Bicarbonate & Lactic Acid

[dmcmillen]

I've just starting treating my water and am beginning to get a handle on the water chemistry. I'm working on a Munich Helles in Martin's Bru'n Water. My water has 119ppm bicarbonate which is high for a Helles so I'm getting it down to around 30 by diluting the water and then adding Gypsum, CaCl, and Epsom Salt to get all the minerals where I need them. I'm also diluting to bring my sodium down which is at 28.

However, the Mass Acidification is estimating 5.5pH which I think is a little high. When I go back to the water adjustment and add enough lactic acid to bring the pH down, it essentially eliminates the bicarbonate (goes to negative in the spreadsheet). Now that makes sense since carbonate/bicarbonate is a strong alkaline buffer and the acid would neutralize it.

My question is: Do I need any bicarbonate? I know it is not pleasant tasting and in "excessive" amounts is associated with bad tastes. I was trying to keep the level in the 0-50 range which is recommended for pale, light-colored beers. Do we want any bicarbonate/carbonate to make it to the final wort?

I am thinking about not diluting the water as much and using the lactic acid to bring the bicarbonate down, but the little I've played with it, it doesn't take much acid to lower the bicarbonate which comes down a lot faster than the pH.

My head's got too much info so I'm "headed" for a beer to clear it. Thanks for the help!

 

[mabrungard]

In the mash, you do need to essentially neutralize all the bicarb when brewing pale styles. The 119 ppm level isn't crazy high and its similar to the Munich tap water. They neutralize with sauergut (acidified wort) to create their pale beers. Lactate in their beers is a signature flavor nuance, but you won't pick up a twang since the lactate level isn't that high.

 

[dmcmillen]

In the mash, you do need to essentially neutralize all the bicarb when brewing pale styles. The 119 ppm level isn't crazy high and its similar to the Munich tap water. They neutralize with sauergut (acidified wort) to create their pale beers. Lactate in their beers is a signature flavor nuance, but you won't pick up a twang since the lactate level isn't that high.

Thanks Martin. Going to show my ignorance here. Then the acidification that comes from the sauergut is a lactate acidification? Does all acidification create lactate (lactic acid, phosphoric acid...) Chemistry was too long ago.

 

[mabrungard]

Lactic acid is one hydrogen proton plus one lactate ion. Saurergut is a dilute form of lactic acid.

 

[dmcmillen]

Lactic acid is one hydrogen proton plus one lactate ion. Saurergut is a dilute form of lactic acid.

What level does the lactate need to be to be perceivable?

Also, I have .69 gal under my false bottom which is recoverable, so as an example, if my mash requires 4 gal I figure my total mash water to be treated as 4.69 but 4 gal for mass acidification. Is that correct?

 

[mabrungard]

What level does the lactate need to be to be perceivable?

The most typically reported taste threshold for lactic acid is 400 ppm. It takes a little less than 1.5 mL of 88% lactic per gallon of water to reach that level. However, some tasters report being able to taste it at lower concentrations. Staying below 1 mL/gal is a good idea.

 

[trentm]

The most typically reported taste threshold for lactic acid is 400 ppm. It takes a little less than 1.5 mL of 88% lactic per gallon of water to reach that level. However, some tasters report being able to taste it at lower concentrations. Staying below 1 mL/gal is a good idea.

Thanks for this info Martin! To stay under this threshold would you consider the entire volume of brewing liquor or final beer volume or just mash water volume?

 

[ajdelange]

I've just starting treating my water and am beginning to get a handle on the water chemistry. I'm working on a Munich Helles in Martin's Bru'n Water. My water has 119ppm bicarbonate which is high for a Helles so I'm getting it down to around 30 by diluting the water and then adding Gypsum, CaCl, and Epsom Salt to get all the minerals where I need them. I'm also diluting to bring my sodium down which is at 28.

So assuming your blend is at pH 7 you have alkalinity of 26 (~0.5 mEq/L).

However, the Mass Acidification is estimating 5.5pH which I think is a little high. When I go back to the water adjustment and add enough lactic acid to bring the pH down, it essentially eliminates the bicarbonate (goes to negative in the spreadsheet).

How can you have negative bicarbonate? If you add enough acid to reduce the pH of the mash to 5.4 (to pick a number) the remaining bicarbonate from the water will be 3.6 mg/L, not a negative number. Even as low as pH 5 there are still 1.53 mg/L remaining. It never goes to 0 (pH 0 : .00002 mg/L). Bru'n water uses bicarbonate as some sort of proxy for alkalinity but even alkalinity stays positive until pH reaches 4.5. So I don't really know what it means but it doesn't mean bicarbonate in a lot of cases.

Now that makes sense since carbonate/bicarbonate is a strong alkaline buffer and the acid would neutralize it.

Bicarbonate is a weak base and weak acid (pKa = 6.38) at pH > pKa and a weak base at pH < pKa. That is why there is still finite bicarbonate at mash and even beer pH.

My question is: Do I need any bicarbonate?

No, unless you need it to neutralize some acid from say a dark malt in order to reach mash pH.

I know it is not pleasant tasting and in "excessive" amounts is associated with bad tastes.

At mash pH (5.5) all but 12% of the bicarbonate has been converted to carbon dioxide and driven off by the heat of the mash. At beer pH (5.4) that percentage has been reduced to 1.3%. If you were to put 20 mmol (1.68 grams) of bicarbonate in each liter of your water for some bizarre reason you would never reach mash pH unless you added 18.75 mEq acid in which case you would have, in the mash, 134 mg/L bicarbonate remaining and that, with the 19.75 mmol acid anion would make for some pretty weird beer I'd think. If you are going to use bicarbonate to keep pH up make a note of how much is going to be required and the residual that might exist at mash and beer pH. The numbers should be small - much less than the bicarbonate created when beer is carbonated to a couple of volumes.

