SRM & Mash pH; Sauermalz?

[user 246304]

Hi guys,

This sort of spans a couple boards, so didn't want to make 2 threads.

I'm reading through Palmer's/Kaminski's Water again, and, naturally, reading through threads here with particular attention to AJ Delange's and Martin Brungard's comments. Infinite, this brewing universe.

I wasn't aware of AJ's views on the weak, if any, correlation between the use of colored malts and mash acidity (I hope I even read that right). So he does caution about using Palmer's calc for working out dark beers. Does anyone, perhaps AJ? - have a link or links to more material discussing this? I've always seen it as a religion, mostly because I've dealt with alkaline "given" waters where I've lived. Dark beer? Fuggedaboutit, no alkaline stress.

Secondly, and I admit this belongs more in the ingredients section, but I'm also growing more curious about AJ's use of sauermalz. I've never used it, have always used (added) acids and salts for adjusting water (even now I have a 37% HCL I'm diluting to 10%, to experiment).

My hesitation in the past with adding in a sauermalz (well, also an acid rest, to be truthful, though I know that's completely illogical) of some type is a concern of its impact on flavor. Basically, I couldn't see a British grist universe containing MO, let's say, and sauermalz. Is there a flavor or other quality component to sauermalz, aside from acid, that you have to keep in mind when using it?

Thanks.

 

[Silver_Is_Money]

The lactic acid flavor detection threshold is higher than commonly accepted. See this experiment by Kai Troester.

http://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment

Conclusion
It was surprisingly difficult for panelists to pick out beers that had lactate added even at levels that correspond to an equivalent acidulated malt use of 13% and higher. Note that the acidity of the lactic acid was neutralized with slaked lime. A general recommendation for home brewers is to keep the use of acidulated malt below 5%, which corresponds to a level of 264 mg/l added lactate in a 12 Plato beer with 85% efficiency into kettle. Many of the panelists were not able to pick up the added lactate at a level of about 400 mg/l which corresponds to about 7.5% acidulated malt. Based on that we can safely say that even 8% acidulated malt won't ruin a beer if that amount is needed to counteract water alkalinity.

Quoting Kai Troester above

I recently brewed a 5.6 gallon (60 x 12 oz bottle) yielding batch of 13.1 Plato Bohemian Pilsner (about 6.1 gallons initially went to the fermenter, including trub, which I made no effort to separate) and I added 6 ounces of Weyermann's acidulated malt (the nominal equivalent of ~4.85 mL of 88% lactic acid) to the grist. I can't detect its presence at all, but admittedly it was only ~3.25% of the grist by weight.

 

[user 246304]

Great, thanks Silver, I'll check it out. Always intrigued about running a lactic-acid mash in combo with a 3-decoction mash on under-modified malt - the whole Greg Noonan shebang. Might be fun to make this a winter experiment.

Thanks for the link, and your data point.

 

[mabrungard]

Looking at the passage by Kai, I can tell you that 4.85 ml of 88% lactic in 5+ gallons is nowhere near the flavor threshold for lactic acid. Its more like 1.3 to 1.5 ml/gal when most tasters will pick it up.

For most brewers, lactic acid or acid malt use is fine for all brewing. Its mainly brewers with fairly high alkalinity that need to employ other acids in order to avoid the lactic flavor.

By the way, lactate is a yeast nutrient.

 

[Silver_Is_Money]

Looking at the passage by Kai, I can tell you that 4.85 ml of 88% lactic in 5+ gallons is nowhere near the flavor threshold for lactic acid. Its more like 1.3 to 1.5 ml/gal when most tasters will pick it up.

Agreed in full, and that is why I intentionally included within the post I made above the carefully worded disclaimer that my acidulated malt addition was admittedly only 3.25% of the grist weight.

 

[user 246304]

OK, thank you both. I'm trying to find a way to employ my water, without needing to dilute it so much that I might as well go all the way (though at 3:1, admittedly feel better about some trace elements like the Zn you mentioned, Martin). We're really high in HCO3, 364, so perhaps it's ludicrous for me to think of treating with acid and salts only (I am still intrigued by a traditional separate mash development, for lactic). As I mentioned, I have available probably more HCL than I can use over the next decade, and like the added bonus of some "free" CL-.

