Water adjustment and flavor expectations

[winvarin]

I continue in my experimentation with water and mash pH adjustment. Looking for a little insight. I brewed a standard bitter last weekend. I tasted the beer last night trying to catch that proper English aroma/flavor profile at just the right moment so that I can crash cool and lock it in (sorry, a bit unrelated to my reason for posting).

At any rate, last night's tasting had a lot of good flavor/aroma, and one out of place aroma that I am trying to put my fingers on. The flavor can only be described as "tart".

Here are the particulars on the beer and my water adjustments:

Recipe -
8.5# Golden Promise
.75# Victory
.75# of 10L Crystal
.5# of Amber Malt
.25# of Acid malt

32 IBU
.56 ounce Target (60 min)
.28 ounce Challenger (15 min)
.42 ounce Northdown (15 min)

WLP002

Water profile
Ca 56
Mg 26
Na 23
Cl 10
So4 9 (adjusted because it is SO4-s)
HCO3 302

My adjustments (primarily to combat the high alkaline water)
- The 4 ounces of Acid malt
- 3:1 dilution (75%) of my water with distilled water
- Mash water additions (4 g CaSO4 and 2 g CaCl in 3.25 gallons)
- Sparge Water additions (7 g CaSO4 and 3g CaCl in 6 gallons - I mainly went with what -TH-s spreadsheet recommended based on the Mash water)

My results
- Mash pH 5.1 (with the margin of error on my meter, that means I was likely 5.05-5.15)
- Per -TH-'s sheet, I should have hit an RA of -40
- As noted above, the very slight "tart" flavor (aroma and the other flavor components were spot on for what I am expecting of an English session bitter)

I have 3 possible explanations I can come up with for the tartness. I am throwing this out to the Brew Science collection of experts to see if you can help by supporting, or discounting any of them:

1. The beer is just "green". I started tasting this early because I want to try to capture the beer at a point in time, cold crash and bottle with fresh yeast. It's possible that the beer is just not ready yet.

For more on why am doing this, check out https://www.homebrewtalk.com/f163/british-yeasts-fermentation-temps-profiles-cybi-other-thoughts-221817/index26.html#post2728714

2. Some yeast derived flavor. The sample I pulled had a small amount of sediment/slurry in it. Is it possible that this tart "bite" came from tasting the yeast as I sampled the beer?

3. My water adjustment and acid malt usage. Did I overdo it? The 5.1 mash pH doesn't seem to indicate I did. And the amount of acid malt was right around 2% of my total grist. But every time I use acid malt, i am always worried that I am going to impart a "tang" to the beer. And I am not entirely certain what an RA of -40 will do to the flavor of my final product.

Any input?

 

[mabrungard]

A mash pH of 5.1 certainly does suggest that you over acidified. I find that a mash pH of less than about 5.3 (room temp measurement) has the potential to present tartness.

This water is very hard and very alkaline. Its mostly temporary hardness and I find that its susceptible to decarbonating during heating. You can read more about Decarbonation by Boiling here:

http://www.homebrewersassociation.org/forum/index.php?topic=5792.0

That article presents the premise that during minor heating to mashing temps, that CO2 dissolved in the water will be forced from the water which removes some dissolved CaCO3 from solution also. As we know, undissolved chalk, does not contribute all of its predicted alkalinity. That reduces the alkalinity of the water and the mash pH can be depressed more than might be expected per a brewing water program. Even my program, Bru'n Water does not take this into account. Its a tough situation.

I see that you dilute to address the alkalinity and hardened with gyp and CaCl which really depressed the residual alkalinity. All these factors along with the large amount of acid malt (that probably was not needed in the first place) really pushed your pH down.

Too many adjustments in this case. I strongly recommend that you download Bru'n Water to learn where you went wrong. A large section on brewing water knowledge is included in that program. The link to the download is in the link in my signature line.

Enjoy.

 

[samc]

1. The beer is just "green".

It's possible that the beer is just not ready yet.

