Mash pH

[PlinyTheMiddleAged]

All,

I thought I had these water additions and pH figured out - at least conceptually. Thanks to Bru'n Water, I can select my starting water profile (distilled), enter my grain bill, select my target profile, and add salts to approach the target while keeping a close eye on estimated mash pH.

I've been doing that for my last several brews and have ended up with much better beers. In all cases, I've targeted a mash pH of 5.4, and I've gotten really close to that. Perfect, right?

So, then I run across this video of a Q&A session with the head brewer from The Alchemist.
[ame]http://youtu.be/LdfySDN2mF0[/ame]
Watch between 42:00 and 45:00 minutes for Kimmich's thoughts on mash pH. He says that the mash pH should be between 5.1 and 5.3. If you get all the way up to 5.4 you'll end up with a real muddled hop flavor to your beer.

What do all of you think? Maybe what I should do (after my fermentation chamber empties out) is brew a few small batches at different mash pH values to see how the hop expression changes.

Do you think he's talking pH at mash temperatures and we look at pH at room temp? Seems like a big difference between what I read as standard practice and what he supposedly uses for Heady Topper.

Thanks for reading.


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[bob1852]

He says that the mash pH should be between 5.1 and 5.3. If you get all the way up to 5.4 you'll end up with a real muddled hop flavor to your beer.

[snip]

Do you think he's talking pH at mash temperatures and we look at pH at room temp? Seems like a big difference between what I read as standard practice and what he supposedly uses for Heady Topper.

Yeah, one would think he's talking actual mash temperature pH, while we (mostly) refer to room temperature pH.

The difference is roughly ~0.3 units, so his pH of 5.1 to 5.3 at mash temperature would be our 5.4 to 5.6 at room temp.

 

[mtnagel]

I also asked about this in the Heady Topper thread and didn't really get a satisfactory answer. Hopefully you will.

I've also heard Martin say:

To help bring out the hopping and bitterness, it is important to keep the wort pH around 5.4. If the pH is much lower than that, the hop expression will be muted.

So I'd love to get to the bottom of this. The obvious answer is to experiment, but if others have done the work, I'd love to hear what they have to say too.

 

[ajdelange]

Clearly mash pH has little direct effect on hops utilization which is controlled by kettle pH. There are good reasons for having mash pH in the region around 5.4 but it seems to be though desirable to have kettle pH around 5.2 and many brewers add acid or salt to insure that if they don't hit it naturally.

Hops acids are like many others. The anion is more soluble than the acid so that the higher the pH the more gets dissolved. If getting the BU you paid for is the main driver then keep kettle pH high. If the best beer is desired then keep kettle pH lower and use more hops to attain the same level of bitterness. It's been said here than experimentation is what is called for and that is what you will have to do to find out what works best for you.

 

[PlinyTheMiddleAged]

Well, I guess I'll volunteer to brew some small batches of IPA at different pH levels. Here's my proposal - two one gallon batches; one at 5.4 and the second at 5.2. I'll use the recipe for Two Hearted (found here in the Recipes forum) since it is a fairly straightforward brew. Thoughts on the starting point?

The results though are many weeks away - I'm probably 3 weeks away from brewing due to a combination of a full fermentation chamber and out of town business. That puts the results of this experiment about 2 months away.

Of course, others are welcome to independently perform a similar experiment in the mean time using whatever recipe they deem appropriate.

I'll report back with my (purely subjective) results. But I will say upfront that what I am after is a hop flavor that is really highlighted.

Thanks! And comments/suggestions are welcome.



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[mtnagel]

Clearly mash pH has little direct effect on hops utilization which is controlled by kettle pH. There are good reasons for having mash pH in the region around 5.4 but it seems to be though desirable to have kettle pH around 5.2 and many brewers add acid or salt to insure that if they don't hit it naturally.

Are you suggesting that you adjust the pH after the mash but before the boil? Or are you saying that you just have to pick which one you care more about and use that for your mash pH which carries over into your kettle pH?

Well, I guess I'll volunteer to brew some small batches of IPA at different pH levels. Here's my proposal - two one gallon batches; one at 5.4 and the second at 5.2. I'll use the recipe for Two Hearted (found here in the Recipes forum) since it is a fairly straightforward brew. Thoughts on the starting point?