That's great info on the taste threshold of lactic, however, Martin; very much appreciated. I used to use both lactic and phosphoric with no ill effects whatsoever, so I don't know what I'm worrying about with some sauermaltz. Will give it a try.

Thank you again, guys, really helpful.

 

[ajdelange]

Gadjobrinus said:
I wasn't aware of AJ's views on the weak, if any, correlation between the use of colored malts and mash acidity (I hope I even read that right). So he does caution about using Palmer's calc for working out dark beers. Does anyone, perhaps AJ? - have a link or links to more material discussing this? I've always seen it as a religion, mostly because I've dealt with alkaline "given" waters where I've lived. Dark beer? Fuggedaboutit, no alkaline stress.

Replied to this Friday (I think it was) and post is 'awaiting moderator approval' whereas posts I've made more recently have gone right through so I've concluded that my previous post is going to stay 'awaiting moderator approval' and am re-posting here.


I wanted to reply to this earlier but priority has been getting my walk in compressor going again. Suction service valve is leaking and R22 is now $30 a pound! Whoever put that valve in that machine really, really didn't want it ever taken out. Looked like a piece of cake: RotoLock on the compressor side and flare on the line side. No brazing! But I had to de-braze to get the thing out to where I could put big enough wrenches on it to turn that flare nut. After all that the nearest replacement is in a warehouse in Delaware. OK. This has little to do with color models but I feel better.

The problem is not that the correlations between color and malt properties are not good. The problem is that good correlation isn't good enough. It has to be very good correlation. The properties we are interested in here are the parameters of the malt titration curves. DI mash pH and three coefficients, the first of which is the slope of the curve at the DI mash pH and the other two of which are related to the second and third derivatives of the curve are really needed to characterize a malt. Most programs use estimates of DI mash pH and the first term only so even were the color models accurate an error is introduced by most programs because they ignore the no linearity.

The pioneer in this was Kai Troester and, AFAIK, the data he has posted on his web site is the only comprehensive set involving several malts of different types. So i looked at his data (on his site). It is clear from his data, and he recognizes this, that the black malts are an exception and need to be treated separately so taking those out of the data set I did a fit to the DI mash pH vs EBC data which remained. Pearson's r was -0.88. I think everyone will agree that that is a pretty good fit and definitely shows that there is a relationship betweem malt color and its DI mash pH. But (-0.88)^2 = 0.78 and that means that the model (pHDI = 5.642 - 0.0059588*EBC) only explains 78% of the variation in mash DI pH and that the remaining 22% is due to 'noise' (the inadequacies of the model). For this particular data set the estimated rms error in the predicted DI pH is ±0.18 pH. That's not very good and as pHDI for the base malt is a major factor in the prediction of mash pH and casts definite suspicion on the claims of 'spot on' prediction accuracy by some users.

 

[user 246304]

AJ, my sympathies on your compressor. That sounds like one ugly set of hours, and it also sounds like it ain't over by far. Sorry - rarely been there, but when I have (e.g., my restaurant's freezers - all of them - died, and we were looking at some serious inventory loss. Shhh, long time ago now....but it was close to 0F outside and, um, we found some temporary storage). Hope it improves from here.

Thank you on the rundown on the SRM issue. Fascinating, though it frustrates me I need to grab my stats text again to get even these elementary data points more than conceptually. But I get it enough. Believe it or not, I pursued comparative Western European national political development at Berkeley, all qualitative stuff, words and lots of them. 20 years later when our restaurant went under I gave a thought to going back and finishing my PhD. The world had moved in those 20 years, lol, and history was now all quantitative, literally. So I went to U of M for a summer to get the first tastes of what was needed. Did fine, but it's all water through a sieve with time (no pun, lol).

I'm re-reading the Water book with the intent to truly get it down. Kai's site too. I wish, of all things (and I'm being serious), that you had a book, AJ. When you read from several sources, each seems compelling, and you don't have the tools to evaluate their authoritativeness well..I at least can find myself running peripatetically after each line of thinking.