Yeah, that is the truth. How can you dissect the process at this point until you know what it really tastes like?

I do minimal water adjustments, basically because I don't really understand enough of the chemistry. But I do know what I like my beer to taste like and I am in that sweet spot of doing the right thing with out thinking about it.

 

[ajdelange]

The first question would be "What is the pH of the beer?".

The second would be "What was the pH of the mash 15 min - 1/2 hr after dough in?"

And the third "Were the pH measurements made at room temp?"

What you did should not have lead to inordinately low pH. I don't know your malt but supposing it to have a DI water mash pH of about 5.65 and given the alkalinity and dilution of your water you had an RA of -35 which would give you an expected pH shift in a base malt only mash of about 5.59. 2% acid malt would drop that to about 5.39. An observed 5.1 would require a drop of 0.29 for the other malts. That seems a lot but I suppose it is possible. The reason for the second question is that when sauermalz is used the pH of the mash is always low at a reading made immediately after dough-in but it rises over the first half hour or so to settle appreciably higher. It is, therefore, important to check pH a couple of times after dough in. In fact, it is so easy to take a measurement once you have calibrated the meter that you should do it at dough in, after the completion of each decoction or step, when going into the kettle and at the end of the boil.

In cases where you have a pH meter available you should rely on it rather than spreadsheets, rules of thumb, phases of the moon or my advice. Make a test mash and check the pH. Be guided in you additions of acid or alkali by what the test mash shows. You should only have to do this a few times. Thereafter you should know what to expect from the materials you use. When doing something new hold out the acid, sauermalz or alkali and check mash pH. If it is just where you want it don't add anything. If too low, add alkali, if too high, acid. And so in this case given that you added so much calcium it might have been wise to use half the sauermalz and then added the rest if needed. But I'm still a little suspicious of a mash pH that low given my guesses about your malts. I assume the meter was recently calibrated?

Then your comment about the accuracy of the meter. I assume it has a resolution of 0.1? In this case a reading of 5.1 could mean a pH of from 5.0 to 5.2 depending on how the meter quantizes.

Finally, beer is acidic stuff, especially ales which can have pH's as low as 4.3 whereas lagers usually run higher. That's why I suggest checking the beer's pH. The acid responsible for this tartness is secreted by the yeast. They will secrete more or less as required to establish the pH they are happy with (or, more to the point, that their potential competitors are unhappy with). Thus a slightly low mash pH is unlikely to have much of an effect on the pH of the beer unless you overwhelmed the yeast with sauermalz but at the 2% level this shouldn't be the case.

Now green beer does have its unpleasant flavors. I don't generally think of them as being tart, however. And yeast does have a bite but while it is sharp I wouldn't call it tart. So I'd definitely taste comparatively over the next couple of weeks. I expect you are going to be fine but if tartness remains try again w/o the sauermalz.

 

[ajdelange]

That article presents the premise that during minor heating to mashing temps, that CO2 dissolved in the water will be forced from the water which removes some dissolved CaCO3 from solution also.

I tend to doubt it. The carbo moieties in water at pH 7 are distributed as 19% carbonic, 81% bicarbonate and 0.03% carbonate. When water hits mash and pH drops to 5.2 (assuming the brewer has done the things he needs to do to insure this) they are redistributed 94% carbonic, 6% bicarbonate and 0.00004% carbonate i.e a drop of 1.8 pH reduces carbonate ion concentration by 3 orders of magnitude. Or perhaps it is better to look at it from the saturation pH perspective. A water at pH 7 at 20 °C with alkalinity 165 and calcium hardness 140 has a CaCO3 saturation pH of 7.43 and is thus undersaturated with respect to that salt (though it is over saturated WRT CO2 - equilibrium PaCO2 = 0.019 atm). Adding enough acid to reduce pH to 5.2 raises saturation pH to 8.52 which is 3.3 pH units higher than the water pH as opposed to only 0.43 at pH 7. The equilibrium partial of CO2 is now 0.96 atm. Now raising the temperature to 65°C decreases the solubility of CaCO3 so that the saturation pH is now reduced to 7.85 but this is still 2.65 higher than the pH so precipitation of CaCO3 is not likely. OTOH the Henry coefficient has also decreased (CO2 is less soluble) so that the water is even more oversaturated WRT to CO2 (equilibriun PaCO2 = 0.19 atm). CO2 will leave the solution but CaCO3 will not.

