Boil-off rate and water chemistry

[The_Glue]

During a 90 min boil, about 50% of my water can evaporate. So in by the end of the boil i end up with twice the minerals in my water. Is this something i should take care of when building my water profile? For example my tapwater have 40-50ppm Magnesium in it by default. That will creep up too high by the end of the boil i guess.

 

[sandyeggoxj]

I would look at why you are boiling off so much. What size kettle and how wide is the top? Are you propane/NG fired or electric?

You must have a very aggressive boil going on. Do you see these boil-off rates year round? Depending on your setup you could boil a little less vigorously and be okay I would bet. You just need enough to push out dms and such.

I don't know all the answers in terms of water chemistry. I would guess that if your mash and sparge pH is on track and your residual alkalinity all tracks okay then you are likely okay on the boil chemistry. I would figure out why you are boiling off so much in such a short period of time before worrying about boil chemistry.

One last question: have you tested the pH of your finished beer?

 

[char005]

I agree that boil off rate is extremely high. Proabably too high. Try dialing it back to about 15% an hour if you can. Probably have alot of malliard reaction going on with a boil that intense. Calcium and the magnesium you mentioned are more of a concern in the mash rather than the boil. They will affect your pH and alkalinity. The flavor minerals that you should be concerned about primarily are chlorides and sulfides.

 

[afr0byte]

I agree that boil off rate is extremely high. Proabably too high. Try dialing it back to about 15% an hour if you can. Probably have alot of malliard reaction going on with a boil that intense. Calcium and the magnesium you mentioned are more of a concern in the mash rather than the boil. They will affect your pH and alkalinity. The flavor minerals that you should be concerned about primarily are chlorides and sulfides.

*sulfates

 

[The_Glue]

I used a small SS pot on an electric stovetop brewing 1 gal batches but in the close future i will move on to propane and a 5 gal SS pot. I think one of the reasons my boil off was too high is that my pot could barely hold more water than my goal amount so i topped off a lot during the boil. Also my kitchen went sucked in the steam pretty strong.
My main concern was that Palmer said

amounts greater than 50 ppm tend to give a sour-bitter taste to the beer

about magnesium.

I have not measured final ph but my other minerals would be still in the proper range even if they were doubled by the boil.

 

[ajdelange]

There are two goals in mineral adjustments to brewing water. One is assistance in establishing mash pH (the minerals are secondary there) and the other is flavor. Concentration of minerals from unusually high water loss in the boil is more of a factor in the second department than the first but removing a lot of water may concentrate calcium and malt phosphate to the point where they will jointly precipitate thus lowering wort pH more than normal.

Of course the big question is as to whether you extract is coming out where you want it. If not, you could add 'makeup' water as the boil progresses (though I think you should probably turn down the heat to the point where the more traditional 10%/hr evaporation takes place.