Loss of brewing water Ca++ during mash.

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p_p

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I have ask similar questions before and still struggle to understand, so apologies I ask again. I heard an interview given by a brewer from Lagunitas Brewing Company. He talked about how Lagunitas IPA is brewed and said that they start with 100ppm of Ca, 50% is lost during mash and then they supplement adding CaSO4 in the kettle to reach 75ppm in the final product.

Would someone be able to elaborate on where the 50% comes from?
Are these empirical measurements and therefore one should not assume 50% loss is a fair approximation for all grain bills?

What about Mg++ loss?

Thanks,
p_p
 
Malt contains quite a bit of inorganic phosphate. It reacts with calcium ions to precipitate hydroxyl apatite (the stuff your teeth and bones are made of) releasing hydrogen ions in the process:

10Ca++ + 6H2(PO4)- + 2H2O ---> Ca10(PO4)6(OH)2 + 14H+

If something similar happens with magnesium it would be to a much lesser extent as magnesium salts are much more soluble than calcium.

The reasons most people want calcium in the mash at or above certain levels is to get those hydrogen ions which neutralize the alkalinity of water and base malt, protect the enzymes, insure bright runoff etc. As such, most don't seem to care about the fact that Ca++ has been removed as its role is mainly in the mash. There is, however, one job for it later on is the process and that is to precipitate oxalate as calcium oxalate. If calcium oxalate is not precipitated in the kettle it will precipitate in the finished beer causing gushing and/or in your kidneys causing all kinds of trouble. I have never heard of a brewery being concerned about maintaining a particular level of calcium into the beer.

I would not accept 50% calcium loss as a number applicable to all grists though. I'm sure the actual number depends on a lot of things. It's reasonable to suppose that if the calcium content is originally low (as in water for pilsner) that a higher percentage might precipitate but predicting precipitation is difficult.
 
Malt contains quite a bit of inorganic phosphate. It reacts with calcium ions to precipitate hydroxyl apatite (the stuff your teeth and bones are made of) releasing hydrogen ions in the process:

10Ca++ + 6H2(PO4)- + 2H2O ---> Ca10(PO4)6(OH)2 + 14H+

If something similar happens with magnesium it would be to a much lesser extent as magnesium salts are much more soluble than calcium.

The reasons most people want calcium in the mash at or above certain levels is to get those hydrogen ions which neutralize the alkalinity of water and base malt, protect the enzymes, insure bright runoff etc. As such, most don't seem to care about the fact that Ca++ has been removed as its role is mainly in the mash. There is, however, one job for it later on is the process and that is to precipitate oxalate as calcium oxalate. If calcium oxalate is not precipitated in the kettle it will precipitate in the finished beer causing gushing and/or in your kidneys causing all kinds of trouble. I have never heard of a brewery being concerned about maintaining a particular level of calcium into the beer.

I would not accept 50% calcium loss as a number applicable to all grists though. I'm sure the actual number depends on a lot of things. It's reasonable to suppose that if the calcium content is originally low (as in water for pilsner) that a higher percentage might precipitate but predicting precipitation is difficult.

AJ as always very informative.
Thank you for your time.
pp
 
Malt contains quite a bit of inorganic phosphate. It reacts with calcium ions to precipitate hydroxyl apatite (the stuff your teeth and bones are made of) releasing hydrogen ions in the process:

10Ca++ + 6H2(PO4)- + 2H2O ---> Ca10(PO4)6(OH)2 + 14H+

If something similar happens with magnesium it would be to a much lesser extent as magnesium salts are much more soluble than calcium.

The reasons most people want calcium in the mash at or above certain levels is to get those hydrogen ions which neutralize the alkalinity of water and base malt, protect the enzymes, insure bright runoff etc. As such, most don't seem to care about the fact that Ca++ has been removed as its role is mainly in the mash. There is, however, one job for it later on is the process and that is to precipitate oxalate as calcium oxalate. If calcium oxalate is not precipitated in the kettle it will precipitate in the finished beer causing gushing and/or in your kidneys causing all kinds of trouble. I have never heard of a brewery being concerned about maintaining a particular level of calcium into the beer.

I would not accept 50% calcium loss as a number applicable to all grists though. I'm sure the actual number depends on a lot of things. It's reasonable to suppose that if the calcium content is originally low (as in water for pilsner) that a higher percentage might precipitate but predicting precipitation is difficult.

AJ, a follow up question.
I understand there is plenty of phosphate in the malt.
How come Ca++ doesn't react in its totality and some carries through?