The results though are many weeks away - I'm probably 3 weeks away from brewing due to a combination of a full fermentation chamber and out of town business. That puts the results of this experiment about 2 months away.

Of course, others are welcome to independently perform a similar experiment in the mean time using whatever recipe they deem appropriate.

I'll report back with my (purely subjective) results. But I will say upfront that what I am after is a hop flavor that is really highlighted.

Thanks! And comments/suggestions are welcome.

Thanks for agreeing to test it out! Although, I my gut says it will probably be tough to see a difference in those pH levels, but I'd love to be proven wrong!

If it were trivial to add legs, I'd probably like to test a leg where pH isn't adjusted (with my water and mineral additions I did when I made the Bell's Two Hearted, Bru'n Water predicts I'd get 5.69; I wasn't measuring pH when I make this batch last year, so I don't know how accurate that is). I'd also test what Bru'n Water says is optimum, 5.4, and a low point just to see what that does, so maybe 5.1. Of course it's not trivial to add legs though and you have to worry about variability in making too. But I would never dissuade anyone from experimental testing, I'd love to hear what you get!

 

[ajdelange]

Watch between 42:00 and 45:00 minutes for Kimmich's thoughts on mash pH. He says that the mash pH should be between 5.1 and 5.3. If you get all the way up to 5.4 you'll end up with a real muddled hop flavor to your beer.

I guess I should have listened to this before I posted. I finally did so and he isn't saying anything about hops here. He is referring to the fact that high mash pH leads to overall dull flavors in the beer and this is quite true. At lower mash pH all the 'flavors become brighter' as someone here pointed out. But these are the malt related flavors. The hops flavor qualities are controlled, as discussed earlier, by kettle conditions - not mash conditions.

 

[CUrchin]

I guess I should have listened to this before I posted. I finally did so and he isn't saying anything about hops here. He is referring to the fact that high mash pH leads to overall dull flavors in the beer and this is quite true. At lower mash pH all the 'flavors become brighter' as someone here pointed out. But these are the malt related flavors. The hops flavor qualities are controlled, as discussed earlier, by kettle conditions - not mash conditions.

That is very helpful to understand, thank you. Since he only brews one beer, do you think he is using mash ph as a predictor of kettle ph?

After listening to that talk it is very clear to me the reason Heady is so good is that he really has perfected every part of the process and insists on using the finast ingredients - So my guess is he controls the ph at each and every step.

 

[PlinyTheMiddleAged]

I guess I should have listened to this before I posted. I finally did so and he isn't saying anything about hops here. He is referring to the fact that high mash pH leads to overall dull flavors in the beer and this is quite true. At lower mash pH all the 'flavors become brighter' as someone here pointed out. But these are the malt related flavors. The hops flavor qualities are controlled, as discussed earlier, by kettle conditions - not mash conditions.

Well he's definitely talking mash pH. And you are correct, I misinterpreted his statement about "brightness" - he was addressing the overall beer flavor and not simply the hop expression.

I think this is still worth taking a closer look. Unless someone has a better idea (and the logic to back it up), I'll try brewing two small batches with one mash being more acidic - the first will be 5.4 and the second 5.2. I'll also measure the kettle pH when the boil is done.

I'll report my results back here followed by the tasting results.




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[ajdelange]

Usually if mash pH is proper kettle pH will be too but that is not always the case and it may turn out that one can improve the beer by adjusting kettle pH to some other value than that to which it naturally goes when mash pH is proper. We tend to say 'get the mash pH to 5.2 - 5.5 and the kettle pH to 5.0 - 5.3 and all will be beer and skittles' but that is not to say that there isn't an optimum mash pH and an optimum kettle pH somewhere in those ranges. The only way to find that out is to experiment. A guy brewing the same beer over and over again (the ultimate case being a guy that brews only one beer) can make lots and lots of tiny tweaks over hundreds of batches and wind up with pretty close to the optimum and I'm guessing that this guy has done that for both mash and kettle pH.

