Bru'n water help

[millsbrew]

I've just "upgraded" to an e-HERMS setup and my last few batches have been very inconsistent. My last batch I had horrible efficiency (67%), the one prior was 86%. I have been using RO water for a few years, but only recently has my efficiency been all over the place. So I bit the bullet and got a Milwaukee 102 and an updated Ward Labs report. My water pH per Ward was 6.5ph, but per the 102 it is 5.0. I realize RO water is difficult to get a pH reading on due to lack of ions. I have tried entering both values into Bru'n water, but neither seems to change the recommended acid addition. The 67% eff batch, I had a calculated pH of 5.37 with .8ml of 88% lactic acid added. I only added .5ml, and my pH was still 4.98. I went into Bru'n water to change the pH value on the Water Report tab, but it still recommended .8ml lactic and had a sugg value of 5.37. Aka - No change.

Any input is greatly appreciated.

 

[mabrungard]

Water pH has virtually no effect on mash pH. Don't worry about what the pH meter is reading in RO water. That pH value on the Water Report tab is for calculating the concentrations of bicarb or carbonate when you are converting an alkalinity value. It has nothing to do with the rest of the program.

That 4.98 pH, was the wort recirculated through the grain bed completely? Did you add that acid dose to the water before doughing in or after?

 

[ajdelange]

The required acid addition (if any) does not depend much on the pH of the water but rather mainly on its alkalinity. As RO water has virtually 0 alkalinity it does not matter what its pH is. The required acid the program calculates when alkalinity is 0 is not for the water: it is for the malt.

 

[millsbrew]

The grain bill was 5# 2row and 3.5# wheat with 0.75# flaked wheat. I added the acid at 5mins into mash (forgot to do it before dough-in). Then I added flaked at 20 mins and turned on my recirculation. Is there anything I should change on the malt bill tab besides base/crystal/acid/roast?? I usually use BeerSmith for my SRM.

 

[mabrungard]

You have no hope of having had the wort and mash mixed very well. Your pH reading is a symptom of that. ALWAYS add and mix all minerals and acids to the water PRIOR to adding the grain.

I've sometimes forgotten a mineral or acid addition when brewing on my RIMS and it can take many minutes of circulation to reestablish the equilibrium pH. Others have checked pH at various points within a grist when an acid addition is mixed vigorously into the mash by hand and they found pH varied markedly. It is extremely difficult to mix a mash by hand and achieve homogeneity. There is a better chance when you are moving the wort instead of the solids.

 

[ajdelange]

What was the measured pH of the mash? At first blush it looks as if 0.8 mL is way too little lactic acid. Take the wheat alone. You have about 1.5 kg of that, it's pHDI is typically around 6 and its buffering about 45 mEq/kg•pH. Shooting for a mash pH of 5.4 means a proton deficit of (6 - 5.4)*1.5*45 = 40.5 mEq. As 88% lactic is about 11.4 N at this pH it is clear that about 3.5 mL of lactic would be needed to handle the wheat by itself. I calculate (without, admittedly, knowing any of the details of the malts) that about 7 mL of acid would be needed for pH ~ 5.4.

 

[millsbrew]

Measured Mash pH was 4.98. This was 20 mins into Mash. So I would think 15mins after lactic addition should have been enough to get a proper measurement. I only added CaCl2 and CaSO4 to Mash (besides the lactic). Edit: I typically let my mash sit for the first 20 mins before recirculating.

 

[Silver_Is_Money]

Regarding the mash that metered at pH 4.98, what was your entire grist bill, including mash water mineralization and acidification quantities? What quantity of mash water was used? Did you build the strike water from RO?

Martin likely hit the nail on the head, in that you most likely did not get sufficient mixing before pulling your pH sample.

Was the pH sample properly cooled to nominal room temperature? When hot (at mash temp.) the pH will measure about 0.25 to perhaps 0.35 lower than actual.

