Mash pH

[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.

 

[ajdelange]

It occured to me this morning that a simpler explanation for the buffer is that a buffer is a mixture of an acid and a base and if water is removed both are concentrated by the same amount so that their concentration ratio stays the same.

 

[mchrispen]

I brewed a Belgian Pale Ale this weekend. Here are the results:

Using RO water with 6.8 grams of calcium chloride and 4.7 grams gypsum for a 10.5 gallon batch (Amber Malty target in Bru'n) and simple grain bill:

1. Mash pH settled at 5.35, and dropped slightly into the boil kettle to 5.32. I acidified the sparge to 6.0 to be safe.
2. Boil pH dropped to 5.14 into the fermenter, with hot break formation about 10 minutes into the boil. Boil was very strong - I usually boil off about 1.2-1.3 gallons/hour.

That is a 0.18 drop in pH units in the boil kettle - on the fringe of the 0.1-0.2 range expected. This was a malt forward batch with relatively little hardness, and calcium at about 58 ppm. I had planned to check on 5 minute intervals, but was interrupted and mixed the samples so abandoned that. Will try this on a future IPA or APA brew.

I am wondering if larger swings are potential using RO water rather than treated tap water where most or all of the alkalinity has been removed. Could this leave more calcium (depending on water target profile) to react with phosphates, etc. from the mash and into the boil, skewing the expected pH to drop lower?

 

[zwiller]

I would say no. Acid treatment of tap water should leave Ca levels unchanged so I think the kettle drop should be similar to RO. Lime treatment would precipitate Ca, so that's another ball of wax...

Boy am I a pH geek since I really the values you used for that brew but I have no idea of the ingredients...

 

[PlinyTheMiddleAged]

Well, last night I brewed two 1 gallon batches of beer - both used identical water recipes (distilled with added salts). I was targeting 5.4 and 5.2 for each of the mashes. I used acidulated malt to drop the pH (replaced some 2 Row with acidulated malt). I scaled down the Zombie Dust recipe found on the recipe database here (and adjusted slightly to reasonable weights).

Both worts were identical in terms of pre-boil sg and post-boil og. However, I did miss my targeted pH values slightly - 5.45 and 5.29. I'll report back when the batches are fermented and bottled.

I will say that I hope to have my hop forward beers figured out soon. Brewing one gallon diagnostic batches of beer is a heck of a lot of work for such a yield. I look forward to brewing decent IPAs and going back to 5 gallon batches.

 

[mtnagel]

Cheers and kudos for doing the experimental batches

That said, my gut says you aren't going to taste a difference in those unfortunately. But I guess that's good to know too. Still looking forward to the results though.

 

[PlinyTheMiddleAged]

I'm afraid you are correct - I don't think I'll see too much difference between these two brews either. I was hoping for a slightly larger spread and slightly lower pH (was looking for 5.4 and 5.2 and got 5.45 and 5.29).

If I had a slightly greater spread, I might be able to see some difference in flavor. Also, wanted to get a touch lower in pH obviously.

The other tough thing about one gallon brews is the precision needed. It is tough measuring salts out to the hundredth of a gram.

 

[Calichusetts]

Results are in:

mash pH 5.19

Tasting:

Brighter and cleaner in terms of hop profile. I've always wondered how lawsons got such a "bright" hop presence in their beer, maybe pH has something to do with it. FG was 1.014 but I found the dryness to be accentuated, possibly by the pH

Overall, nothing earth shattering. A little more crisp, might have an affect on taste and aroma, possibly making it cleaner or crisper. Certainly, nothing negative.

 

[mtnagel]

Thanks for the update.

 

[PlinyTheMiddleAged]

Calichusetts,

Thanks for the input! So, does your taste preference lie with a 5.2 mash pH for hoppy beers? Or will you stick with the standard 5.4 pH in the future?

My small batches of Zombie Dust are still in the fermenters - I may bottle them this coming weekend. Then it'll be three weeks of bottle conditioning. However, as previously noted, my targeted pH values weren't where I wanted them to be. As a result, it is likely that I won't perceive much difference in the taste. I'll report back regardless.

Thanks again for your input!

 

[PlinyTheMiddleAged]

All,

Just had another thought on this topic (kind of an obvious one) - has anyone emailed/asked Kimmich what he meant about his statement concerning mash pH? Was he talking about pH at mash temperatures or pH at room temperature? See - I said it was obvious.

 

[Calichusetts]

Calichusetts,

Thanks for the input! So, does your taste preference lie with a 5.2 mash pH for hoppy beers? Or will you stick with the standard 5.4 pH in the future?