 

[PlinyTheMiddleAged]

Usually if mash pH is proper kettle pH will be too but that is not always the case and it may turn out that one can improve the beer by adjusting kettle pH to some other value than that to which it naturally goes when mash pH is proper. We tend to say 'get the mash pH to 5.2 - 5.5 and the kettle pH to 5.0 - 5.3 and all will be beer and skittles' but that is not to say that there isn't an optimum mash pH and an optimum kettle pH somewhere in those ranges. The only way to find that out is to experiment. A guy brewing the same beer over and over again (the ultimate case being a guy that brews only one beer) can make lots and lots of tiny tweaks over hundreds of batches and wind up with pretty close to the optimum and I'm guessing that this guy has done that for both mash and kettle pH.

Absolutely. That's why I will also measure kettle pH. Although during this first round of experimentation, I don't intend to target a particular kettle pH, I will get data to show how mash pH leads to kettle pH (but I'm guessing someone versed in chemistry such as yourself could probably make a pretty good guess based on water, salts, grist, and boil-off rate).

Another experiment would be to split a single mash and adjust the kettle pH prior to starting the boil to see how that effects hop expression and overall beer flavor. Maybe next round.


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[bob1852]

Post mash pH is usually ~5.4, but I don't acidfiy my sparge enough so it is often 5.6-5.8 resulting in a kettle pH of ~5.5-5.6 preboil and ~5.4-5.5 post boil (numbers are off the top of my head without looking at my data but I know kettle pH isn't ~5.2).

Guessing I should acidify my sparge water more so that kettle pH is closer to ~5.2?

 

[PlinyTheMiddleAged]

Well, you've already got more data than me - I've got zero kettle pH information. I simply measure mash pH and target 5.4 (which according to my pH meter, I get within a hundredth or two points). Once mash is complete, I drain and sparge (without acidifying my sparge water - I use distilled with other salts added but no carbonates).

As a result, I know my mash pH but not my sparge and kettle pH. I figured once my mash was done, my pH concerns are over.

So, I'll start watching kettle pH as well


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[mtnagel]

I'm curious why you guys aren't acidifying your sparge water? Lately I've been doing BIAB, but with a dunk sparge step. I use Bru'n Water and it tells me to acidify my sparge water, so I have been. But I've only been measuring mash pH, confirming I'm at target or adjusting as necessary and then measuring until target and then not measuring again.

 

[bob1852]

Well, you've already got more data than me - I've got zero kettle pH information. I simply measure mash pH and target 5.4 (which according to my pH meter, I get within a hundredth or two points). Once mash is complete, I drain and sparge (without acidifying my sparge water - I use distilled with other salts added but no carbonates).

As a result, I know my mash pH but not my sparge and kettle pH. I figured once my mash was done, my pH concerns are over.

So, I'll start watching kettle pH as well


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Since I'm saving pre and post boil samples for a refractomerer reading anyway, it's not much extra time to take another pH reading.

I'm curious why you guys aren't acidifying your sparge water? Lately I've been doing BIAB, but with a dunk sparge step. I use Bru'n Water and it tells me to acidify my sparge water, so I have been. But I've only been measuring mash pH, confirming I'm at target or adjusting as necessary and then measuring until target and then not measuring again.

I am acidifying sparge water. Just not enough, apparently.

 

[PlinyTheMiddleAged]

I'm not acidifying sparge water for two reasons:

1) I'm starting with distilled water, so there is no buffering capacity to my sparge water. The pH goes to where the grain takes it. Thus far, I have just assumed it was acceptable; however, I should check just to be sure.

2) I'm lazy.

Mostly 2 though. I will say though, that even with an IPA grist, I have to add a very small amount of baking soda or lime to get my mash up to 5.4.

On my last IPA (Two Hearted), according to Bru'n Water, my water and grist alone (zero acidulated malt) got me to a mash pH of 5.62. With gypsum, Epsom salt, canning salt, and calcium chloride, I would be at 5.31. Adding 0.17 grams of baking soda (I couldn't find lime anywhere) per gallon of strike water used got me to 5.40. Since I treat my strike and sparge water the same (except for the baking soda) I think I am using slightly acidic water as a result of my other salt additions (they are knocking the pH down by 0.3 - from what to what, I don't know. See #2 above.). Plus I brew in a bag and dunk sparge, so I'm really lazy. But, just for the sake of the proposed experiment, I'll measure and record pH at several points including sparge.

