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Home Brew Forums > Home Brewing Beer > Brew Science > Bicarbonate and Flavor
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Old 05-14-2013, 04:47 AM   #1
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Default Bicarbonate and Flavor

Hey All,

I am making a recipe right now for an Imperial Brown Porter. I have finished with the recipe and am working on the water adjustments in Bru n Water. I am going for the black malty profile but because of my grain bill I am having to really bump up the bicarbonate levels to get a pH that's about 5.2/5.3.

My level of bicarbonate (which I intend to get from pickling lime by adding about 3 grams) is at about 240ppm (Alkalinity 198 and RA 133) which gives me a pH of about 5.3 according to the spreadsheet. Recommended for the profile is 155 ppm.

I have been poking around and can't seem to find anything about off flavors and bicarbonate levels so I am wondering if there might be some from going this high on the bicarbonate? I just have found that one should not go over 250ppm.

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Old 05-14-2013, 04:59 AM   #2
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What is your pH without all that bicarb? Are you starting with RO water? Are you concerned with Alkalinity or bicarb specifically because Pickling Lime is not bicarbonate, it's CaOH which will certainly increase your alkalinity.

I can't imagine having to add that much alkalinity to get your pH to 5.2/3, you would have to be starting out in the mid 4.0's,

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Old 05-14-2013, 05:23 AM   #3
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pH without is 4.9. I could use chalk but it doesn't diffuse as well which is why the lime. I am not using RO water but my water is very soft where I am so only about 27ppm in my base profile

I am mainly concerned that if I have that much alkalinity and bicarbonate that it will produce some sort of off flavor.

In Bru n water pickling lime increases the bicarbonate level which is why I am referring to it that way

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Old 05-14-2013, 02:57 PM   #4
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Pickling lime doesn't add bicarbonate but it does add alkalinity. I can see why one might thing it does though. If you add 1 mmol/L lime you will increase alkalinity by 2 mEq/L or 100 ppm and if you use the approximation that 100 ppm alkalinity stems from 61*100/2 bicarbonate you will conclude that bicarbonate has gone up by 122 when in fact the only increase in bicarbonate will come from conversion of carbonic to bicarbonate because of the increased pH.

Neither bicarbonate nor lime should add any flavor from anions but they will, of course, add calcium in the case of lime or sodium if you get bicarbonate from sodium carbonate or bicarbonate. At mash pH most of added bicarbonate will be converted to carbonic and any added hydroxyl from lime to water.

Bicarbonate doesn't taste very good as you can determine by adding some sodium bicarbonate to a glass of water and tasting but keep in mind the conversion to carbonic at mash pH and also that there will be quite a lot of bicarbonate in your beer from conversion of the CO2 you use to carbonate it. In the matrix of beer it doesn't seem to taste that bad - I think because the pin-prick of the spriziness offsets it.

Adding alkakinity to mash or brewing water is tricky. Chalk, as you have noted, dissolves slowly, reacts more slowly and the calcium in it offsets it's alkalinity somewhat. In the lab I have added chalk to mash and seen the pH drop! The same is true with the calcium in lime: a mmol of lime does not give 2 mEq of alkalinity but perhaps 70% of that. A mmol of sodium bicarbonate does give a meq of alkalinity but it also gives a meq of sodium.

I'd be a bit cautious about adding a lot of alkali to your mash without testing first e.g. making a mini mash and measuring its pH with a decent meter.

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Old 05-14-2013, 06:37 PM   #5
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I guess I should just stick to the bru n water profile as closely as possible. I actually don't have a pH meter right now so I am just assuming that bru n water is correct. Guess that might be a bad idea? Putting as much alkalinity in as I have actually didn't impact the calcium too much. I am at about 90ppm on that.

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Old 05-14-2013, 07:15 PM   #6
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There are two parts to predicting mash pH:
1. The model - how you think malt behaves when subjected to acid or alkali
2. The data you put into the model: the numbers you must put into the model to accurately describe the particular malt you are using.

The models in current use aren't spot on because they don't allow for the fact that mash pH drifts over time. If you tell me a spreadsheet predicts a mash pH of 5.2 my question, being the wise guy I am, would be 'When?'. If it's 5.2 at dough in it may be 5.3 10 minutes later and 5.4 20 minutes after that. In addition to that many of them do not recognize that the buffering of malts changes with pH i.e. they are not linear and many of them assume that they are.

