Author Topic: Shift in thought regarding optimal mash pH  (Read 12035 times)

Offline narvin

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Re: Shift in thought regarding optimal mash pH
« Reply #15 on: August 08, 2012, 11:49:13 AM »
Cool photo.  Does that say 52.5 C?
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Re: Shift in thought regarding optimal mash pH
« Reply #16 on: August 08, 2012, 11:57:16 AM »
Cool photo.  Does that say 52.5 C?

52.5 degree Celsius = 126.5 degree Fahrenheit

So maybe they aren't waiting to cool it completely...

So remind me again why we measure at room temp and then do a conversion? Are pH meters significantly off at any higher or lower than room temp?
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Offline CB-Illinois

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Re: Shift in thought regarding optimal mash pH
« Reply #17 on: August 08, 2012, 12:24:52 PM »
Hi all,

I have used the pH meter Denny posted, and I can say with some certainty that the probe they are using is VERY sensitive and must be almost constantly in a buffer solution at room temp except when the probe is in the beer (and the beer must be at room temp also).

I have used probes that are designed to be much more robust and could measure solutions at high temps, but the readings were only for information (to make sure we were on track with pharmaceutical batch production).  When needed we would always cool a sample and take a reading at room temp for an actual in-process check.  I seem to remember the degree of error increasing quite a bit once a sampe was more than a few degrees above room temp.

Hope that helps.

Offline denny

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Re: Shift in thought regarding optimal mash pH
« Reply #18 on: August 08, 2012, 01:12:45 PM »
Cool photo.  Does that say 52.5 C?

52.5 degree Celsius = 126.5 degree Fahrenheit

So maybe they aren't waiting to cool it completely...

So remind me again why we measure at room temp and then do a conversion? Are pH meters significantly off at any higher or lower than room temp?

It sat there for quite a while and I'm pretty sure that it ended up at room temp.  Mike K., you out there?  Do you recall?
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Offline mrcceo

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Re: Shift in thought regarding optimal mash pH
« Reply #19 on: August 10, 2012, 12:03:01 PM »
I know this information is specific to my probe but thought it might prove useful in regards to this thread.

"The GK733526B electrode is rated for use from 0 - 100 °C.  That does not mean is should be continuously used at that kind of elevated temperature, but if you are doing grab samples, it should not be a problem.

Accuracy should not be affected if you are using it at an elevated temperature, but you should be using a temperature sensor on your pH meter for accuracy at those temperatures, and yes, for most accuracy, you should also have your calibration standards at 68 °C when calibrating.

Also, do not expect to see the same pH readings at 68C as you do at 25C.  I am not sure how your sample will respond to that kind of temperature change, but as an example, the pH 4 calibration buffer that reads 4.005 at 25C will read 4.116 at 70C; the pH 7 buffer that reads 7.000 at 25C will read 6.982 at 70C.

If you have any other questions, please let me know.

Thank you.

Sincerely,
Tim Schmitt
Technical Support
Hach Company

Offline weithman5

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Re: Shift in thought regarding optimal mash pH
« Reply #20 on: August 10, 2012, 12:43:19 PM »
so over a wide range 0f 25c-70c we are off by at most 0.116?
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Offline Kaiser

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Re: Shift in thought regarding optimal mash pH
« Reply #21 on: August 10, 2012, 12:53:04 PM »
so over a wide range 0f 25c-70c we are off by at most 0.116?

The temperature dependent pH shift that we are talking about here is dependent on the solution and is likely different between the buffer solutions mentioned in above statement and mash or wort. This is why we can't compensate for them universally. Aside from the fact that they are actual changes in pH.

Kai

Offline tomsawyer

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Re: Shift in thought regarding optimal mash pH
« Reply #22 on: August 10, 2012, 02:48:05 PM »
Also keep in mind that there is temperature compensation because of the difference in the electrical signal at different temps, and then theres temp changes in the solution that Kai is referring to.  When your meter has ATC (auto temp comp) it is only adjusting the readout based on temp.  Its not converting your reading to what it is at 68F.
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Offline weithman5

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Re: Shift in thought regarding optimal mash pH
« Reply #23 on: August 10, 2012, 03:09:04 PM »
yes, but if the meter can handle the temperature with good repeatability, an individual could make a small correlation table between mash temp ph and at room temperature ph.
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Offline nateo

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Re: Shift in thought regarding optimal mash pH
« Reply #24 on: August 10, 2012, 04:32:40 PM »
yes, but if the meter can handle the temperature with good repeatability, an individual could make a small correlation table between mash temp ph and at room temperature ph.

I don't think so, because it depends on the composition of the solution. I assume it's also related to water chemistry and wort gravity.
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Offline narvin

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Re: Shift in thought regarding optimal mash pH
« Reply #25 on: August 10, 2012, 05:08:32 PM »
yes, but if the meter can handle the temperature with good repeatability, an individual could make a small correlation table between mash temp ph and at room temperature ph.

I don't think so, because it depends on the composition of the solution. I assume it's also related to water chemistry and wort gravity.


Well, to be fair, the pH range of enzyme activity is measured at the temperature they are active, meaning they're measured at mash pH.  So we are making this correction when we measure wort pH at room temperature.
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Offline Kaiser

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Re: Shift in thought regarding optimal mash pH
« Reply #26 on: August 10, 2012, 07:04:14 PM »
I too think that the pH over temp curve will be fairly similar between wort samples.

Kai

Offline bluesman

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Shift in thought regarding optimal mash pH
« Reply #27 on: August 10, 2012, 09:40:15 PM »
I realize that ideal mash conditions are in the 5.2-5.7 range, but what is the real difference of a mash conducted at 5.2 vs. 5.6 in terms of beer flavor.  This would be a great experiment.  How does this effect mash efficiency or beer flavor.  I think Kai has conducted some experiments in this regard.  I've made excellent beers at both ends of the pH spectrum. Tannin extraction increases with increasing pH, but what can be said for a mash conducted on he higher side of the range?

This is an interesting mechanism that isn't clearly understood in terms of it's effect on the end product. I would like to see some further experimentation on the effects of mash pH on beer flavor.
Ron Price

Offline tomsawyer

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Re: Shift in thought regarding optimal mash pH
« Reply #28 on: August 11, 2012, 05:41:12 AM »
While we're discussing pH, why is the final pH of wheaqt beer so much loer than all-barley beer in spite of both starting at a similar mash pH?
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Offline Kaiser

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Re: Re: Shift in thought regarding optimal mash pH
« Reply #29 on: August 11, 2012, 06:40:55 AM »
While we're discussing pH, why is the final pH of wheaqt beer so much loer than all-barley beer in spite of both starting at a similar mash pH?

The more aggressive fermentation leads to a faster and larger pH drop. You can also observe this with different pitching rates: http://braukaiser.com/blog/blog/2012/06/21/pitching-rate-experiment-tasting/ look at pH over pitching rate.

Kai