Yet more evidence that commercial brewers do not mash at 5.2 to 5.6 pH ...

[hopjuice_71]

They are asking for $50 to download it.

I was worried about that. The link takes me to a paywall as well. I just tried searching the whole title on Google Scholar (Factors Affecting Hop Bitter Acid Isomerization Kinetics in a Model Wort Boiling System) and it gave me a direct link to the pdf. Maybe try that?

One of the main advances, I feel, is that the authors carefully consider the relationship of a-acid solubility with temperature and pH, which hadn't really been done before (as far as I can tell). a-acids are fully soluble (within limits) at boiling or near boiling temperatures; however, when samples are cooled, their solubility decreases and they precipitate. Solubility is also pH dependent, meaning more material will precipitate if at a different pH. So, when samples are taken for measurement of a-acid and iso-a-acid and cooled to measurement temperature (room temp), some of the a-acid won't be measured as it has precipitated, and done so in a pH dependent manner as well. Because of this issue, which is a technical flaw in the assay, it makes it appear that hop utilization is pH dependent, when it likely isn't.

 

[Silver_Is_Money]

This linked study discusses multiple hop related issues involving isomerization and subsequent isomer-products degradation. To me it seems to indicate that if you want to degrade hop isomerization components, the quickest and easiest way to accomplish it is to add either CaCl2 or MgCl2, whereas CaSO4 had far less impact upon degradation, though the more mineralized the water, the greater the degradation effect. pH in going from 6 to 5 had a definite negative impact as well. If you really want to avoid negative effects and allow your hops to shine, boil at reduced temperature and don't use CaCl2 or MgCl2. (high altitude, or partial vacuum boiling anyone?)

By varying the wort composition and the boiling parameters, losses of isohumulones during wort boiling and wort treatment could be reduced. Boiling at atmospheric pressure for 90 min, comparable to a standard boil and hot wort treatment, led to losses of nearly 25% within 90 min. These losses could be minimized by lowering the temperature. High losses were also found when isohumulones were boiled at a low pH value, high original gravity and high water hardness. By optimizing these parameters, losses of isohumulones and thereby a decrease in less favourable bitter impressions can be attained.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2010.tb00783.x

Edit: This one threw me a curve ball I can't hit (as in comprehend):

Solubility of α-acids can be improved by using an increased pH value, which may result in an accelerated isomerisation reaction, although the isomerisation reaction itself is not affected by changes in pH.

If it says anything to me, it's saying that alpha acids are better solubilized at higher pH's, but once you get them to fully solublize in a low pH environment nothing else will be changed by the lower pH aside from the initial solubilization time. And isomerization must be preceded by solubilization. Can that be what it is saying? Again I must inject that pellet hops solubilize leagues faster than whole/leaf. Are pellets the answer to the negation of slower solubilization due to lower Wort pH?

 

[bierhaus15]

This thread has jumped around so much, not really sure what the debate is about now, but from both a large craft/macro brewery perspective targeting specific mash pH has more to do with maximizing malt efficiencies and optimizing exogenous enzyme activity (if used), than one pH number being better for beer flavor than another, within range. Also, per the boil acidification, the breweries that use this process are doing for so very different reasons than the small brewer/homebrewer, who may be looking for a quick solve for DH pH rise. Also, the prevalence of wort stripping, vacuum kettles, with calandria use, has made DMS removal a mostly non-issue and the loss of kettle isomerization is again, largely non-issue at working pH ranges. The bigger issues are wort stress for which mash pH is important, but more so wort chemical composition and final beer pH, principally for package stability.

 

[Silver_Is_Money]

Posts #251 and #260 have redefined (re-focused) the direction of this thread. @bierhaus15, the above is good information, but can target valuations be applied to it?

 

[brewbama]

@brewbama there's seems to be a typo somehow the two Pale Ale results are hardly similar.

If there was a typo it was at the point of information gathering. I cut and paste direct from my notes so typo is unlikely in posting here.

 

[bierhaus15]

Posts #251 and #260 have redefined (re-focused) the direction of this thread. @bierhaus15, the above is good information, but can target valuations be applied to it?

From a theoretical point of view, good question, but from the practical-relates to home brewing side of things; why would anyone be concerned with boil acidification regarding isomerization and color formation if you a). weren't brewing a bottled, 18 IBU, 3 SRM, tunnel pasteurized German Pils that needed a shelf life of 16 months, and b). were free to use whatever water/mash/kettle processing aids you wanted?