 

[ajdelange]

Perhaps this diagram will help. In it we assume there is something we want to know (DI mash pH) for which we have values for several malt colors and we want to know what that DI mash pH is at any malt color, not just the one's we have the data on. With the data we have we can see if there is a simple model which describes the behaviour of DI mash pH with respect to color. In this sketch there is such a model and it is DI pH = 0.94*color and that relationship is represented by the straight line. But as you can see the straight line is not a perfect model. We actually find that few malt color/mash pH pairs lie on the line (each malt is represented by a circle). The upper curve shows the distance of the actual malt's DI pH from the line. Thus no malt is represented by DI pH = 0.94 exactly but only approximately so. As the upper plot shows sometimes the difference is very small and sometimes it is quite large.

The data in this plot were hoked up to represent the same quality of fit as Kai's actual DI mash pH i.e a value of r = 0.88 which might at first blush seem a pretty good fit (perfect is r = 1). But as the data show (more points here help to illustrate this) it isn't.

 

[user 246304]

Wow, extraordinary. Yes, I see it, AJ, and thank you for laying it out for this "statistics for dummies" victim (I got letters of recommendation from both the U of M stats guy, and quantitative history guy, to head back to Berkeley, if you can believe it. Just licking my wounded pride, I think.). I actually flipped through Appendix B of the water book last night and saw your acidification charts there, too. I am committed to learning this, and am really grateful to you.

So if the answer is, "read the Water book; read my articles; read Kai" please don't hesitate. As I just exchanged with Silver, what is the basic mechanism, then, for stouts, porters, and the like, to work so easily with highly carbonate water without acidification, if not color? He mentions his 2-row is more acidic than his vienna, as an example. I would have thought the opposite. Is this simply the phosphate reaction (or is that the erroneous SRM connection, that dark malts are higher in phosphates, thus bring on more acidification and drop the pH?).

 

[ajdelange]

The answer is "Measure the DI mash pH of each malt you intend to use. Then titrate in order come up with the three coefficents from which a Taylor series expansion can be done that gives the number of mEq of acid or base required to move a kg of the malt from the mash DI pH to an arbitrary pH:

mEq/kg = a1*(pH - pHDI) +a2*(pH - pHDI)^2 +a3*(pH - pHDI)^3

Clearly this is impractical unless the maltsters decide to do it and they either think it's too much work or don't see how doing it will sell more malt. Thus second best is to use the color based calculations (they aren't that bad in general), design your grist and then check with a test mash.

 

[user 246304]

I don't yet get the math behind it, but again conceptually I'm getting it so thanks again, AJ. I just came across your discussion of titrating and the 3 coefficients. Might have been here, might have been in that Appendix? Can't recall. But thanks.

On the "sort of OK" aspect of SRM, thanks for that too. I just went back to a Bru'n spreadsheet and saw Martin seems to have modeled the issue slightly differently than in past associations of color and RA (though I've been lurking and reading through your posts - and saw someone brought up RA as an older issue, I believe? I know Cire here, himself, uses TA and not RA in his work. So much to learn).

 

[user 246304]

AJ, as I said, exchanging with Silver. I'd like to ask here, if I could.

It feels like software modeling is undependable. I'd like to learn the basics. I know you recommended a non-brewing water book, that covers some chemistry. Would you: (1) Recommend the Palmer/Kaminski for fundamentals; and (2) Forget any software, start from simple - perhaps the primer - and rely on a good pH meter, instead?

 

[mabrungard]

It feels like software modeling is undependable.

That is true, if you are relying on a prediction being within a couple of hundreths. However, if you are OK with being something like a tenth off of prediction and you don't want to do test mashes and a bunch of other preliminary tests prior to actually brewing, then software can be pretty good!

But, don't end your quest for more knowledge.

 

[user 246304]

Thank you Martin. I understand, and appreciate the comment. I think you said the two main concerns I have - I do want to get brewing, but it drives me nuts to know so little of the science behind water. I've spent a decent time with hops and malt, some less on yeast, but comparatively speaking, so little on water. So yes, I want to learn it.

