Measuring Mash pH

RichardM · Dec 31, 2024

The following is from "Brewing Better Beer" by Gordon Strong, a Christmas present

This is the first time I have seen this. I thought the advice was always to cool the wort. What do you think?

Caramel Ox · Dec 31, 2024

This is from John Palmer in the water book:

Sadfield · Dec 31, 2024

My reading of this is, Gordon is a moron for encouraging the unnecessary sticking a pH meter into a hot mash, when he knows the degree of correction for temperature. And Palmer, isn't stating whether he's making a correction or aiming for 5.2 to 5.5 at 20°c or 65°c.

You either want the higher range at room temperature or lower range at mash temp. Simple.

Using strips at 20°c is easy as you only need to cool a teaspoon of wort to 20°c. Using a probe at 65°c will shorten it's lifespan.

Sadfield · Dec 31, 2024

View attachment 107591 View attachment 107588

My reading of this is, Gordon is a moron for encouraging the unnecessary sticking a pH meter into a hot mash, when he knows the degree of correction for temperature. And Palmer, isn't stating whether he's making a correction or aiming for 5.2 to 5.5 at 20°c or 65°c.

You either want the higher range at lower temperature or lower range at mash temp. Simple

Using strips at 20°c is easy as you only need to cool a teaspoon of wort to 20°c. Using a probe at 65°c will shorten it's lifespan.

Caramel Ox · Jan 1, 2025

Palmer is definitely saying 5.2 to 5.6 at 20 degrees. No citation though which is a shame as many parts of the book have one.

Leon103 · Jan 1, 2025

Just get a meter that auto corrects at any temperature

RichardM · Jan 1, 2025

Leon103 said:
Just get a meter that auto corrects at any temperature

That would show you the pH of mash but the point is that pH changes with temperature and Stong says it should be 5.2 to 5.5 at mash temp but Palmer says 5.2 to 5.6 at room temp. They can't both be right.

The Baron · Jan 1, 2025

One votes Labour the other Conservative :coat:

This is the problem with experts one brewer reads their comments and another reads the others and causes contradiction in methods.
Ps Dry hopping does not add IBU's/Bitterness???
My opinion as a EXPERT is it makes beer more bitter :laugh8:

Sadfield · Jan 1, 2025

Leon103 said:
Just get a meter that auto corrects at any temperature

That won't help.

ATC adjusts for how the probe output voltage changes at temperature. The change in pH due to the chemistry of the mash at temperature, will still exist.

Caramel Ox · Jan 1, 2025

This is what Brewfather has to say, of course we don’t know the source either, but at least we know what the software is predicting.

Sadfield · Jan 1, 2025

The above, from Principles of Brewing Science by George Fix, Phd, shows that Amylase activity is highest at 5.2pH at 60°C.

As can be seen, going above 5.2pH at mash temperature has a greater detriment to enzyme activity than being too acidic. So, although aiming for 5.2 at mash temperature is correct, aiming for 5.2 at 20°C would result in a pH in the mash of 48.5. Giving a bit of a safety net, being better to be too low, than too high. This may explain the discrepancy between academic publications and those from hobbiest brewers.

Appleton Brews · Jan 1, 2025

Although I’ve got a cheap pH meter I’ve never used it. I use the value predicted by Brewfather and I aim for 5.4.

Caramel Ox · Jan 1, 2025

This from Braukaiser here https://braukaiser.com/wiki/index.php/How_pH_affects_brewing

Lots of detail including that the measured pH difference was found to be only 0.2 between the 2 temperatures when tested.

5.4 at room temperature still seems to be fairly safe ground.

peebee · Jan 1, 2025

RichardM said:
That would show you the pH of mash but the point is that pH changes with temperature and Stong says it should be 5.2 to 5.5 at mash temp but Palmer says 5.2 to 5.6 at room temp. They can't both be right.

They can both be wrong though!

But I'd go with Palmer ... simply because sticking a sensitive and fragile probe in hot wort will soon break it. It might only crack and start reading erratically? And you might not notice (or think "ah... it'll be alright").

Papers/strips won't break. You can use them as instructed (the manufacturer will specify a working temperature) and ignore both of them. That'll sort it? Indicators not sensitive enough? But you have no idea what you're trying to measure and no idea how accurate you need to (or can) be. Neither Palmer nor Strong try to tell you that!

RichardM · Jan 1, 2025

peebee said:
They can both be wrong though!

But I'd go with Palmer ... simply because sticking a sensitive and fragile probe in hot wort will soon break it. It might only crack and start reading erratically? And you might not notice (or think "ah... it'll be alright").

Papers/strips won't break. You can use them as instructed (the manufacturer will specify a working temperature) and ignore both of them. That'll sort it? Indicators not sensitive enough? But you have no idea what you're trying to measure and no idea how accurate you need to (or can) be. Neither Palmer nor Strong try to tell you that!

I use RO water and Bru'n Water to work out what brewing salts to add and then don't bother checking mash pH

Measuring Mash pH

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