Lots of good info and discussion here, but IMO these target valuations are sorta apples to oranges, since much cited info here was to solve issues that largely apply to industrial brewers making products with extremely narrow quality parameters. Per specific targets, it depends on what are you trying to solve for, what is the process/limitations, and what ingredients are used. I can say from experience that general rules of thumb for pH targets work, but the specific deep dives into pH/process were to solve bigger issues than 'what makes the best tasting beer.'

 

[Silver_Is_Money]

I can say from experience that general rules of thumb for pH targets work, but the specific deep dives into pH/process were to solve bigger issues than 'what makes the best tasting beer.'

Would you be more inclined to come down on the side of RDWHAHB with regard to home brewing?

 

[bierhaus15]

Not at all. I just think there needs to be more context for what we are asking and trying to solve for... and that the data/solutions tailored for the largest breweries doesn't always apply to the home brewer, whom is looking at the result without knowing the original question. Sorry, carry on...

 

[hopjuice_71]

From a theoretical point of view, good question, but from the practical-relates to home brewing side of things; why would anyone be concerned with boil acidification regarding isomerization and color formation if you a). weren't brewing a bottled, 18 IBU, 3 SRM, tunnel pasteurized German Pils that needed a shelf life of 16 months, and b). were free to use whatever water/mash/kettle processing aids you wanted?

Lots of good info and discussion here, but IMO these target valuations are sorta apples to oranges, since much cited info here was to solve issues that largely apply to industrial brewers making products with extremely narrow quality parameters. Per specific targets, it depends on what are you trying to solve for, what is the process/limitations, and what ingredients are used. I can say from experience that general rules of thumb for pH targets work, but the specific deep dives into pH/process were to solve bigger issues than 'what makes the best tasting beer.'

Very nice post. A pragmatic recognition that the goals of commercial brewing are different from those of the homebrewer, and that the definition of "better" or "best" might be different in each case. I very much agree with this sentiment; its often forgotten. Regarding the discussion at hand, however, I believe there is mounting evidence, albeit anecdotal, that some homebrewers are noticing positive effects from kettle acidification. For my part, I brew a lot of hoppy beers and normalizing the kettle pH to the same value for each batch seems to have made the "hoppiness" of the beers noticeably more predictable and consistent, and thereby "better" by my standards (though I admit there may be some confirmation bias as I started acidifying in the kettle exactly to achieve this outcome...).

 

[Robert65]

I am still looking for primary sources on protein coagulation, but Briggs, et al. states, without citation, that "It is found that above pH 5.0 the amount of nitrogen precipitated... is fairly constant" but that less is precipitated at lower pH (which, it seems to me, will not be a condition we encounter.) So, provisionally, this would suggest that achieving an adequate hot break does not need to be taken into consideration when deciding the timing of the kettle acidification. All in all, it is looking to me more like the timing may be considered a matter of convenience.

 

[hopjuice_71]

Edit: This one threw me a curve ball I can't hit (as in comprehend):


If it says anything to me, it's saying that alpha acids are better solubilized at higher pH's, but once you get them to fully solublize in a low pH environment nothing else will be changed by the lower pH aside from the initial solubilization time. And isomerization must be preceded by solubilization. Can that be what it is saying? Again I must inject that pellet hops solubilize leagues faster than whole/leaf. Are pellets the answer to the negation of slower solubilization due to lower Wort pH?

It was not well articulated, but this is what it means. The isomerization reaction obeys first-order kinetics, which means that the higher the concentration of a-acids, the higher the velocity of the reaction to iso-a-acids. So, higher solubility at low pH means more a-acid, which means more production of iso-a-acids. That is the first part of the sentence. The last part of the sentence reflects that there is no inherent change to the kinetic constant governing the reaction at different pHs. Practically speaking, it seems like a bit of a strange sentence as I believe you would have to get to quite extreme hopping levels to reach solubility limits at boiling temperature, so pH really shouldn't feature much there (maybe possible in the days of the IBU race?).

 

[Robert65]

Was looking at a paper on what I thought was an unrelated topic, ascorbic acid oxidase in mashing, and spotted this little gem of a table showing pH over time in a mash with added ascorbic vs a control mash. Certainly looks like an example of mashes, regardless of the pH established at mashing in any whatever means, converging on a point in the 5.4 ballpark. Just another piece of the puzzle.