 

[ajdelange]

4.98 does not compute. As this is apparently your first assay into pH measurement it is quite possible that the reading is in error and the mixing hypothesis that has been presented above may well be the source of that error but check the pH cal sticky for tips on how to use a meter.

 

[millsbrew]

Thanks. I will try the same recipe again and report back. But I find my pH is often considerably lower than estimated. Shouldn't 20 mins be a significant time to wait especially considering I am not adding any buffers like lime or chalk???

 

[ajdelange]

No, not really. Measurements on a single malt with distilled water show that the measured pH migrates for up to half an hour. Though most of the change takes place in the first 5 or 10 minutes it is not unusual to observe some creep even 25 minutes in. It just takes some time for the water to penetrate the grist particles and dissolve the acids and bases (some of which are parts of proteins) they contain.

 

[mabrungard]

Thanks. I will try the same recipe again and report back. But I find my pH is often considerably lower than estimated. Shouldn't 20 mins be a significant time to wait especially considering I am not adding any buffers like lime or chalk???

I consistently find that pH does vary during a mash. However, the direction of pH change is dependent upon the initial pH.

When your initial pH in a well-mixed mash is less than 5.4, I consistently see the pH rise during the mash to be closer to 5.4. If the pH starts higher than 5.4, the pH tends to fall during the mash. There is some sort of buffering that is acting in the mash that is not well understood, but its effects are consistent.

I no longer worry if I measure an initial pH that is not at the pH I've targeted with my water adjustments. I continue to monitor the pH and have consistently seen the pH move as pointed out above.

 

[ajdelange]

I consistently find that pH does vary during a mash. However, the direction of pH change is dependent upon the initial pH.

If the initial pH is higher than the equilibrium pH the pH will lower over time and conversely.

When your initial pH in a well-mixed mash is less than 5.4, I consistently see the pH rise during the mash to be closer to 5.4. If the pH starts higher than 5.4, the pH tends to fall during the mash.

If the pH moves towards 5.4 then 5.4 is obviously the equilibrium pH which means that the mash has been, intentionally or otherwise, designed for 5.4. If the equilibrium pH is 5.5 then observed pH will migrate towards 5.5 and a brewer producing beers designed for 5.5 will see migration towards that level. There is nothing magical about 5.4. The equilibrium pH depends on what is in the water and the malts selected and the brewer can control the end value pH by manipulation of malt types and the addition of acids. If I brew a beer with equilibrium pH 5.5 (which, we hope, is also the target pH) using acid or acid malt the initial pH will be low (sometimes startlingly so) and move fairly rapidly upward settling, after half an hour or so, at 5.5. This is because the first thing the pH electrode sees is the water which contains the acid I added or which has dissolved from the surface of the sauermalz. pH migrates up as proton absorbing entities in the malt migrate into the solution and are seen by the pH electrode.

If I brew a beer with equilibrium pH 5.5 using baking soda then the initial pH observed by the meter will be that of a baking soda solution (8.3) and only as the malts' proton releasing components enter the solution will the pH start to fall and eventually settle at 5.5.

pH 5.4 will be passed on the way up in the first case. pH 5.4 will never be reached in the second.

There is some sort of buffering that is acting in the mash that is not well understood, but its effects are consistent.

It is quite well understood. The mash pH settles at the value where the sum of all the protons released by the acidic components of mash exactly balance the sum of all the protons absorbed by the basic components of the mash. Note that an acidic component is defined as one that requires that protons be absorbed in order to bring it to the equilibrium pH whereas a basic one is one that requires that protons be supplied in order to bring it the equilibrium pH.

Some of the Martin's problem understanding buffering may be because, though chemistry and math are the same, the numbers that go into the equations when considering the buffering that takes place in a mash are not the same as when looking at the buffers we buy for calibrating a pH meter or any similar situation where we are trying to hold pH constant against chemical stress. Buffering is simply the ability of a system to resist pH change when acid or base is added to it. It is expressed, therefore, in terms of the ratio of a incremental acid or base addition to the incremental shift in pH it causes in units of mEq/pH. If it takes a lot of acid to bring about a small pH change the system is a good buffer.