At least that's what the thermo tells us. But experience tells us the same thing. If we want to make decarbonation by heating (boiling is not necessary if another means of sparging out the CO2 is provided) effective we raise the pH to get it higher (or if already higher, higher still) than the saturation pH. If we reduce pH we are moving in the wrong direction WRT saturation pH.

[Edit] Afterthought: In mash part of the acid comes from the reaction of inorganic phosphate released from the malt coalescing with calcium in the liquor to form apatite which precipitates out. This removes calcium from the wort thus raising the saturation pH still further (making precipitation of calcium carbonate even less likely).

 

[winvarin]

The first question would be "What is the pH of the beer?".

That I do not know. I was planning to take another taste sample this morning. I will take a pH reading as well and report back

The second would be "What was the pH of the mash 15 min - 1/2 hr after dough in?"

I took a single pH reading during the mash. I pulled an all liquid sample via the valve at the bottom of my MLT about 10-15 min after dough in

And the third "Were the pH measurements made at room temp?"

Room temperature more or less. I pulled the sample from my mash and let it sit for about 15 min. My thermapen registered 79F on the sample. My pH meter which claims to be ATC, registered the sample as 80F

I assume the meter was recently calibrated?

I bought the larger bottles of 4.01, 7.01 and storage solution recommended by my meter's manufacturer. I calibrate at the beginning of each brew day and store in the storage solution between brew days.

Then your comment about the accuracy of the meter. I assume it has a resolution of 0.1? In this case a reading of 5.1 could mean a pH of from 5.0 to 5.2 depending on how the meter quantizes.

The meter has a resolution of 0.1, yes. But it is advertised to have a margin of error of +-0.05. I thought that would mean that I was looking at a range of 5.05-5.15. Is that not correct?

Now green beer does have its unpleasant flavors. I don't generally think of them as being tart, however. And yeast does have a bite but while it is sharp I wouldn't call it tart. So I'd definitely taste comparatively over the next couple of weeks. I expect you are going to be fine but if tartness remains try again w/o the sauermalz.

"Tart" is a subjective term. I actually like tart, acidic things. I have a taste for them and identify them easily in food and drinks I taste. Not that I was looking for this beer to exibit that character though. I tasted the flavor as tart, but only lightly so and only on the sample's finish. I could still distinctly pick out the hops and malt. And there was nothing about the aroma that I would call tart.

My wife does not like hoppy beers at all so she tried the sample grudgingly. She picked up on the flavor that I was describing. But she did not call it tart at all. Her words were "Harsh. Not harsh like some of the hoppy beers you make so I don't think it's from hops. It just tastes a little harsh to me."

I'm sure that could mean almost anything.

One additional question AJ. I know you often preach getting RA down. And that advice has served me well in recent batches. But is there a guideline for where RA should land? Is there a general guideline or at least targets by style?

 

[mabrungard]

There is not a definition for where RA should be for a style, but there could probably be a range that it should fall in for a style. There are too many variables from the grist. Bru'n Water helps to decipher that.

 

[winvarin]

Update -
I just pulled a sample for taste and pH. The tartness I picked up 2 nights ago is significantly diminished. I am leaning toward it being yeast derived as the wlp002 continues to floccuate nicely. The beer has dropped largely clear.

The aroma has the strong malt/grain nose I was hoping to get. The grain and hops are fairly evident in the flavor as well. The beer is still a tad tart, but nowhere near where it was on Thursday night.

pH measured 4.2 (at 69.5F).

