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Does calcium carbonate stays as precipitate after pre-boiling?

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lupulus:
Dear homebrewers:
My first question/ post. I really look for this answer so please be forgiving if it is given somewhere else...
(I also sent this question to Kai but thought it may be interesting to see whether others asked themselves the same question)

I moved to Munich more than two years ago and as I brew mainly pale beers, I control the pH using acids, either lactic or citric, and a pH meter (sorry Reinheitsgebot).
The water profile in Munich is such that pre-boiling the water (before mashing) would lead to precipitation of most calcium (and magnesium?) and bicarbonate ions as calcium (and magnesium?) carbonate. Many brewers in Munich including many pros boil their water and then separate the water from the precipitate.
At the moment, I pre-boil water and separate it from the calcium carbonate precipitate. However, as I use the brew-in-a-bag method, to separate the calcium carbonate it would be more convenient for me to boil the water, have it cool down and have calcium carbonate precipitate, in the same kettle do the mashing then take the grains out boil the wort, cool it down (immersion chiller) and transfer all but the bottom residue to the fermenter. I reason that the calcium carbonate may continue to be in the bottom of the kettle throughout this process and is separated from the fermentable wort as calcium carbonate will stay with the trub in the bottom of the kettle.
In other words, my question is: Why german brewers separate the boiled water from the calcium carbonate precipitate, if you can leave the precipitate in the bottom (in brew in a bag) or leave it as a salt in a regular mash that eventually will settle as part of the trub after the normal boiling and cooling? Is it that the acidity of the mash and/ or boil will actually dissociate the calcium carbonate into ions and at least part of these ions will end up in the final beer, making it more "chalky" that it would be otherwise.

Thanks for reading and I would appreciate any comments  :)



mabrungard:

--- Quote from: lupulus on June 22, 2013, 01:35:46 AM ---
In other words, my question is: Why german brewers separate the boiled water from the calcium carbonate precipitate, if you can leave the precipitate in the bottom (in brew in a bag) or leave it as a salt in a regular mash that eventually will settle as part of the trub after the normal boiling and cooling? Is it that the acidity of the mash and/ or boil will actually dissociate the calcium carbonate into ions and at least part of these ions will end up in the final beer, making it more "chalky" that it would be otherwise.

Thanks for reading and I would appreciate any comments  :)

--- End quote ---

Damn straight, sorry Reinheitsgebot!  That archaic rule will keep German beer from exploring and growing.  I'm glad to hear that you are not following it.

Munich water has huge alkalinity (aka: temporary hardness) and the boiling treatment is quite effective in removing a portion of the calcium and bicarbonate from solution and depositing it as chalk in the boil pot. 

If that chalk in contact with the original water, some of it would eventually go back into solution as CO2 is reabsorbed into the water from the atmosphere to form carbonic acid.  However in the mash, boil, and ferment, stronger acids than carbonic acid are formed and they will eventually react with that chalk also.  You may not think that is a problem, but we have to remember that a proper level of acidity is a necessary component of beer flavor.  Flabby or dull flavor is often cited in that case.  In addition, if the wort pH in the kettle is a few tenths higher than typical, the hop bittering and flavor can get more harsh. 

One thing that I've noted and Kai has proven, is that there are apparently a small quantity of strong acids produced in the mash.  Those are acids stronger than the phytin-derived acids of the mash and they probably consist of acetic and lactic acids.  Those stronger acids will rapidly react with chalk and will get neutralized.  Once neutralized, those acids aren't there to contribute to the acid balance desired in our beers.  So removing the chalk from the rest of the treated water is an important step in ultimately maintaining the desired acidity and flavor expected in beer. 

Sure, you could just add extra acid to the water or wort to make up for the losses created by the chalk.  But then you would be back at original water and just adding acid to neutralize the tap water's alkalinity.  That is OK, but the acidification would add whatever anion from the acid (orthophosphate, lactate, chloride, sulfate, etc. depending upon the acid used). 

Attendees at the NHC in Philly next week will get additional insight into working with Munich water by hauling their butts out of bed on Saturday to see my presentation on Historic Water.  I look forward to seeing you there.

denny:
I'll be there...I'm introducing you!

hopfenundmalz:
My sorry old butt will be in a chair for this one.

joe_feist:
Great question and I really enjoyed the answer. Planning to brew a Munich or Vienna next and I typically boil my water for the same reasons as the OP. I won't be in Philly, Martin, but will your presentation be on the AHA website afterwards?

I'm planning on being at the NHC in GR next year. 'Specially since I live 15 mins from the venue.

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