 

[Silver_Is_Money]

Due to the ascorbic acid addition I'm not sure this is going to be representative of the typical mash pH trend without ascorbic acid added. It may just show that over time the ascorbic acid is being consumed and transformed into a non acid salt, perhaps at least partially as it reacts with oxygen.

The control hits 5.5 at the 20 minute mash mark (about right where a home brewer will sample it), and then pretty much stays there. If they are precisely measuring pH to 3 decimal places, they must be using some premium equipment. A home brewer with a far less capable pH meter is more likely to read 5.5 at both 20 minutes and 60 minutes. Thus if it trended to a final pH, I'd call it 5.5.

 

[eric19312]

Not of the scientific article caliber @Silver_Is_Money was initially pointing at but came across this presentation which seems reflective of what pro brewers really do. Slides 18-19 confirm the target mash pH of 5.5-5.6 at 20C.
http://www.craftbrewersconference.com/wp-content/uploads/ImprovingBrewhouseEfficiency-Havig.pdf

 

[Silver_Is_Money]

It looks like their best efficiency was being achieved at 5.3 pH as measured at 65 degrees C. (or ~5.6 pH if measured at 20 degrees C.)

 

[hopjuice_71]

It looks like their best efficiency was being achieved at 5.3 pH as measured at 65 degrees C. (or ~5.6 pH if measured at 20 degrees C.)

Yes, a whopping 2% better efficiency when compare to "out of range" Not sure how much I buy into that number being very accurate.

 

[eric19312]

Yes, a whopping 2% better efficiency when compare to "out of range" Not sure how much I buy into that number being very accurate.

I dunno. They were aiming at helping their worst brewers who were at about 82% efficiency to perform more like their best performers who were at about 89-90% efficiency (total 7-8% difference). Seems like pH could account for about 25% of the overall gap while the remainder of the distance to the goal was due to crush.

The presentation provides insight into how pro brewers think and what they do about it. These brewers clearly do think 2% efficiency improvement matters and they do recommend testing pH to save that 2%.

Obviously 2% just doesn't matter on homebrew scale but the point of the thread is what pH do pro brewers mash at.

 

[Robert65]

...but the point of the thread is what pH do pro brewers mash at.

Hey, that should be in the title of the thread... [emoji38]

 

[Qhrumphf]

I dunno. They were aiming at helping their worst brewers who were at about 82% efficiency to perform more like their best performers who were at about 89-90% efficiency (total 7-8% difference). Seems like pH could account for about 25% of the overall gap while the remainder of the distance to the goal was due to crush.

The presentation provides insight into how pro brewers think and what they do about it. These brewers clearly do think 2% efficiency improvement matters and they do recommend testing pH to save that 2%.

Obviously 2% just doesn't matter on homebrew scale but the point of the thread is what pH do pro brewers mash at.

Whoa.....It's almost like some times pros do things because it makes better beer...

...And other times they do things because it makes cheaper beer.

 

[eric19312]

Whoa.....It's almost like some times pros do things because it makes better beer...

...And other times they do things because it makes cheaper beer.

pros ... it's a business right? thats what pro means...

 

[Qhrumphf]

pros ... it's a business right? thats what pro means...

Guess depends on whether you're asking the brewer or the accountant lmao

In seriousness I sense most folks in this thread (as in I haven't seen anything to suggest otherwise) are well aware of the distinction between maximizing quality and minimizing cost, but it's important to not lose the forest through the trees.

 

[TheHopfather]

So what are you guys doing in order to calculate the acid addition in the boil? I like the ideas in this thread and would like to give it a shot, just curious if there is an easy way to calculate the acid addition after the mash is complete. Are you just adding acid, checking pH and adjusting until you hit 5.1 ~ 5.2 pH in the boil?

 

[Silver_Is_Money]

So what are you guys doing in order to calculate the acid addition in the boil? I like the ideas in this thread and would like to give it a shot, just curious if there is an easy way to calculate the acid addition after the mash is complete. Are you just adding acid, checking pH and adjusting until you hit 5.1 ~ 5.2 pH in the boil?

There are assuredly other methods, but I've incorporated "Kettle pH Made Easy" within "Mash Made Easy". The kettle pH adjustment is thereby done for you within this sheet found within 'MME', and the process is simple, easy, and (hopefully) quite intuitive to understand. Plus it's free.

 

[Robert65]

The calculator mentioned is more sophisticated, and is very easy to use out of the box, but I have long used a quick and dirty, back of the envelope, method, empirically dialed in, that works for me. Others could do the same sort of empirical development if they wish.