Buffering depends on pH. It is measured by adding acid to the system and recording pH. A plot of total acid added vs. pH forms the titration curve for the system below its intrinsic pH. Base increments are then added to an identical system and the plot of total base added vs pH is the other half of the titration curve. As the curve shows mEq (acid +; base -) vs pH its slope at any particular pH is the buffering (mEq/pH) at that pH.

The titration curve for phosphoric acid looks sort of like a staircase (it is in the Palmer book), that is, it has flattish (tread) portions where the slope is very shallow and vertical (riser) portions where the slope is steep. A solution of phosphates with pH near a riser (one of phosphoric acid's pK's e.g. 7.2) will have high buffering capacity and indeed the 7.00 buffer we use for calibration is made from phosphoric acid. Conversely, at mash pH, where the curve is flat, the buffering of a phosphate system is poor explaining why the '5.2' product does not work. Phosphate buffers better at some pH's than others.

The titration curves of malts are not staircase like. They are much smoother (there are some examples in the Palmer book) and while their slopes are not constant (if they were mash pH prediction would be a lot easier) they do have more buffering capacity at one pH as opposed to another it is not appreciably better than at any other. When malts are blended, as in a mash, the combined curve is even smoother and the preferential buffering even less.

I no longer worry if I measure an initial pH that is not at the pH I've targeted with my water adjustments. I continue to monitor the pH and have consistently seen the pH move as pointed out above.

If you consistently see migration to 5.4 that only means that you consistently brew beers with equilibrium pH's close to 5.4, a not unreasonable thing to do. What happens if you brew a beer with mash equilibrium pH 5.3. Or 5.5?

 

[ajdelange]

Since it is a rainy day I took the malt parameters for Weyermann's regular Pils malt and Briess' 20 L caramel and used them to calculate the titration curve for a DI water mash made up of 80% of the base malt with the rest the caramel. I then differentiated this curve. At pH's of, respectively, 5.3, 5.4 and 5.5 the buffering capacities are, respectively 54.6, 50.5 and 47 mEq/pH•kg. The buffering capacity falls monotonically between 4.5 and 5.8 (and beyond but we go beyond with trepidation because the individual malt properties are represented as polynomial fits). There is, thus, no buffering in the sense of a preferred pH, i.e. a pH at which buffering capacity peaks relative to pH values in the neighborhood of the peak. It is thus that we speak of the properties of 'a buffer'. But the mash does resist change in pH upon acid or base stress - just not preferentially at any particular pH. It holds pH better at 5.3 than it does at 5.4 but not as well at 5.5 relative to 5.4.

 

[mabrungard]

If you consistently see migration to 5.4 that only means that you consistently brew beers with equilibrium pH's close to 5.4, a not unreasonable thing to do. What happens if you brew a beer with mash equilibrium pH 5.3. Or 5.5?

It's pretty clear that AJ doesn't understand my original message. I'm not typically targeting pH's of 5.4. For the cases I mentioned, I am targeting pH's like 5.3 or 5.5 and the long-duration pH tendency is to move toward 5.4.

This innate mash buffering tendency toward 5.4 is something that I've seen for years and even someone more 'reputable' than me (Weyermann), has shown to be true in a Powerpoint presentation that they produced on mashing pH.

 

[Silver_Is_Money]

What I find interesting in the Weyermann presentation is their claim that the lactic acid content of their acidulated malt lies at somewhere between the extremes of 1% and 2%, whereas independent observations that I've seen tend to place it at typically more like 3% to perhaps 3.1% by weight.

They also strongly emphasize that unless acidulated malt exceeds a whopping 10% of the grain bill by weight it will remain undetectable by the senses with regard to our sensory ability to detect souring or acidification.

And at one juncture they state that ideal mash pH's range from 3.2 to 4.8, when they must really mean finished beer pH's (for flat beer).