Thanks
 
I fear there is no simple answer. Apatite precipitates when the products of powers of the concentrations of phosphate and calcium exceed a solubility product. Though we say malt releases a lot of inorganic 'phosphate' into the mash it really releases a lot of biphosphate (H2PO4-) ion as stated in #2. It is actually phosphate that coalesces with alium to form apatite. At any pH a percentage of the biphosphate converts to monophosphate and a fraction of that to phosphate. At pH 5.7 only 0.00000054% of the total phosphorous is in a PO4--- ion. If there is enough calcium around some will be pulled out as apatite and the released protons will lower the pH. Let's suppose it gets lowered to pH 5.4 at which 0.00000014% of the total phosphorous is in a PO4--- ion and of course that is a percentage of a reduced amount of phosporous as some precipitated with the calcium to supply the H+ that got us to 5.4. If the ion product of the reduced concentrations of calcium and phosphate are lower than the solubility product then the process stops. There can still be quite a bit of calcium and of biphosphate ion left at this point.
 
I fear there is no simple answer. Apatite precipitates when the products of powers of the concentrations of phosphate and calcium exceed a solubility product. Though we say malt releases a lot of inorganic 'phosphate' into the mash it really releases a lot of biphosphate (H2PO4-) ion as stated in #2. It is actually phosphate that coalesces with alium to form apatite. At any pH a percentage of the biphosphate converts to monophosphate and a fraction of that to phosphate. At pH 5.7 only 0.00000054% of the total phosphorous is in a PO4--- ion. If there is enough calcium around some will be pulled out as apatite and the released protons will lower the pH. Let's suppose it gets lowered to pH 5.4 at which 0.00000014% of the total phosphorous is in a PO4--- ion and of course that is a percentage of a reduced amount of phosporous as some precipitated with the calcium to supply the H+ that got us to 5.4. If the ion product of the reduced concentrations of calcium and phosphate are lower than the solubility product then the process stops. There can still be quite a bit of calcium and of biphosphate ion left at this point.

Although not simple, your answer does make sense, thanks for that.

So, if the amount of PO4-- is grist and pH dependant and the reaction with calcium also depends on the solubility product, what can be said about Kolbach equation for residual alkalinity? Brewing software seem to use it indistinctly of recipe and target pH.

I care about my kidneys ... What can I do to make sure all calcium oxalate precipitates? How can I know if I have sufficient calcium, having used 50-80 ppm Ca in mash water and <20ppm in the sparge water?

Two brews ago I got this residue in the bottles and I could not get an explanation on what it is (https://www.homebrewtalk.com/showthread.php?t=553708)

I have concluded it is beer stone so I worry.

bottle.jpg
 
Although not simple, your answer does make sense, thanks for that.

If you want more detail you can have a look at a paper I did for Cerevesia a few (several) years ago: http://wetnewf.org/pdfs/Brewing_articles/Cerevesia/Final_galley

So, if the amount of PO4-- is grist and pH dependant and the reaction with calcium also depends on the solubility product, what can be said about Kolbach equation for residual alkalinity?
It says that the Kolbach equation is fairly representative of what might be expected under nominal brewing conditions (or at least the nominal brewing conditions Kolbach was familiar with. The real reason for mentioning the Cerevesia article is that in the work leading up to it I simulated the full Monty and as I recall concluded that under the right (and not too unreasonable) conditions something like what Kolbach found was within the bounds of expectation.


Brewing software seem to use it indistinctly of recipe and target pH
A lot of people (including me and I translated Kolbach's paper) miss the fact that his calculation of pH depression is for knockout wort, not mash. In the mash the pH suppression is expected to be somewhat lower than what the spreadsheets calculate. Fortunately the calcium reaction is usually not responsible for a very big drop in pH unless you are doing one of these things with 750 ppm hardness that some guys seem to like.

I care about my kidneys ... What can I do to make sure all calcium oxalate precipitates? How can I know if I have sufficient calcium, having used 50-80 ppm Ca in mash water and <20ppm in the sparge water?
I think you are OK. If calcium oxalate is precipitating in your beer you would probably experience gushing. If you have a microscope at your disposal calcium oxalate crystals are pretty easy to spot.

Two brews ago I got this residue in the bottles and I could not get an explanation on what it is (https://www.homebrewtalk.com/showthread.php?t=553708)

I have concluded it is beer stone so I worry.
Beerstone is usually beige and attached to the walls of the container. Again the crystal structure of the material would be a clue as to whether it is beerstone.
 
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