I started with some values for the buffering capacity of wort as determined by Kolbach, based on the original weight of grist (the residual buffering of which is what needs to be overcome,)* which are cited variously but run around 32 mEq/(pH • kg). Observing results over numerous batches, I determined that my worts can be assumed to be well represented by an approximation of 30 mEq/(pH • kg). Using lactic acid 88%, I round off its normality, at pH 5.4, to 11 mEq/ mL. The natural drop in pH during the boil varies, but my longtime observation is that it is typically about 0.1 units, in practice, under conditions in my brewery (this is also consistent with Kunze's statements.) So this leads me to a simple formula: (desired delta pH - 0.1) * grist in kg * 30 / 11 = mL lactic acid 88% required. This gets me as close as anything else, but YMMV, as it is, as I said, based in part on empirical refinement of my original assumptions derived from the available literature.

*I use actual grist weight. Kettle pH Made Easy ingeniously generates an "effective grist weight" based on volume and gravity. The relative virtues of these approaches has, I believe, been discussed elsewhere on these boards.

 

[TheHopfather]

@Silver_Is_Money ah, okay so its inside Mash Made Easy. It sounded like you were beta testing a separate version elsewhere. I typically use BruNWater so I'm not super familiar with yours, I'll give it a shot.

@Robert65 just so I've got this right, your formula would like look something like this (assuming 5.65 pH in the mash and a 5.8 kg grist);

((5.65 - 5.10) - 0.1) * 5.8kg * 30/11 = 7.12 mL?

Edit: I'm still a bit confused as the kettle pH adjustment. Are we shooting for 5.0 ~ 5.1 at room temp, or adjusting similar to mash temp so we'd be reading 5.40-ish at room temp? You'd think after 295 posts I'd have figured that part out.

Edit 2: I opened up MME, it says 5.0 ~ 5.2 pH for the COOLED beer. Makes sense now. Edited my formula example.

 

[Robert65]

@TheHopfather, yes that's how I calculate it. Again, I've incrementally tweaked the values for buffering and pH drop in the boil until the formula matched actual results I was getting to within +/- 0.05 units. But it works as well for me as a more sophisticated approach like the one in MME, probably because there are still things we don't understand, and I dont know how specific to my process and its idiosyncrasies my formula's success might be. MME does offer the convenience of multiple choices for acid, and selections for sg/Plato and metric or US units. What I find convenient about my approach is that I don't have to have an accurate preboil volume measurement, which I usually don't have. While my formula and MME may generate slightly different recommendations for quantity of acid, any resulting kettle pH difference is negligible; again, there's probably much about wort buffering we still don't fully understand. (Full disclosure, I was one of the beta testers on the tool in MME.)

 

[mabrungard]

The buffering of kettle wort is the same as mash wort. You can calculate the amount needed by checking how much acid is needed to drop your mash pH to the level you want as if were in the mash tun. Of course, this assumes that the sparging water has been properly neutralized to near zero alkalinity.

 

[TheMadKing]

The buffering of kettle wort is the same as mash wort. You can calculate the amount needed by checking how much acid is needed to drop your mash pH to the level you want as if were in the mash tun. Of course, this assumes that the sparging water has been properly neutralized to near zero alkalinity.

Thanks for confirming Martin, that's the assumption I was working off of for using Bru'n water for kettle pH adjustment.. Glad to know it wasn't a terrible idea

 

[hopjuice_71]

I dunno. They were aiming at helping their worst brewers who were at about 82% efficiency to perform more like their best performers who were at about 89-90% efficiency (total 7-8% difference). Seems like pH could account for about 25% of the overall gap while the remainder of the distance to the goal was due to crush.

The presentation provides insight into how pro brewers think and what they do about it. These brewers clearly do think 2% efficiency improvement matters and they do recommend testing pH to save that 2%.

Obviously 2% just doesn't matter on homebrew scale but the point of the thread is what pH do pro brewers mash at.

Sure, but where did that number come from? An average? How do we know it wasn't 2% but with +/- 4% error?

...yes I am a nerdy scientist.

 

[eric19312]

Sure, but where did that number come from? An average? How do we know it wasn't 2% but with +/- 4% error?

...yes I am a nerdy scientist.

OK again...how many professional brewers are hard core scientists? Primary qualification for getting into the field seems to be ability to lift a 50 lb sack of grain and a love of cleaning stainless steel.