Edit: I stepped in it and truly didn't mean to, Martin. Seems to be a gift I have here. Driven by the desire to learn the science, as well as the desire, as you rightly say, to get to it with some useful tools. Add to that (if you see the thread on RO water and "slack" flavor), I came from a lot of pleasurable years with well water, boiling, some salts, and empirical additions of phosphoric to the sparge. Targets were nailed, with virtually no outliers, and it was great.

 

[ajdelange]

A model is a model. Some models are clearly better representations of the real world than others but they are still models. Beyond the quality of the model itself we have to consider that the best model fed bad data will result in bad answers. The Taylor series expansion model coupled with the charge computations are robust but if you put bad DI mash pH's or bad a1, a2 and a3 into it you will get no better an answer than if you use one of the lest robust models.

That said, any model, even an approximate one, can teach you a lot. If the model says that the addition of an Oz of sauermalz will lower your mash pH by 0.2, even though in the actual mash tun it turns out to lower it by .15 (or .25) you have still learned that sauermalz is very powerful in controlling mash pH compared to 10L crystal, for example. So any of the spreadsheets/calculators are valuable learning tools. It is often interesting to put the same information into each of several of them and look at the differences in their predictions. They may produce different exact numbers but they should all produce the same general effect as a result of a stimulus (e.g. adding a little sauermalz lowers pH quite a bit).

I think the water book you may be referring to is Morgan and Stumm's "Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters". That is certainly an excellent reference. Everything you need to know about water itself is in there. But this is not a beginner's text. Before approaching it you need to be fairly well versed in, as the title suggest, the science behind chemical equilibrium. This isn't dark art or anything like that but their approach assumes that you have some facility with it.

I would recommend the Pamer/Kaminski book. It's got as much of the basic science in it as I could convince John to include but that is not all of it and he had, at the time, decided that the key to understanding all this is RA and while RA is a part of the problem (the sum of a couple or terms in the proton deficit budget) it is not the whole problem and it usually does not need to be considered as a separate entity. The RA theme tends to distract from what turned out to be the important stuff. I say 'turned out' because Q(pH), as calculated for the acids and measured for the malts was at, the time of publication, a desperation measure to quickly get John a chapter on mash pH calculation/control as the project was substantially behind schedule. The material at that time was ready for a paper (which I did subsequently publish) perhaps but not for a book. So that material isn't presented in the book as well as we would be able to do it today.

Probably the most concise statement of the approach is in a set of slides I put together for the MBAA regional conference subsequent to the publication of the paper. They are at http://www.wetnewf.org/pdfs/Brewing_articles/MBAA_FREDERIC.pptx

 

[bitteritdown]

Acidulated malt (Weyermann Sauermalz) was also included
in the titration tests. One titration test determined a specific
acidity of 315 mEq·kg-1 while another test determined 358
mEq·kg-1. This corresponds to a lactic acid content of 2.85
% and 3.22 % by weight and matches Weyermann's
specification of ~ 3% (w/w)

You may be interested in reading about the SRM model and how it was developed: Effect of Water and Grist on mash pH

It would be interesting to know the models each spreadsheet uses:

EZ Water (?)
Bru N Water (?)
Brewers Friend (?)
Mash Made Easy (?)
NUBWS (Nearly Universal Brewing Water Spreadsheet) (?)
Palmers Water Spreadsheet (?)
BeerSmith (?)
Mph Water Calculator (?)

 

[user 246304]

A model is a model. Some models are clearly better representations of the real world than others but they are still models. Beyond the quality of the model itself we have to consider that the best model fed bad data will result in bad answers. The Taylor series expansion model coupled with the charge computations are robust but if you put bad DI mash pH's or bad a1, a2 and a3 into it you will get no better an answer than if you use one of the lest robust models.

