mash pH sample the day after

[wapitiscat]

I brewed a 3 Floyds Alpha King clone this weekend and have a question about mash pH. I'm using a MW-102 meter and took my sample about 15' into the mash after a quick stir and temp check (154 F). Since I was itching to make any necessary adjustments, I went ahead and check the pH (with the temp probe in the mix) and was surprised to see a reading of 5.01. I figured I must have botched my calibration or the temp correction wasn't working so I just let it ride and finished the mash. I decided to let that sample cool and took it inside and covered it with an inverted glass. Well, I forgot about it and didn't get around to measuring it until the next morning. Recalibrated and got a reading of 5.33. The estimated SRM for the recipe is 11 and the RA of my water was calculated as 22 ppm (BeerSmith). Estimated mash pH was 5.48 in Bru'n Water and 5.55 in BS.

Is this still a good representation of what my mash pH was the day before? Or were there pH altering processes going on during the delay?

Todd

 

[acidrain]

154F is dangerously close the the max temp of that meter.
I suspect that the temp had something to do with it. Try cooling a sample next time and see if it as predicted.

 

[ajdelange]

The temperature definitely has something to do with it even with ATC. Mash pH rises with increasing temperature. 0.3 pH is an unusually large increase, however.

Also mash that is not carried through the remainder of the process is going to exhibit a drop in pH as the lactobacilli on the grain will start to grow. Perhaps just overnight and at room (as opposed to the elevated temperatures lactos like) you are OK but that should be taken into consideration.

In the future take pH readings at room temperature. See the Sticky at Brewing Science for tips on how to use your meter.

 

[wapitiscat]

OK. So I'm thinking I should probably assume that the "true" mash pH was higher (closer to the two estimates) and not in the sweet spot for this style.

I'm pretty comfortable using a pH meter but not in the context of a solo brewday. I was not very organized and was rushing in anticipation of adjusting the pH with lactic acid. It seems that allowing the sample to cool to room temp precludes on the fly pH adjustment. Do most folks just collect these data as reference points for the next time they brew that recipe? Use them to sort of get comfortable with an estimated mash pH calculation and make a pH tweak from there to get closer to a target pH?

acidrains comment sounds right as I have seen that 5.01 value pop up before when testing previous samples at higher than room temps. I guess it could be the meters way of telling me I'm abusing my probe.

Todd

 

[jekeane]

If you are taking a shot glass size sample for ph. Just put it in a small ice bath and it is cool in less than 5 minutes.

 

[day_trippr]

[...]Do most folks just collect these data as reference points for the next time they brew that recipe? Use them to sort of get comfortable with an estimated mash pH calculation and make a pH tweak from there to get closer to a target pH?[...]

That'd be a reasonable summation of my practice, at least wrt mash ph.
I rarely brew away from home, I've used Bru'n water with my well water for long enough to be comfortable with its adjustments, but I'll still take measurements of mash ~10 minutes in, and I'll check the sparge well before it's needed. I record them both to Beer Smith with whatever comments needed.

I use a 4 ounce straight-sided Sam Adams beer tour glass with enough wort or sparge water to definitely cover the pH meter sensor, stood up in a cereal bowl filled with ice cubes and water. It's tall enough to keep my Hanna handheld from falling over.

Takes a couple of minutes stirring to get the sample down to a comfortable temperature before using the meter. If there was something that needed to be done as a result of the testing there'd likely be enough time to have the desired effect (certainly with the sparge liquor)...

Cheers!