Inconsistent acid malt

[JonM]

So I had this very thing happen to me this morning:

https://www.homebrewtalk.com/showthread.php?t=539529

What's weird is two months ago, I made a Bohemian Pils with a little over 10 lbs of Pilsner and 5 oz of acid malt. pH was something like 5.48 or something.

I made a Patersbier this morning with the exact same grain bill purchased from the same LHBS, except I wanted to bring that pH down a touch more, so I got 6 oz of acid malt. Mash pH was 4.8. Cripes. I added some calcium hydroxide and got the pH up to 5.4something, and confirmed it with multiple checks later in the process. Everything will be fine, but what a pain in the butt.

Anyway, I'm going to be using lactic or phosphoric from now on.

 

[ajdelange]

What's weird is two months ago, I made a Bohemian Pils with a little over 10 lbs of Pilsner and 5 oz of acid malt. pH was something like 5.48 or something.

Using 5 Oz Weyermann's sauermalz with 11 lbs of their pneumatic pilsner malt should get you a pH of 5.48 if the alkalinity of the water (4 gal) was 1.34 mEq/L (67 PPM AS CaCO3).

I made a Patersbier this morning with the exact same grain bill purchased from the same LHBS, except I wanted to bring that pH down a touch more, so I got 6 oz of acid malt. Mash pH was 4.8. Cripes.

Indeed! That would require an additional 221 mEq of protons (equivalent to 19.2 mL of 88% lactic acid liquid) beyond what we would expect from 6 Oz sauermalz. That is, it would have to deliver 5 times more acid than measurements on it say it does.

Anyway, I'm going to be using lactic or phosphoric from now on.

Something certainly isn't kosher here but it's interesting that you have assumed it is the sauermalz. In a case like this my suspicions would turn to the pH measurements. I'd want to do some checks on the sauermalz. Grind up an Oz of it and add it to a half liter or so of DI water and add sodium bicarbonate until pH 5.64 is reached. Normal (what Kai and I measured) sauermalz should require about 1 gram. If you find it takes 5 grams then you have super sauermalz (5X!) strong enough to explain what you observed.

I added some calcium hydroxide and got the pH up to 5.4something, and confirmed it with multiple checks later in the process. Everything will be fine, but what a pain in the butt.

If you do have 5X sauermalz then you did the right thing but if the problem is with the PH readings you didn't. Best check the pH meter before doing any thing else.

 

[JonM]

Thanks for your input, as always, AJ. I was totally puzzled by all this this morning. I pulled a second sample after the first weird reading and it was the same. My first thought was that the meter was screwy (it was calibrated, 2 points) so I grabbed the 4 buffer solution just to see what it read, (before making any adjustments) and it was spot on. Very strange.

 

[ajdelange]

My first thought was that the meter was screwy (it was calibrated, 2 points) so I grabbed the 4 buffer solution just to see what it read, (before making any adjustments) and it was spot on.

That's the right way to think for sure.

Very strange.

I certainly is. You have 19 ml of lactic acid you can't account for other than to assume it is 5X acidulated malt. Do you have any left for a bicarbonate test?

 

[JonM]

Nope, all out. Maybe the LHBS still has the same stuff. If I'm over in that part of town I'll grab some more.