That said, any model, even an approximate one, can teach you a lot. If the model says that the addition of an Oz of sauermalz will lower your mash pH by 0.2, even though in the actual mash tun it turns out to lower it by .15 (or .25) you have still learned that sauermalz is very powerful in controlling mash pH compared to 10L crystal, for example. So any of the spreadsheets/calculators are valuable learning tools. It is often interesting to put the same information into each of several of them and look at the differences in their predictions. They may produce different exact numbers but they should all produce the same general effect as a result of a stimulus (e.g. adding a little sauermalz lowers pH quite a bit).

I think the water book you may be referring to is Morgan and Stumm's "Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters". That is certainly an excellent reference. Everything you need to know about water itself is in there. But this is not a beginner's text. Before approaching it you need to be fairly well versed in, as the title suggest, the science behind chemical equilibrium. This isn't dark art or anything like that but their approach assumes that you have some facility with it.

I would recommend the Pamer/Kaminski book. It's got as much of the basic science in it as I could convince John to include but that is not all of it and he had, at the time, decided that the key to understanding all this is RA and while RA is a part of the problem (the sum of a couple or terms in the proton deficit budget) it is not the whole problem and it usually does not need to be considered as a separate entity. The RA theme tends to distract from what turned out to be the important stuff. I say 'turned out' because Q(pH), as calculated for the acids and measured for the malts was at, the time of publication, a desperation measure to quickly get John a chapter on mash pH calculation/control as the project was substantially behind schedule. The material at that time was ready for a paper (which I did subsequently publish) perhaps but not for a book. So that material isn't presented in the book as well as we would be able to do it today.

Probably the most concise statement of the approach is in a set of slides I put together for the MBAA regional conference subsequent to the publication of the paper. They are at http://www.wetnewf.org/pdfs/Brewing_articles/MBAA_FREDERIC.pptx

AJ, man, I'm not saying this for any effect other than an expression of thanks, sincerely. I re-read your foreword often (in fact, on too many "re-reads" of the Water book - I need to keep going further than your foreword, lol), and your eloquence in bringing the science down so one can at least gain a foothold is a gift that not everyone can do. Thank you. I don't know why, but I literally just thought of an old friend, a healthcare economist, whose PhD was cutting edge at the time, and that was in doing some sort of computer modeling that astounded me, though I knew I'd never know what he knew. At Berkeley, I had a guy next door working on the physics of two dimensional space; my other neighbor was in AI. In the mid '80's, so you know the state at that point. Meanwhile, I felt almost embarrassed to be living in this grad (married) housing. I moved through about 600 pages a day, tore them apart, worked on alternate theories using a lot more words. But the wiring to easily come to math was never mine. So for those like me, yes, thanks.

And yes, that is the book. I've had it on the Amazon cart. Where it appears it needs to stay for awhile, till I get a better handle on things. Interestingly, I think I actually got to it from the Palmer/Kaminski book, I've also had your 2004 paper on Alkalinity, Hardness, RA and Malt Phosphate up for awhile, and see that you cite Stumm in there as well. Between you and your colleagues, I think I'll be busy for awhile.

 

[user 246304]

You may be interested in reading about the SRM model and how it was developed: Effect of Water and Grist on mash pH

It would be interesting to know the models each spreadsheet uses:

EZ Water (?)
Bru N Water (?)
Brewers Friend (?)
Mash Made Easy (?)
NUBWS (Nearly Universal Brewing Water Spreadsheet) (?)
Palmers Water Spreadsheet (?)
BeerSmith (?)
Mph Water Calculator (?)

Thanks Bitter, I'll check it out.

 

[ajdelange]

It would be interesting to know the models each spreadsheet uses:

NUBWS (Nearly Universal Brewing Water Spreadsheet) (?)

The NUBWS that comes up if you click that link does not include any mash pH prediction. That capability has been added to it but not in that version. I decided years ago that NUBWS had grown to the point, without any attention to the user interface, to the point that it would be of no practical use to home brewers because the cost of having it do so much is that it is terribly complex.

That said, FWIW, the mash prediction algorithm the current version contains is based on calculation of Q(pH) for acids and malts as described in my previous post and in the MBAA slides I referenced. That algorithm is so simple that someone with those slides should be able to put together a spreadsheet that predicts mash pH quite easily and some have done so.