We know that when added to the mash, Calcium reacts with phosphates (from the grains) and precipitates out as insoluble calcium phosphate. What I'm wondering is how much calcium would typically be 'used up' in this way and therefore not be available by the time everything gets to the fermenter. I think I've heard Palmer say that you can pretty much assume that any salts added to the mash will make it to the kettle. But in Gordon Strongs' book, he says 'most of it is lost during lautering' when discussing calcium. I'm not sure if he means 'lost' because it has been changed into calcium phosphate (which would really be a loss as a result of the mash, not the lauter), or if he meant that it physically remains in the grain bed, which doesn't make much sense to me. Anyone know for sure?
I've always wondered the same thing...and added 1/2 of mash addition to boil unless using copious amounts of gypsum in boil. Awaiting scientific response : )
According to george fix's principles of brewing science, it takes anywhere from 5-7 parts of calcium to create 2 parts of hydrogen. Since it takes 3 calcium ions to create 2 hydrogen ions, this means that 3 in 5-7 or 40-60% of calcium ions are used up in this reaction. I assume it also depends on the phosphate concentration.
I was going to say that the research suggests that the mash actually contributes 30ppm calcium to your wort from grain. 80ppm has been cited at a standard target in finished wort, so it's then said that you should get a minimum of 50ppm in your brewing liquor. Never seen a credible source cite the mash reducing calcium. Not saying that it does't exist, but that's what they are teaching in school these days...
Might have that a bit off in that you want 80ppm in your mash, and that will be reduced, but you will initially get 30ppm from your malt on average, so you want you liquor to have at least 50ppm.