I was trying to keep the level in the 0-50 range which is recommended for pale, light-colored beers. Do we want any bicarbonate/carbonate to make it to the final wort?

In pale beers we want acid - not alkali. I don't know who is recommending 50 mg/L for pale beers but I'd like to talk to him.

I am thinking about not diluting the water as much and using the lactic acid to bring the bicarbonate down, but the little I've played with it, it doesn't take much acid to lower the bicarbonate which comes down a lot faster than the pH.

When it comes to pH control you are really concerned about alkalinity and not so much the implied bicarbonate level. Alkalinity is a measure of the amount of acid required to move a water sample to pH 4.5. It is the number of mEq of acid required to get 1 L of sample to pH 4.5. The brewer doesn't need to get to pH 4.5 but only to mash pH of around 5.5. He will need about 90% of the acid it takes to hit 4.5 to get to 5.5. Thus if he has water of alkalinity 2 mEq/L (if alkalinity is expressed 'as CaCO3' then divide by 50 e.g. 100 ppm as CaCO3 = 2 mEq/L) and plans to mash with 10 L of it he is going to need 0.90*10*2 = 18 mEq of acid. Eighty-eight percent lactic acid is 11.5 N (each cc contains 11.5 mEq). Divide the number mEq needed by the normality to get the number of cc needed (e.g. 18/11.5).

My head's got too much info so I'm "headed" for a beer to clear it.

Should work.

 

[dmcmillen]

Thanks AJ. I appreciate all comments and help. By the way, the beer did help last night. Just needed a little attitude adjustment. I'm afraid I'm a bit at the dangerous level right now but with everyone's help I think I'm getting a better understanding of the water chemistry. Been too damn long since I took chemistry.

So assuming your blend is at pH 7 you have alkalinity of 26 (~0.5 mEq/L).

I'm taking these numbers directly off the Bru'n Water spreadsheet. The starting alkalinity of my source water is 99, the final blend is 4.

How can you have negative bicarbonate? If you add enough acid to reduce the pH of the mash to 5.4 (to pick a number) the remaining bicarbonate from the water will be 3.6 mg/L, not a negative number. Even as low as pH 5 there are still 1.53 mg/L remaining. It never goes to 0 (pH 0 : .00002 mg/L). Bru'n water uses bicarbonate as some sort of proxy for alkalinity but even alkalinity stays positive until pH reaches 4.5. So I don't really know what it means but it doesn't mean bicarbonate in a lot of cases.

First of all, I should have had that beer sooner because I was reading the spreadsheet incorrectly. Adding lactic acid to bring my pH from 5.5 to 5.4 brought the bicarbonate from 59.9 (50% diluted) to 4.3. However, continuing to add more lactic acid does indeed cause the spreadsheet bicarbonate to go negative as the pH drops. If I wanted to take it to 5.3 for example, the "reported" bicarbonate would be negative.

Bicarbonate is a weak base and weak acid (pKa = 6.38) at pH > pKa and a weak base at pH < pKa. That is why there is still finite bicarbonate at mash and even beer pH.

Good explanation. That helps a lot. Most of the information I have been reading describe carbonate/bicarbonate as a "Strong Alkaline Buffer"

No, unless you need it to neutralize some acid from say a dark malt in order to reach mash pH.

That is my understanding of the use of bicarbonate. That's why I asked the question if I needed any for the Helles.

In pale beers we want acid - not alkali. I don't know who is recommending 50 mg/L for pale beers but I'd like to talk to him.

Palmer (among others) in "How to Brew":

Bicarbonate (HCO3-1)
Molecular Weight = 61.0
Equivalent Weight = 61.0
Brewing Range = 0-50 ppm for pale, base-malt only beers.
50-150 ppm for amber colored, toasted malt beers, 150-250 ppm for dark, roasted malt beers.

My understanding of this was that we don't want too much for pale, base-malt only beers or we probably won't get to desired pH. I just didn't know whether I needed any. Now from you and Martin I believe I understand it's purpose better.

When it comes to pH control you are really concerned about alkalinity and not so much the implied bicarbonate level. Alkalinity is a measure of the amount of acid required to move a water sample to pH 4.5. It is the number of mEq of acid required to get 1 L of sample to pH 4.5. The brewer doesn't need to get to pH 4.5 but only to mash pH of around 5.5. He will need about 90% of the acid it takes to hit 4.5 to get to 5.5. Thus if he has water of alkalinity 2 mEq/L (if alkalinity is expressed 'as CaCO3' then divide by 50 e.g. 100 ppm as CaCO3 = 2 mEq/L) and plans to mash with 10 L of it he is going to need 0.90*10*2 = 18 mEq of acid. Eighty-eight percent lactic acid is 11.5 N (each cc contains 11.5 mEq). Divide the number mEq needed by the normality to get the number of cc needed (e.g. 18/11.5).

Very useful. Thanks.

 

[ajdelange]

By the way, the beer did help last night.

Good! Just about to go get one.

If I wanted to take it to 5.3 for example, the "reported" bicarbonate would be negative.

I really wish Martin would fix this but he won't.

Palmer (among others) in "How to Brew"

John has come a long way since he wrote that. He is working on the second edition and we expect recommendations will be a bit more up to date.