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
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.