Ph rise after mash in

[silobran]

Hi,
First of all i have calibrated my ph meter every time before use, second i lowered ph of strike water with lactic acid from 7.8 to 6.5 which resulted in mash ph 5.9. Next time i added a bit more acid, ph was 5.8. I kept adding more acid till i reached 5.3 which was good enough for me. Next brew i added same amount of acid to strike water. After mashing in(after 30min) i measured mash ph and it was 5.3. i saved a sample of acidified strike water which had ph of 4.2. Thought i made a mistake, so i measured again next time brewed and ph result were the same.

Is this normal? As far as i understand mash ph the grain should lower ph not raise it.

 

[mashdar]

Mash (and most organic systems) have a ton of buffers that absorb or give off H+ around one particular pH or another. Determining equilibrium is actually an entire semester of "analitical chemistry" in college!

While strike water of 4.2 seems a little low, that it rose with addition of grain is not surprising.

(edit: and if strike pH that low works, then roll with it. I actually don't measure strike pH, so I may just be clueless. Do you measure pH 15m into mash? That's generally considered best practice 'round these parts.)

 

[silobran]

I usualy measure 30+ min into mashing.

 

[mashdar]

Oh, that's fine. As long as it's not right away!