The entire presentation seems replete with nagging flaws.

 

[ajdelange]

It's pretty clear that AJ doesn't understand my original message. I'm not typically targeting pH's of 5.4. For the cases I mentioned, I am targeting pH's like 5.3 or 5.5 and the long-duration pH tendency is to move toward 5.4.

No, I guess I don't. It seems that you are saying that it doesn't matter what you target, you will wind up at 5.4 eventually regardless of your choices of malts, acid additions etc. Is that what you mean to say? How long does this take?

This innate mash buffering tendency toward 5.4 is something that I've seen for years

I've never observed this in lab or brewery but in the lab I don't measure beyond about half an hour (because pH is stable at that point) nor beyond the duration of the mash in the brewery.

and even someone more 'reputable' than me (Weyermann), has shown to be true in a Powerpoint presentation that they produced on mashing pH.

I'd like to see that presentation. Got a URL? All I can find on their website is a presentation on mash pH which does not mention this 'buffering' but does contain the glaringly incorrect statement:

Mash acidification enhances phosphate
buffering (= resistance to change in pH-value
upon dilution of solution)

 

[ajdelange]

What I find interesting in the Weyermann presentation...

Is this "pH in the Brewery, A Much Understimated Brewing Variable"? Is this the one Martin is referring to? It is the one that I pulled the quote from in my last post

is their claim that the lactic acid content of their acidulated malt lies at somewhere between the extremes of 1% and 2%, whereas independent observations that I've seen tend to place it at typically more like 3% to perhaps 3.1% by weight.

If I look at the sauermalz I have measured and ask "How many protons do I get from it in going from its DI mash pH (3.62) to a reasonable target mash pH of 5.5 the answer is 343 mEq/kg. If I add lactic acid to a mash which ends up at pH 5.5 a mol delivers 978 mEq protons. A mol of lactic acid is 0.09 kg so that the acidifying power of lactic acid to pH 5.5 is 978/.09 = 10867 mEq/kg. Thus a kg of this sauermalz is equivalent to 343/10867 = 0.031 kg of lactic acid from which we might conclude that it is, effectively 3.1% lactic acid by weight. There is a bit more to it than that as some of the acid applied is used to transition the pH of the malt. Assuming the malt is, as I believe, a relatively light caramel much of this is returned when the malt comes back to 5.5 which is probably pretty close to the pHDI of the malt before it is acidulated.

The entire presentation seems replete with nagging flaws.

I did find the one if we are talking about the same presentation.

 

[ajdelange]

It just dawned on me that I have done many test mashes in which the pH of the mash was recorded over time and displayed on the computer screen. These were made in order to obtain data for reconstruction of individual malt titration curves from simple polynomial expansions. Each mash was 'designed' for a particular pH (though it wasn't known what that was until the measurement was made) by determining an amount of acid or base to be added to a ground sample of the malt in question. The amounts of acid or base were varied widely enough that the DI mash pH of the malt and reasonable values of mash pH (up to 6 or so) were spanned.

The pH vs time traces behaved as described a few posts back. If acid was used the initial pH was very low, then rose rapidly at first and then continued to increase more slowly eventually approaching the equilibrium pH. If base was used the pH was initially high, plummeted initially and then slowly decreased assymptotically towards the equilibrium pH. In no case was any deviation from this behaviour noted i.e no reversion to pH 5.4 or any other pH (unless 5.4 was the equilibrium pH). In many cases I'd wander off for a phone call or something and the recordings would go well past the 35 minutes where I usually terminated because the traces were clearly close to their assymptotes by then. No reversion to pH 5.4 (or any other pH) was observed in those cases either. I was not looking for such a reversion because the chemistry has no explanation for such a reversion nor did my experience in the brewery ever suggest that such a thing was happening. But if it had happened it would have stuck out like a sore thumb in the pH vs time plot and I'd have taken note. Of that I am certain.