Finally, to get down to 5.2, I'll skip the baking soda and substitute in 1% acidulated malt for the Two Row in my Two Hearted grist. Yes, that will change the sodium ions as well, so I'll have to think about that. But it does seem silly to add bicarbonate just so I can knock them down with acid.



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[Calichusetts]

Rocking a really light IPA this weekend with an intended mash pH of 5.2 after I watched the video last week. I'll let you know what happens in a month or so. A little worried that my acid malt is getting over 2% in this but we'll see how it goes.

 

[PlinyTheMiddleAged]

Cali,

Sounds good. I assume this is a recipe you have brewed previously? Do you generally shoot for a mash pH of 5.4? Do you measure pH with a meter or just go with grist and water models tell you (which in my limited experience with Bru'n Water is pretty good)?

Looking forward to hearing your thoughts on how this beer develops. I can't wait until my next brew day, but like I said earlier, it's several weeks away.




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[Calichusetts]

Cali,

Sounds good. I assume this is a recipe you have brewed previously? Do you generally shoot for a mash pH of 5.4? Do you measure pH with a meter or just go with grist and water models tell you (which in my limited experience with Bru'n Water is pretty good)?

Looking forward to hearing your thoughts on how this beer develops. I can't wait until my next brew day, but like I said earlier, it's several weeks away.

Yes it is, Galaxy hop IPA. This recipe usually comes in at 5.4 on the button so I just added acid malt to get me to 4.19 predicted. I really like brewers friend software for water calculations. I'm sure bru'n is great and I've looked at it. Just not a layout I really enjoy. I go peak it it every month or so but BF is just so nice visually.

 

[Veedo]

The same questions popped into my mind when I watched the video. I will be brewing tomorrow so I'll take a pre and post boil pH reading.

 

[Veedo]

Brewed tasty mcdoles session pale ale.

Mash pH @15 = 5.45
Pre boil pH = 5.34
Post boil pH = 5.3

I kind of thought the post boil pH would have been lower, but this is the firs time I've measured it. Thoughts?

 

[ajdelange]

I too would have expected a bit more of a drop in the kettle but believe that 5.3 is adequately low. My sense of what is proper kettle pH isn't nearly as refined as my sense of what is proper mash pH, however.

 

[Veedo]

I too would have expected a bit more of a drop in the kettle but believe that 5.3 is adequately low. My sense of what is proper kettle pH isn't nearly as refined as my sense of what is proper mash pH, however.

I will keep checking it over the next few brews. I am using split 50-50 DI water with ground water for a bicarbonate ppm of around 45. for this beer we targeted moshers pale ale water profile, with 1ml lactic acid addition. my mash is a bit different, we did a full volume no sparge mash, not sure if that would have an effect on final ph. I will also measure the ph of the final beer.

 

[zwiller]

Decided to sign up to respond to this thread.

I have made quite a few experiments with my IPAs with regard to pH including recently one mashed and sparged at 5.6 and in my experience there is a wide range of acceptable pH for this style. I have gone as low as 5.2 and it is a brighter snappier take to it. After trying 5.2 I decided it was as low as I wanted to go. Never had Heady Topper so can't comment on specifics, but I would bet my lunch is referring to mash temps.

To me, it's like all things, there's tradeoffs. Lower and the body thins out, hops are crisper and less course. Higher, the body is thicker and smoother, but hops are more pronounced but a tad courser. I'd say 5.4 is my sweet spot and a good balance of things.

A noticeable improvement to IPAs can be had with a boost of sulfate to 300ppm. I use gypsum to boost and with the additional Ca I also typically get a .2 unit reduction in postboil pH. So, that is 5.2 into the fermenter.

The only variable I have yet to change in my house IPA is the yeast, and with the encouragement of some other folks I will be trying WL007. My goal is to try and get the fruity hop flavors and aromas to "pop" or become more pronounced. Other brewers suggest this is attributed to esters of the yeast and not the hops...