Finally, none of them have measured the malts you are using but have rather assumed parameters based on someone elses measurements of a different bag of malt at some other time. Thus there are lots of sources of error. In many cases the models predict mash pH quite accurately (if the time of measurement is chosen just right) and in other cases they don't. By all means use these models to alert you to the fact that alkali is going to be needed but only trust a pH measurement to confirm that you have added the right amount.

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Old 05-15-2013, 01:47 AM   #7
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I assume you must be starting with a very low alkalinity water, like RO? 3 gm of lime seems like a lot, but I don't know the batch size. You mention this is an Imp Brown Porter, so I guess this has a lot of crystal malt and a decent amount of roast malts. Those factors can push the mash pH down when coupled with a low alkalinity water source. I'm hoping that you aren't simultaneously adding an acid to the mash, since that is counterproductive to producing a desirable mash pH in this case. A mash pH of 4.9 to 5.0 is quite possible, as I've done it with some of my brews (I have to use RO water to brew with).

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Old 05-15-2013, 07:00 AM   #8
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My water is very soft, not quite RO water. Here is the ward report:

pH 9.0
Total Dissolved Solids (TDS) Est, ppm 47
Electrical Conductivity, mmho/cm 0.08
Cations / Anions, me/L 0.6 / 0.6
ppm
Sodium, Na 6
Potassium, K < 1
Calcium, Ca 5
Magnesium, Mg 1
Total Hardness, CaCO3 17
Nitrate, NO3-N 0.1 (SAFE)
Sulfate, SO4-S < 1
Chloride, Cl 5
Carbonate, CO3 6
Bicarbonate, HCO3 15
Total Alkalinity, CaCO3 22

I actually generally don't have any problems brewing any kinds of beers. I recently started doing water adjustments to try to improve the quality of my brews. I made a RIS and used the bitter profile from Bru'n water. I just tasted it and it was very astringent. I am thinking that this is either because i was pulling from the bottom of the keg and getting some sediment or because my mash pH was too high and it extracted tannins. I don't think it was due to over sparging as I am pretty good with that.

Thus, the only thing I can relate this to is possible that I added too much alkalinity to the mash and that extracted tannins. I guess I am just trying to not do that again.

I did recently just get a pH meter so I will actually be able to really test it. I think I will just stick with a low bicarbonate level and see how that goes since my normal water.

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Old 05-16-2013, 12:55 AM   #9
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I'm hoping that you are only adding alkalinity to the mashing water and only to the degree absolutely needed to raise the mash pH into the range you want. I'd suggest a range of 5.4 to 5.5 for a darker beer so that the desirable roast character is extracted from the roast grain. If you are using that tap water with its natural low alkalinity, then there is little chance of drawing tannins out during sparging unless the temperature is too high and the gravity of the final runnings is too low.

With that fine tap water, don't be too surprised if the mash pH does drop lower than you want with a RIS grist. If you have a calibrated meter, I suggest that you add all your mineral additions excepting any alkalinity-increasing minerals and mash as usual. Check the mash pH after about 5 minutes and see if it is low. Then you can decide how much of that alkalinity dose you want to add. I used to be skeptical in the dose that the program calculated, but it has proven correct so far. One thing that AJ pointed out while we were working with Palmer on the Water book, was that lime is not always 'pure'. Sometimes there are impurities or the calcium hydroxide may have reacted back to its chalk form. In any case, Bru'n Water assumes that your lime is pure. That means that you are less likely to overdose the mash...but I strongly recommend that a brewer should ALWAYS err on the side of adding too LITTLE alkalinity than adding TOO MUCH alkalinity. The flavor penalty for low pH is much less severe than with high pH.

Enjoy!

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Old 05-16-2013, 01:08 AM   #10
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Thanks Martin that makes total sense. I actually recently just got a pH meter and will be using it on my next brew which will be a dark beer. It makes sense to add the alkalinity after the mash has started. I am curious if I should even be using lime or if I should use chalk because it's less impactful on the alkalinity? Also, when taking a pH reading I am assuming I want to keep as much grain out of there as possible, no? Thanks for the help.

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