 

[ajdelange]

That I do not know. I was planning to take another taste sample this morning. I will take a pH reading as well and report back

I'll respond here to your reported measurement of pH 4.2 here. Recognizing that an 0.1 resolution meter could imply pH between 4.1 and 4.3 I'll just comment that HBS&Y says the range of pH for finished British beers is 3.9 - 4.2. That's actually lower than I remembered but clearly you are in or slightly above that range. To paraphrase Duke Ellington "If it tastes tart it is tart" but if it tastes tart and a glass of your favorite UK product doesn't then the tartness you are tasting is not likely to be caused by the pH.

I took a single pH reading during the mash. I pulled an all liquid sample via the valve at the bottom of my MLT about 10-15 min after dough in

Thought that might be the case. Try a second reading later on next time. It will probably fall right about where you want it to.

Room temperature more or less. I pulled the sample from my mash and let it sit for about 15 min. My thermapen registered 79F on the sample. My pH meter which claims to be ATC, registered the sample as 80F

That will have pushed the reading down some. With an 0.1 resolution meter that may or may not have caused an effect depending on where the pH was. You measured about 10°F higher than "room" temperature. That would induce a pH shift of about 0.033 pH. Suppose your meter's quantization rule is truncation. If the true pH were 5.232 the meter would read 5.2 at room temperature but lowering the true pH by 0.033 to 5.199 would cause such a meter to read 5.1. OTOH if the true pH were 5.15 lowering by 0.033 would have no effect on the displayed value. It would read 5.1 in both cases.

I bought the larger bottles of 4.01, 7.01 and storage solution recommended by my meter's manufacturer. I calibrate at the beginning of each brew day and store in the storage solution between brew days.

Excellent.

The meter has a resolution of 0.1, yes. But it is advertised to have a margin of error of +-0.05. I thought that would mean that I was looking at a range of 5.05-5.15. Is that not correct?

Accuracy and precision are two separate things. If a rifle shoots 6" groups at 100 yards but the average windage miss is very close to 0 and the average elevation miss is about the same then the rifle is accurate by imprecise. Conversely if it shoots 1" groups but the group is far from the center of the bulls eye it is precise but innacurate. Precision of 0.1 implies that every measurement is uncertain by 0.0288 pH (if you really want to know why, ask in another post). But each pH measurement on a sample depends on the reading you got on the sample and the readings you got when you calibrated the meter (i.e. 2 additional readings) and and three temperature readings also subject to error. The ultimate accuracy depends not only on the precision of all 6 of these measurements but on the uncertainty of the pH of the buffers used (how close are their actual pH's to what's on the label) and even the pH of the sample (best accuracy when it's pH is half way between the calibration buffer pHs). So you can definitely have errors greater than ± 0.05 in a meter with 0.1 pH precision.

"Tart" is a subjective term. I actually like tart, acidic things. I have a taste for them and identify them easily in food and drinks I taste. Not that I was looking for this beer to exibit that character though. I tasted the flavor as tart, but only lightly so and only on the sample's finish. I could still distinctly pick out the hops and malt. And there was nothing about the aroma that I would call tart.

My wife does not like hoppy beers at all so she tried the sample grudgingly. She picked up on the flavor that I was describing. But she did not call it tart at all. Her words were "Harsh. Not harsh like some of the hoppy beers you make so I don't think it's from hops. It just tastes a little harsh to me."

If this flavor is harshness from yeast bite, phenolics or anything like that it will pass with time. If it is from low beer pH it won't. See what happens as it ages (lagers).

One additional question AJ. I know you often preach getting RA down. And that advice has served me well in recent batches. But is there a guideline for where RA should land? Is there a general guideline or at least targets by style?