 

[Yooper]

I will keep checking it over the next few brews. I am using split 50-50 DI water with ground water for a bicarbonate ppm of around 45. for this beer we targeted moshers pale ale water profile, with 1ml lactic acid addition. my mash is a bit different, we did a full volume no sparge mash, not sure if that would have an effect on final ph. I will also measure the ph of the final beer.

Did you use the same 50/50 split for the sparge water? If so, I'd suggest acidifying it (brunwater spreadsheet has a great tool for that!), or use 100% DI or RO water for the sparge. You don't want alkalinity in the sparge water if you can avoid it.

Since I have to refill my HLT for most beers anyway, I've been sparging with all RO water for most beers and I don't have to worry about sparge pH or tannin extraction.

EDIT- the "no sparge" part finally clicked with my little brain. NEVER MIND! (in my Gilda Radner voice).

 

[mtnagel]

Decided to sign up to respond to this thread.

I have made quite a few experiments with my IPAs with regard to pH including recently one mashed and sparged at 5.6 and in my experience there is a wide range of acceptable pH for this style. I have gone as low as 5.2 and it is a brighter snappier take to it. After trying 5.2 I decided it was as low as I wanted to go. Never had Heady Topper so can't comment on specifics, but I would bet my lunch is referring to mash temps.

To me, it's like all things, there's tradeoffs. Lower and the body thins out, hops are crisper and less course. Higher, the body is thicker and smoother, but hops are more pronounced but a tad courser. I'd say 5.4 is my sweet spot and a good balance of things.

A noticeable improvement to IPAs can be had with a boost of sulfate to 300ppm. I use gypsum to boost and with the additional Ca I also typically get a .2 unit reduction in postboil pH. So, that is 5.2 into the fermenter.

The only variable I have yet to change in my house IPA is the yeast, and with the encouragement of some other folks I will be trying WL007. My goal is to try and get the fruity hop flavors and aromas to "pop" or become more pronounced. Other brewers suggest this is attributed to esters of the yeast and not the hops...

Thanks for the info. Glad you signed up!

I was just putting together my water profile for an IPA and I wanted to get to 300 ppm sulfate, but my Ca is 132 ppm. Should I be concerned with that level? What Ca level are you at with 300 ppm sulfate?

 

[bob1852]

Thanks for the info. Glad you signed up!

I was just putting together my water profile for an IPA and I wanted to get to 300 ppm sulfate, but my Ca is 132 ppm. Should I be concerned with that level? What Ca level are you at with 300 ppm sulfate?

I've been extremely happy with this pale ale water profile from Bru'N water (which I think is also pretty similar to Randy Mosher's and Tasty McDole's).

Ca - 165
Mg - 18
Na - 25
SO4 - 300
Cl - 55
BiCarbonate - 180

 

[mtnagel]

Thanks! I think I'm going to go with the pale ale profile in Bru'n Water. I can get it almost exactly with my water and gypsum only.

 

[zwiller]

Thanks! I think I'm going to go with the pale ale profile in Bru'n Water. I can get it almost exactly with my water and gypsum only.

I can... Usually right around 2 grams per Gallon. :rockin: (please forgive me this is the first forum with this emoticon) Actually worried I might over use it...

Be sure to acidify sparge to knockdown alkalinity.

 

[mtnagel]

I always do (well the last few batches since I learned you are supposed to )

Mine is 1.67 g/gal gypsum to hit these numbers:

Calcium (ppm) 132.5
Magnesium (ppm) 9.0
Sodium (ppm) 26.0
Sulfate (ppm) 300.0
Chloride (ppm) 37.0
Bicarbonate (ppm) 47.1

 

[PlinyTheMiddleAged]

Brewed tasty mcdoles session pale ale.

Mash pH @15 = 5.45
Pre boil pH = 5.34
Post boil pH = 5.3

I kind of thought the post boil pH would have been lower, but this is the firs time I've measured it. Thoughts?

I would have thought that the pH would drop more from pre-boil to post-boil as well. Maybe since pH is a logarithmic scale and the boil is driving off a relatively small percentage of water and leaving the salts in place, the pH isn't changing much.