This evidence should convince Martin that he ought to be considering confirmation bias with respect to his observations. That's the only 'science' I can think of to explain what Martin is seeing.

Now I have seen reactions (neutralization of carbonate) take several hours but I don't think that's what's involved here and mashes don't take several hours (except multiple decoctions) and I've never seen reversion to 5.4 in a triple decoction mash either. But I try to keep an open mind. If there is some evidence for this I welcome the opportunity to look at it.

 

[Silver_Is_Money]

Is this "pH in the Brewery, A Much Understimated Brewing Variable"? Is this the one Martin is referring to? It is the one that I pulled the quote from in my last post

That is the one which I'm referencing. Not sure about Martin.

 

[Silver_Is_Money]

..... Thus a kg of this sauermalz is equivalent to 343/10867 = 0.031 kg of lactic acid from which we might conclude that it is, effectively 3.1% lactic acid by weight.

I believe that work done by Kai Trosester places it generally within the 3.0% to 3.1% lactic acid range as well. On the website which I've linked below he has a chart which indicates that 0.085 mL of 88% Lactic Acid and 3 grams of acidulated malt both deliver 1.0 mEq worth of acid.

http://braukaiser.com/wiki/index.php/Mash_pH_control

I admittedly haven't really delved into this much, but my initial guess based upon a single recipe sampling is that Bru'n Water defaults Acidulated Malt to somewhere closer to 2% Lactic Acid by weight. I quickly added a recipe to Bru'n Water whereby it calculated that 1.8 mL of 88% Lactic Acid was required to hit a mash pH of 5.40. The same recipe hits a mash pH of 5.40 in Bru'n Water with the addition of 3.5 ounces of Acidulated Malt.

For Kai Troester: 35.24 grams of Acidulated Malt = 1 mL of 88% Lactic Acid
For Bru'n Water: 55.13 grams of Acidulated Malt = 1 mL of 88% Lactic Acid

 

[ajdelange]

I believe that work done by Kai Trosester places it generally within the 3.0% to 3.1% lactic acid range as well. On the website which I've linked below he has a chart which indicates that 0.085 mL of 88% Lactic Acid and 3 grams of acidulated malt both deliver 1.0 mEq worth of acid.

To pH 5.5 88% lactic acid is 11.5 N meaning that it would take 1/11.5 = 0.087 mL to deliver 1 mEq - close enough for government work.

The sauermalz (Weyermann;'s) I referenced in the earlier post delivers 343 mEq/kg (to pH 5.5) meaning that it would take 1000/343 = 2.91 grams to deliver a mEq.

A correspondent measured a sample of Weyermanns sauermalz He only took enough points to define the first two coefficients but his measurements show a yield of 419.708 mEq/kg (to pH 5.5) implying that 2.4 grams would yield 1 mEq and that the equivalence is 3.9%.

Kai's original measurements on Weyermanns Sauermalz only allow determination of the average buffering from pHDI to pH 5.7. Even so we can estimate the acidity to other pH values by using this value as the first buffering coefficient (the first buffering coefficient is actually the slope of the titration curve at pHDI). This gives, for Kai's measurement, to a pH of 5.5 a yield of 325.5 mEq/kg meaning that 3.1 grams would suffice to release 1 mEq. This implies an equivalence of 3.0%. I think these numbers (which would change slightly for other mash pH's) are satisfyingly close.

 

[Silver_Is_Money]

So to be a bit more precise, for Kai's tested acidulated malt sample at an adjusted target pH of 5.5:

35.63 grams of Acidulated Malt = 1 mL of 88% Lactic Acid

And for your tested acidulated malt sample at a target pH of 5.5:

33.45 grams of Acidulated Malt = 1 mL of 88% Lactic Acid

Presuming that I have extended both of these properly, the two figures (yours and Kai's) are very close (within about 6%), and when averaged would come in at about 3% lactic acid content by weight.

And lastly, your correspondents acidulated malt sample was noticeably higher in lactic acid than both of the above listed samplings, and was a whopping 3.9% lactic acid by weight.

