction to the left. Protons in solution are taken up by RCOO- ions thus forming the acid RCOOH. This is not limited to amino acids nor to the side chains of the enzyme proteins nor to any other proteins in the mash. It applies to all acids in the mash.Just to pick an acid consider succinic acid. It has two pK's 4.2 and 5.6. If the malt has a DI pH of 5.7 and has been mashed in DI water then the mash pH will be 5.7 and the wort will contain a tiny bit of H2Suc, more HSuc- and lots more Suc--. If some lactic acid is added supplying protons the following reactions will occur
Suc-- + H+ --> HSuc-
HSuc- + H+ --> H2Suc

All three succinate species will be present but they will be redistributed in such a way that the overall charge on them is decreased (made more positive) by exactly the number of protons absorbed.

 

[MSK_Chess]

LOL you guys are 2 funny. Hopjuice its a bit beyond my understanding at present even after reading it numerous times, clearly I am way out of my depth but I really do appreciate the effort. I am familiar with the idea of 'donating' electrons, but protons, I have never even come across! so far at least.

 

[MSK_Chess]

He's right. Look at the dissociation equation

RCOOH <---> H+ + RCOO-

Consider Chatellier's Principle. As you lower pH you are increasing the concentration of H+ and this pushes the reaction to the left. Protons in solution are taken up by RCOO- ions thus forming the acid RCOOH.

[/QUOTE]
Hi aj its a concept I am completely unfamiliar with and even if you explained it to me for a thousand years I don't have enough understanding to grasp it, cations and anions I am familiar with and I thought this was what the author was referring to.

 

[ajdelange]

Donating and picking up electrons is usually in the province of redox reactions whereas proton exchange is in that of acid/base reactions.

However we can define a base (Lewis) as an electron pair donor. One of the criticisms of this approach is that it turns acid/base reactions into redox reactions.

I'll bet you can understand proton exchange. First off, what is a proton? It is an atomic particle with the same charge as an electron but with a positive charge of the same magnitude as the electron's. A hydrogen atom is made up of one proton and one electron. In water two hydrogens come into the vicinity of an oxygen atom. Oxygen is more electron hungry that hydrogen so the oxygen pulls the hydrogen atoms' electrons close to it leaving it with a net negative charge and the hydrogen atoms with a net positive one. They are attracted, therefore, to the oxygen and the molecule stays intact. But if something comes along to disturb this tranquil scene one of the hydrogen atoms can get knocked off. It does not take its electron with it, however. The oxygen holds on to it. So we get H2O <--> H+ + OH-; the dissociation of water, Now that H+ is just a hydrogen atom minus its electron IOW a proton.

Where does that proton go? Often it's straight to another water molecule so that the real reaction is H2O + H2O <--> H3O+ + OH-. Other times it goes to another base such as a bicarbonate or succinate ion. Does that help at all?

 

[MSK_Chess]

ok, well that helps, I was unaware, I'll come back in about a thousand years and we shall talk then!

 

[Silver_Is_Money]

I commend you on giving away your efforts.

Now for what I am about to speak Lord forgive me.

Your development methods leave much to be desired. You seem to read a post about some topic that affects the mash pH, you then ask or surmise what would correct that deficiency in your spreadsheet and ask AJ Delange if you're correct or that he validates your assumption. You then "correct" the model in your spreadsheet to account for whatever it is believed to have needed changing and up the version number of your software - continuing the guess/correct cycle.

Guess/correct is not the best way to develop a mash model nor to update software.

There is much truth in this, but the full truth is that I have mainly changed the means by which my software handles the deep roast end of the SRM spectrum, wherein the light to mid SRM's have not been radically altered. I do not have experience in brewing deep roast beers, and I have vacillated between a historical need to have up to 200 ppm alkalinity and A.J.'s contention that such is nowhere near the case in the real world. I've hitched my wagon in regard to robustly dark brews to enough losers that I finally decided to hitch it to a winner.

Along the way I have demonstrated that other of such software as mine has (for one particular recipe I've plugged into all of them) spanned from a need for a bit of acidity all the way to a need for 16.5 grams of baking soda, so my dilemma here is not solely my own. I just happen to be very public and honest and open as to my doings and alterations with regard to my software, and as to my reasoning for same. Others have over the years made radical changes, but the best you can expect to hear from them is generally that a new version is available. And often enough, you don't even hear that.