I just ran a quick experiment with Bru'n Water to confirm the above guess. I added gypsum and calcium chloride to the default grist to approximate the pale ale profile. I ended up with a mash pH of 5.3. If I doubled the salt additions (effectively boiling off half the water in an excel spreadsheet) I got a projected mash pH of 5.0.

So, if we boil off half our water, we should see a drop in pH of 0.3. Since we boil off much less than that, the pH drop will be much smaller.

An even easier way too look at this is to simply take the log base 10 of the wort volume post boil to pre boil. Again, if I boil 5 gallons down to 2.5 gallons, log10(2.5/5.0)=-0.3. I'd predict the same drop in pH as Bru'n Water says it should be. Using a more reasonable boil off rate, boiling 6.25 gallons down to 5.0 gallons would give me a pH drop of log10(5.0/6.25)=-0.097 - my meter would show a drop of 0.10 pH.

Still, your drop is even smaller - unless your boil off rate is really low or your pH measurements are slightly off.

 

[zwiller]

A thought: in a no sparge wouldn't the Ca be used up lowering mash pH so none would be available in the boil to drive pH down in the boil?

I should point out that I add the "sparge" salts in Bru'n water to kettle not sparge water.

 

[mchrispen]

If everything is equal - water mineralization and acidification, grist, boil off rate, other kettle additions - then I concur with your assessment Pliny.

It seems the correlation is more toward calcium concentration, which I don't fully understand the processes, in the kettle that drives hot and cold break - and buffers some of the so-called acidification we would expect - some of the calcium is tied up in the mashing process, the excess is passed into the kettle. I see far more pH drop when I have very hard water for an IPA than when I measure a saison. The delta in measurements are not linear... nor would I expect them to be so. And pH still has a function of temperature which can provide more issues unless adjusted to a reference.

Looking at my notes from the last few brewdays:

1. APA with the Pale Ale hardness profile - drops in the kettle from 5.50 to 5.25 me. Seen this at least 3 times in the last 6 months.
   
2. A saison mashed at 5.20 (120 pppm sulfate, 40 ca), dropped in the kettle to 5.12 into the fermenter.

Same batch size and boil off rates... roughly 1 gallon/hour on 10.5 batches.

Both demonstrated strong hot break despite the extreme difference in calcium concentrations. Both finished fermentation around 4.23... surprisingly close, yet tremendously different tastes and mouthfeel.

 

[mchrispen]

A thought: in a no sparge wouldn't the Ca be used up lowering mash pH so none would be available in the boil to drive pH down in the boil?

I don't believe that ALL of the calcium is used up... even Lime Slaking doesn't remove all of the calcium from hard water... it simply uses it to drive a reaction. I have added both to the mash and to the boil only - and don't see a great deal of difference, rather than managing mash pH.

 

[zwiller]

Touche' and I agree with your observations on pH drop and hardness and do not fully understand it either.

 

[mabrungard]

I would have thought that the pH would drop more from pre-boil to post-boil as well. Maybe since pH is a logarithmic scale and the boil is driving off a relatively small percentage of water and leaving the salts in place, the pH isn't changing much.

I just ran a quick experiment with Bru'n Water to confirm the above guess. I added gypsum and calcium chloride to the default grist to approximate the pale ale profile. I ended up with a mash pH of 5.3. If I doubled the salt additions (effectively boiling off half the water in an excel spreadsheet) I got a projected mash pH of 5.0.

So, if we boil off half our water, we should see a drop in pH of 0.3. Since we boil off much less than that, the pH drop will be much smaller.

I don't think this would be the case. The pH lowering effect of Ca and Mg are due to their reaction with malt phytins. The boiling concentration would not create more phytins for the reaction to extend. So although the spreadsheet says so, I don't think that the application can be extended in that way.

I'm hoping that AJ will comment on this!

 

[PlinyTheMiddleAged]

Well, that was my other thought - the pH reduction is due to a reaction and therefore boiling would have essentially no impact. However, not being a chemist, I had no idea if this was true or not. I therefore took the engineering approach and guessed!

So is the conclusion that once the mash is done and the malt reaction with the salts is complete that the pH will remain somewhat stable? In other words, is kettle pH pretty much the same as mash pH?

I'm glad you and AJ joined in the discussion - it's great having experts around.