While it is my personal belief that the first rule of brewing water treatment: "Alkalinity = bad" is valid and that the softest water makes the best tasting beer I know there are exceptions and don't push that POV on others who have different approaches. So to my thinking the best RA level is as negative as 50 mg/L Ca++ gives in water with 0 alkalinity (i.e. RA = -31). People brewing after the Primer are going to wind up with RA's in that area. People trying to tailor water to a particular style may (or should) shoot for an RA close to that of the city in which the beer was originally brewed. All the caveats about the quality of popular profiles/recommendations, needing to know what the brewers did with the water they brewed with and the difficulties in synthesizing most profiles (it would be a snap if your LHBS sold calcium bicarbonate powder) go along with this approach. If that's what you want to do the chart at http://www.pbase.com/agamid/image/57446374 may be of help.

What I really tried to campaign against were the spreadsheets which advised adding teaspoons of chalk to 5 gallons of water based on calculations that stouts "needed" +300 ppm as CaCO3 RA based on their SRM values. The latest round of spreadsheets still suggest that chalk should be added if color is high but have toned the recommendations way down.

 

[winvarin]

That will have pushed the reading down some. With an 0.1 resolution meter that may or may not have caused an effect depending on where the pH was. You measured about 10°F higher than "room" temperature. That would induce a pH shift of about 0.033 pH. Suppose your meter's quantization rule is truncation. If the true pH were 5.232 the meter would read 5.2 at room temperature but lowering the true pH by 0.033 to 5.199 would cause such a meter to read 5.1. OTOH if the true pH were 5.15 lowering by 0.033 would have no effect on the displayed value. It would read 5.1 in both cases.

So are you saying that while my recorded pH reading was 5.1, the actual pH of my mash could have been as high as 5.232 and as low as 5.133. But my meter would have still registered 5.1 because of the precision of the meter and the temperature at which I read the sample. The meter is supposed to adjust for temperature. Should I not trust that it did?

If that range is correct, how does the meter's margin of error (+-0.05) factor in?

 

[ajdelange]

This can get pretty hairy pretty fast. The margin of error is probably the standard deviation of errors which are distributed according to a Gaussian law. The standard deviations for the sample error, the two calibration errors, the buffer uncertainty and the temperature errors must all be combined to come up with a single standard deviation number which describes the quality of the measurement. Lets say this is 0.07 just for example. It's going to be bigger than the single measurement uncertainty because of the contributions of the other error sources). 0.07 uncertainty means that there is an approximately 70% chance that the error will be less that 0.07 (plus or minus) and, thus, an approximately 30% chance that it will be greater.

ATC has its benefits and its shortcomings. If you use it it introduces some error which depends on the error in the temperature readings fed into it and on the deviation of the so called isoelectric pH from it's assumed value of 7.00. The deviation from this are usually small because isoelectric pH is usually less than 0.5 and error is insensitive to it. But I found one of my electrodes to have an isoelectric pH of 8.4. I don't use ATC with this electrode.

With all this you may be wondering why you should bother to take pH measurements. It is not usually as bad as I might make it seem. If the meter reads what it should in the buffers then you are probably (bit note the use of the word probably) good to ± 0.07 or so.

 

[winvarin]

As always, I appreciate your willingness to help AJ. I know this may make you cringe, but I think I am OK with the margin of error I have in my current meter. I am learning more about the composition of my mash and how it affects pH in general, so that is a good thing.

The meter reads 4.0 and 7.0 in my 4.01 and 7.01 solutions To me that means I am at least armed with a tool that tells me I am in the ballpark for my mash pH. It is more accurate (and precise) than the test strips I was using. And infinitely better than when I was using neither and just shooting in the dark.

I have picked up enough basic water chemistry and understanding of mash pH, RA and the impact of various minerals to be dangerous. But I've also picked up enough to make my beers better, and at least have a direction to guide my troubleshooting if I make them worse.

That doesn't mean that I won't ask you questions from time to time in order to continue learning. But I am also not going to stress over a few hundredths of a point here and there. I am already making better beer since you and I tackled some of the biggest issues with my brewing water. And so far, I have had success tuning my water for subsequent batches when I try the adjustments on my own and don't get the desired results the first time.

 

[ajdelange]

It is more accurate (and precise) than the test strips I was using. And infinitely better than when I was using neither and just shooting in the dark.

And that's what really counts.