 

[Silver_Is_Money]

What 'nominal' percentage of lactic acid by weight would Acidulated Malt actually need to contain in order to match Weyermann's long standing advice that 1% of it by weight of the grist bill will lower the mash pH by 0.1 points?

On first assumption, Weyermann likely shoots for this 'nominal' lactic acid concentration, so that for most lots of their acidulated malt, their pH shift advice will be a truism.

 

[ScrewyBrewer]

The grain bill was 5# 2row and 3.5# wheat with 0.75# flaked wheat. I added the acid at 5mins into mash (forgot to do it before dough-in). Then I added flaked at 20 mins and turned on my recirculation. Is there anything I should change on the malt bill tab besides base/crystal/acid/roast?? I usually use BeerSmith for my SRM.

You mentioned a ' new Wards Lab report', did you mix your tap water with RO water, or use straight RO water. Either way it would be helpful to know what your mineral levels were.

 

[ajdelange]

What 'nominal' percentage of lactic acid by weight would Acidulated Malt actually need to contain

I'm really not too sanguine about talking about the lactic acid 'content' of sauermalz as it is a malt and therefore contains acids and or bases other than lactic. I have theorized that sauermalz starts as a caramel malt in which case some of the mEq we have been attributing to the lactic acid on the malt might be coming from the malt itself. In this case the actual lactic acid content would a bit less than 3%. Conversely, if sauermalz is made from a base malt some extra acid would be needed to neutralize the alkalinity of that malt and the 'content', or at least the amount sprayed on, would have to be a bit more than 3%. It is, thus, I believe, better to talk in terms of the equivalent lactic acid content.

We still have a paradox here. When Weyermann says their product contains 2% lactic acid they should know. If they take a kg of malt and spray 20 grams of lactic acid on it, that's 2%. This makes me think that the process is more like moistening malt and spraying lactic culture on it so that the acid that winds up on the malt is produced on the malt by the bacteria rather than being sprayed on to it. Others, who claim to know, assure me that I am wrong about this.

in order to match Weyermann's long standing advice that 1% of it by weight of the grist bill will lower the mash pH by 0.1 points?

That's going to depend on the buffering capacity of the mash. If that is about 45 mEq/kg*pH it is going to take 4.5 mEq to lower the pH of 1 kg of mash by 0.1. At 3 grams sauermalz per mEq that means 13.5 grams total required which is 1.35%

On first assumption, Weyermann likely shoots for this 'nominal' lactic acid concentration, so that for most lots of their acidulated malt, their pH shift advice will be a truism.

They recognize in the presentation that this rule of thumb is just that: a rule of thumb and that results may vary. The interesting thing is that the rough agreement with their ROT is consistent with about 3% effective acid content; not 1-2%.

 

[Silver_Is_Money]

We still have a paradox here. When Weyermann says their product contains 2% lactic acid they should know. If they take a kg of malt and spray 20 grams of lactic acid on it, that's 2%. This makes me think that the process is more like moistening malt and spraying lactic culture on it so that the acid that winds up on the malt is produced on the malt by the bacteria rather than being sprayed on to it. Others, who claim to know, assure me that I am wrong about this.

Your thought would seem to fall within the proper guidelines of the Reinheitsgebot, whereas adding lactic acid straight up might not.

 

[ajdelange]

That aspect of it has occurred to me.

 

[Silver_Is_Money]

That aspect of it has occurred to me.

The Weyermann article which we have been referencing does also state that:

Biologically (naturally) produced lactic acid results in better flavor stability in the finished beer than does artificially produced lactic acid.

More evidence that your thought is the correct one?

 

[ajdelange]

I would assume that the acid source, if sprayed, would be sauergut but as this is pretty weak stuff in terms of its actual acid content you would need to spray (and dry off) a lot of it. I don't know how sauergut could be concentrated (RO, vacuum distillation) without violating Biersteuergesetz.