My small batches of Zombie Dust are still in the fermenters - I may bottle them this coming weekend. Then it'll be three weeks of bottle conditioning. However, as previously noted, my targeted pH values weren't where I wanted them to be. As a result, it is likely that I won't perceive much difference in the taste. I'll report back regardless.

Thanks again for your input!

I think I missed the boat on the whole "5.4 as standard." When I actually got into mash pH I simply put in my favorite recipies into a water profile calculator. I found most were in the 5.3s, one around 5.4 and several in the high 5.2s

I think I learned that it can accentuate certain aspects of a beer and you can certainly use that to drive your recipe formula to make an outstanding beer. I'm trying another 5.2 this weekend with a different recipe to see if its consistent.

 

[PlinyTheMiddleAged]

All,

Just had another thought on this topic (kind of an obvious one) - has anyone emailed/asked Kimmich what he meant about his statement concerning mash pH? Was he talking about pH at mash temperatures or pH at room temperature? See - I said it was obvious.

Well, I sent off an email to the brewery asking for clarification on his statement. I'll let you all know if I get a response.

 

[PlinyTheMiddleAged]

I think I missed the boat on the whole "5.4 as standard." When I actually got into mash pH I simply put in my favorite recipies into a water profile calculator. I found most were in the 5.3s, one around 5.4 and several in the high 5.2s

As to the "5.4 standard", I was going by the Instructions tab on the Bru'n Water workbook. Martin references "Malting and Brew Science" as the source for setting an optimum mash pH of 5.3 to 5.5. The reference can also be found on the Mash Acidification tab.

 

[Calichusetts]

As to the "5.4 standard", I was going by the Instructions tab on the Bru'n Water workbook. Martin references "Malting and Brew Science" as the source for setting an optimum mash pH of 5.3 to 5.5. The reference can also be found on the Mash Acidification tab.

I'm sure its apart of better brewing. I was just saying that I never knew about pH for a while when I started. I just didn't pick up on it early in my brewing. By the time I did, I simply started calculating my best recipes and found they were in that range.

I'm still curious as to the effects when you get lower than 5.1

 

[PlinyTheMiddleAged]

Well, I wrote John an email a few hours ago and this is what I got back:

"Jeff, those are a target for hot side.

John Kimmich

The Alchemist
35 Crossroad
Waterbury , VT
05676"

That sure is a fast response (and a heck of a lot easier than brewing multiple small batch brews).

So, it looks like The Alchemist is looking for 5.4 to 5.6 pH at room temp. Makes me feel like I have at least that part of the brewing process figured out. I'll continue to shoot for 5.4 in my IPAs for now.

Still curious about how others' experimental brews may turn out.

 

[PJM]

A lot of you guys mention acidifying your sparge water. Is that only necessary if you fly sparge or should you also do it if you batch sparge?

 

[zwiller]

I debunked that some time ago. The decision to acidify sparge depends on the alkalinity of your water not your sparge technique. Acidification of sparge is less about extracting tannins and more about setting up proper KO pH IMO.

 

[mchrispen]

Acidifying the sparge water does two things, with the same primary purpose: it reduces the residual alkalinity of the sparge water and it prevents the mash pH from rising during sparge - over an arbitrary level, such as 5.8 or 6.0. By limiting the maximum pH of liquor going into what should already be roughly 5.4 (or so), then the mash pH cannot rise beyond the highest number (5.8) - which eliminates most concerns over tannin extraction. This should apply to both batch sparging and fly sparging, and assumes reasonable temperatures during sparge.

If you are using RO or DI water for your sparge, you will not need to acidify your sparge water in most cases.

 

[mchrispen]

Colby makes an argument against acidifying sparge water in most cases.

http://beerandwinejournal.com/acidify-sparge-water/

Something to consider. I tend to acidify my sparge water to 5.8, mostly because I can as well as insurance against tannin extraction. The tiny amount of acid I need is well below the flavor threshold.

 

[mabrungard]

Matt,

Chris' observations may be fine for his brewing practice, but they could be inapplicable to other brewers. Having judged beers from across the country and more importantly, from the alkaline regions of the Midwest and Florida, I think that Chris' argument that beer astringency is rare, is short-sighted. I've had plenty of astringent, puckering beers. The advice to NOT acidify sparging water is more likely to be wrong for most brewers in the US.

Take a look at that map of alkalinity in the US (yellow map) that is shown on the Water Knowledge page of the Bru'n Water site. There are huge swaths of the country that show up with high alkalinity surface waters and that is likely to correspond to high alkalinity tap waters.

For those of us with great brewing water (low mineralization), acidification is certainly optional and unnecessary. For the rest of brewers, acidification of their brewing water is one of the simplest and surest ways to improve their brewing results. (PS: I only have 'great' brewing water because I have a RO unit).