 

[hopjuice_71]

Hopjuice and Chess: Interesting posts but bunk! Enzyme activity is constant until pH exceeds 6.5. That was clearly stated in No. 35.

To be honest, I interpreted his pH 6.5 comment as referring to the pH above which amylase activity falls off significantly, which would be roughly consistent with the pH profiles of these enzymes. But perhaps I missed something?

 

[ajdelange]

Actually, sixhotdogneck is right here. I am part of that medical (research) community. I also research enzymes that convert polysaccharides, very much like the barley amylases. Enzymes very often have quite broad pH profiles, including those that are medically relevant. Scientists generally pick an estimated "peak" because it simplifies things for the end user; however, enzymes will typically operate quite well over sometimes very large pH ranges (depending on the catalytic mechanism they use). Think about it, an enzyme that has really tight operational parameters will not be a successful tool for an organism in a changing environment. This applies to the internal workings of humans as well.

Specific to the barley amylases, it is quite well documented in the primary literature that they have >90% activity over a pH range of ~4.5-6.5 (some of those authors are colleagues of mine). But, someone, sometime, was forced to pick a "peak," which is really just the centre point of a broad plateau in the pH profile. This pH optimum has persisted in brewing, maybe because on a massive commercial scale a 2% increase in activity translates to cost savings.

Think about what you are saying. There are enzymes that exhibit broad activity peaks of course. Apparently papain is flat over entire range of biological possibility. But hotdog's statement was that enzyme activity is constant until pH 6.5 is reached. How about pH 4. That's below 6.5. Is the activity of alpha amylase the same at 4 as it is at 6? And how about beta amylase? The guys that sell it say its range of peak activity is 4 - 5.5. Is it's activity at 5 the same at 5 as it is at 6.5. And how about beta glucanase. The Enzyme Education Institute says its maximum activity occurs between 3.5 - 6. Is it's activity at 6.5 the same as 5? And what about the myriad of other enzymes in barley malts that catalyze the reactions that produce the flavor aroma and body characteristics we seek? Are their activities flat over the range of possible mash pHs? Clearly no or mashing in a certain range would not result in better tasting beers.

Perhaps because of commercial brewing practices where a 2% yield in extract may have significant impact on the bottom line everyone thinks the goal of pH control is better extract. That isn't the only goal. Better tasting beer is. It is recognized that the pH's goals stated in the literature represent a compromise as we haven't much choice but it's also recognized that best extract yield isn't the only thing coupled to profits. Beer quality has something to do with it.

 

[hopjuice_71]

LOL you guys are 2 funny. Hopjuice its a bit beyond my understanding at present even after reading it numerous times, clearly I am way out of my depth but I really do appreciate the effort. I am familiar with the idea of 'donating' electrons, but protons, I have never even come across! so far at least.

Well, you are not off course here. There is a proton inventory but there is also bonds being broken and formed, which involves a reshuffling of electrons. When we write out the catalytic mechanisms we actually track the electrons with teeny little arrows.

 

[sixhotdogneck]

To be honest, I interpreted his pH 6.5 comment as referring to the pH above which amylase activity falls off significantly

Yes.

 

[ajdelange]

Truth generally stands on its own.

No, it doesn't. It has to be discovered and that's what we try to do here.

I have no need to engage in vitriolic discussions.

We are trying to get you away from vitriolic comments to support your controversial assumptions. You have some reason for thinking that higher pH which results in more dissociation of phenols leading them to be more polar in character is not related to their solubility in a polar solvent: water. That's not generally accepted as true. If you have some reasons for thinking that it is true you should not be afraid to state what they are. For example you might have done some experiments that contradict the conventional understanding. No vitriol needed (unless you used it in your experiments).

Try it for yourself and report back.

Reporting back for the fourth (or is it fifth time):
Controlling mash pH improves beer! It's done so for me. It's done do for others here and it's done so for breweries the world around. Again, in the hopes you'll read it this time: why would a world class brewery with very low alkalinity water acidify its mash if there were no benefit?