water adjustment vs boiloff rate

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shataway

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I need a simplified water adjustment answer.

I recently changed boil pots. The new one is much wider and my boil off rate has increased from 10% to 18%. When I use the EZ_water_adjustment spreadsheet, it has me increasing salts compare to the smaller pot. I realize this is because I am sparging with more water to account for the higher boil off rate. My gut tells me that this will leave more "residual" salts in the final product. Why is this not so?

Thanks,
Steven
 
I'm on board with your concern. I calculate the minerals for the mash and for whatever sparge water that makes it to the kettle. I've thought about the absolute correct way of calculating the mineral additions like you have. If you are going for a certain profile post boil, there are a couple more factors to keep in mind such as boil-off concentration and any minerals left behind in the grain after sparging.
Then, on the other hand, I want to try and keep it simple by just canceling out the boil-off rate and mash efficiency. There's only about a 5% difference on my system, 15% crap left in the mash (85% efficiency) minus 10% boil-off concentration. In my mind, I'm really ending up with 5% fewer minerals than I planned, if this logic is correct. That's not enough to over-complicate the calculations.
Nate
 
I did a little reading on howtobrew.com. It seems that some of the minerals or compounds may breakdown/boiloff/dropout as a result of the boil. My basic premis that the water boils off and leaves the "salts" behind may not be valid.

I still don't get it...
 
The basic idea is that if you were in a target city brewing and they have say 50ppm of sulfate in the water. When they brew and boil off 10% volume, they end up with 55ppm in the final wort. It's the same thing for us only we are adding salts to 50ppm preboil.
 
OK. I think you just agreed with my original post. Should I be adding salts based on boiling off 10% even though I know that I will sparge with more water based on boiling off 18%?
 
Simple answer: If I were you, I wouldn't add more minerals, especially if you liked the way your beer tasted with 10% boil-off. Maybe try an experiment?

Here's an e-mail exchange I had with JZ last year:

Jamil,
Is there a percentage of the minerals in the mash that get absorbed by the
grain? Calculating the kettle mineral addition depends highly on what
minerals actually make it to the kettle from the mash. Should I assume all
of the minerals make it to the kettle or only a percentage of them, similar
to the lautering efficiency percentage for sugars?

Do any of the common minerals (gypsum, chalk, baking soda, etc) boil-off?

John mentioned treating all the water, both mash and sparge water. It
doesn't seem he takes into account wort concentration during the boil. That would throw the entire profile off if you're looking for the same profile in
the finished beer as you had in the mash.

Thanks!
Nate

Nate,
I'm sure there is some chelation of the minerals in the mash, though
I'm not sure what percentage that would be. I don't think it would be
really high and some of the water gets locked up in the grain
material, so maybe the net result is higher, lower, or just the same.
I'm not sure I'd bother calculating it.

None of the minerals boil off. They might change form, depending on
the environment.

JZ
 
Well I thought I was done.

I am modifying my copy of the EZ spreadsheet for basic mash/sparge water volume calculations. Based on the above, I am using 10% for a standard boil off rate. In addition, I am using 1.25 qts/lbs of grain for mash water and 0.1g/lbs for grain absorbtion.

:mug:
 
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