[HopDen]

I did a step mash today as I often do. I checked the pH at 15 mins at 122* The pH was 5.15 I then checked at 30 mins still at 122* and pH was 5.26 After moving the temp to 152* and checking the pH, it was at 5.39 which was close enough to my target of 5.40

I am just curious as to WHY the pH starts out low and then rises to target pH after hitting high mash temp. It was 45 mins of mash time until I hit high temp.

Is pH temp specific?

Hypothetically speaking, if I never raised the temp past 122* would my pH still rise to my target of 5.40?

[denny]

Yes, it's temp specific if you don't cool the sample.  IIRC, Martin has said that it take around 40 min for pH to stabilize and it will settle around 5.4.  I hope someone will correct me if I'm misremembering.

[HopDen]

Ok, so to be clear, I do cool sample to 60*

[denny]

Ok, so to be clear, I do cool sample to 60*

Thought so, but wanted to be sure.  In that case I'd say the pH change is related to time, not temp.

[ynotbrusum]

So, how does that translate with respect to short mash/short boil methods?  Is there an adjustment that differs from a traditional 60 minute mash for a given grist?  Less acid, for example?  I wonder if the online calculators incorporate that in their systems?

[HopDen]

Ok, so to be clear, I do cool sample to 60*

Thought so, but wanted to be sure.  In that case I'd say the pH change is related to time, not temp.

I'm not certain that you understand what i'm asking, my apologies if you do.

Specifically, during step mash of 122* the pH measured 5.15 at 15 mins and then at the 30 min mark mash pH was 5.26
When I raised temp to 152* the pH measured 5.39 after 15 mins at that 152* temp.

I wanted to know why the pH was low at the lower mash temp of 122* and only when I raised the temp to 152* did the pH rise to 5.39

I hope this clarifies

[mabrungard]

Your observed pH response is very similar to a large suite of testing that I've performed and from most of my personal mashes. When acidified to produce a certain pH, the mash pH is often lower than target early and it rises during the mash. My data does show that it takes at least 45 minutes for pH to stabilize. 

I don't know the mechanism.  But I hypothesize that since strike water is acidified significantly for pale beers, the pH and alkalinity of that strike water are quite a bit lower than the targeted mash pH and the malt buffers that extreme pH back toward the target as the wort compounds are extracted from the grist.

[goose]

Yes, it's temp specific if you don't cool the sample.

Along the same line, if you  take a pH reading above room temperature, you will shorten the life of your probe.  I always cool the sample to below 80 degrees usually in the mid 70's.  I just replaced my probe a couple days ago after two years.  I normally would expect maybe one year for a probe but with care,  you can get more life out of it.

[roger]

It seems that if you no-sparge, this exaggerates the issue Martin is describing. More treated water equals more buffering capacity. Is this correct? Or does Bru'n Water account for this effect?

For example, my last mash was for a 4 srm hybrid. Using Bru'n Water, 2 ml of 88% Lactic acid in 8.25 gal. of water was needed to get the estimated mash pH to 5.4. As always, I took a sample at 15 minutes into the mash, cooled it, and it measured 4.8. The pH meter was calibrated earlier the same day. I assumed that the probe might be on its last legs, and just questioned the reading in my notes. But if it takes 45 minutes to reach its final pH, is there any value in measuring at 15 minutes?

[denny]

It seems that if you no-sparge, this exaggerates the issue Martin is describing. More treated water equals more buffering capacity. Is this correct? Or does Bru'n Water account for this effect?

For example, my last mash was for a 4 srm hybrid. Using Bru'n Water, 2 ml of 88% Lactic acid in 8.25 gal. of water was needed to get the estimated mash pH to 5.4. As always, I took a sample at 15 minutes into the mash, cooled it, and it measured 4.8. The pH meter was calibrated earlier the same day. I assumed that the probe might be on its last legs, and just questioned the reading in my notes. But if it takes 45 minutes to reach its final pH, is there any value in measuring at 15 minutes?

Doesn't seem like it, does it? 

[seolin]

Thank you!

I think this will solve my problem.

Best regards.

[narcout]

It seems that if you no-sparge, this exaggerates the issue Martin is describing. More treated water equals more buffering capacity. Is this correct? Or does Bru'n Water account for this effect?

For example, my last mash was for a 4 srm hybrid. Using Bru'n Water, 2 ml of 88% Lactic acid in 8.25 gal. of water was needed to get the estimated mash pH to 5.4. As always, I took a sample at 15 minutes into the mash, cooled it, and it measured 4.8. The pH meter was calibrated earlier the same day. I assumed that the probe might be on its last legs, and just questioned the reading in my notes.

That is a much larger variance between initial and target pH than I have ever seen in my no-sparge batches (and I take my initial readings 20 minutes into the mash). 

But if it takes 45 minutes to reach its final pH, is there any value in measuring at 15 minutes?

I think the answer depends in part on why you are targeting a certain mash pH.  For example, if the goal is to maximize ß-amylase activity, you'd want to consider that peak activity for that enzyme at a mash temperature of 67° C is around the 15 minute mark. 

[Big Monk]

Recirculation can play a huge role in pH stabilization as well. Most of the brewers I am interacting with these days either continuously or partially recirculate and see stabilization almost immediately.

I've seen the output graphs from Bryan's pH transmitters showing pH locking in directly after dough-in when recirculation starts and not moving the entire mash.

[roger]

I just realized, my post might have "hyjacked" seolin's original post. If so, accept my apology, that was not my intent.

And thanks to narcout, for providing some insight. I've never considered the concept of a moving mash pH.

I use a kettle RIMS system so the wort is constantly recirculated. I'll take 5-6 pH readings during my next batch to try to prove to myself what's happening.

Thanks again,