 

[mchrispen]

I did some digging into Braukaiser's site and Brigg's "Brewing Science and Practice" which Kai references - there is very little information relative to specific hardness levels transitioning from the MLT to the BK... meaning the focus in the boil kettle is on specific proteins, and some residual phosphates in solution at a given pH level. I cannot find any pH measurements over 60 minutes or 90 minutes to determine any trends. Briggs seems to indicate that the calcium/phosphate reaction does continue into the BK releasing protons, but many of those protons are used to facilitate break formation (flocuation) attracting various protein molecules together. That pH does generally drop - seems to indicate that phosphates/calcium reactions are depleted or slowed to the extent that some additional free H+ remains present. The addition of kettle fining provides additional charged molecules that further facilitate flocuation. There was no indication of pH relationship to those finings. There is a comment that indicated that a lower pH will generally result in a clearer wort into the fermenter, but that the drop is usually no more than 0.1-0.2 pH units through the boil procedure (which is quoted by Kai on his pH page). Given the very narrow range of pH units here, it would be easy to dismiss my wider observation as measurement error.

I don't find any comments on Mg relative to this, but it's electrical charge is the same - it would seem that while sulfates and chlorides are concentrated, other ions (Ca) are/maybe bound up in precipitates both in the mash and boil kettles. Given the very low or absent Ca in many light lagers vs the fairly high levels expected in a pale ale, I would not expect the pH drift downward to be linear to the amount of Ca... based solely on observation and nothing else.

Where is AJ when you need him?

 

[ajdelange]

This last post explains is consistent with my understanding. If you have an acid (be it phosphoric acid, phytic acid or a protein) whose anion forms an insoluble complex with calcium and/or magnesium and some of that precipitates the equilibrium between the protonated anion and the anion is upset so that more of the protonated form gives up its proton to become the anion at the same time that the singly protonated form's equilibrium with the doubly protonated for is upset cause interconversion with release of more protons etc. Thus calcium phosphate (apatite), calcium phytate, and calcium protein 'salts' form during mash and boil and result in lowered pH.

This process continues until [Ca]^n[An]^m < Ksp where Ksp is the solubility product of the complex in question. Thus increasing Calcium ion does not add acid but does allow the process to continue until more An has been removed that would be removed if Ca were not supplemented. Removing water also increases the concentrations of both Ca and An.

On the other hand, boiling off water does not change the pH of a buffer by an appreciable amount because of the buffering action. Water leaves an the H+ concentration goes up which upsets the equilibrium between concentrations of the protonated and less protonated species. The extra protons are absorbed by the less protonated species restoring the equilibrium. For example, if we make a phosphate buffer with 0.1 mmol/L each of the mono and dibasic forms it has a theoretical pH of 7.1971. Boiling away half the water would shift to pH 7.1981.

 

[Calichusetts]

This last post explains is consistent with my understanding. If you have an acid (be it phosphoric acid, phytic acid or a protein) whose anion forms an insoluble complex with calcium and/or magnesium and some of that precipitates the equilibrium between the protonated anion and the anion is upset so that more of the protonated form gives up its proton to become the anion at the same time that the singly protonated form's equilibrium with the doubly protonated for is upset cause interconversion with release of more protons etc. Thus calcium phosphate (apatite), calcium phytate, and calcium protein 'salts' form during mash and boil and result in lowered pH.

This process continues until [Ca]^n[An]^m < Ksp where Ksp is the solubility product of the complex in question. Thus increasing Calcium ion does not add acid but does allow the process to continue until more An has been removed that would be removed if Ca were not supplemented. Removing water also increases the concentrations of both Ca and An.

On the other hand, boiling off water does not change the pH of a buffer by an appreciable amount because of the buffering action. Water leaves an the H+ concentration goes up which upsets the equilibrium between concentrations of the protonated and less protonated species. The extra protons are absorbed by the less protonated species restoring the equilibrium. For example, if we make a phosphate buffer with 0.1 mmol/L each of the mono and dibasic forms it has a theoretical pH of 7.1971. Boiling away half the water would shift to pH 7.1981.

I was JUST about to say that...

Rocking out my 5.19 IPA brew tonight...I'll check back in with results.