Statistical significance of mash pH estimates?

[Silver_Is_Money]

I just realized I could use your program. When I entered everything including 3.1ml of lactic acid, it changes the pH to 5.40 which was my target number.

I am confused as well. If the pH meter is calibrated minutes before at taking actual samples, one would think the meter would be accurate. What could I being doing wrong?

Software is making a multitude of internal 'math model' guesses based upon perceived slopes and perceived nominal averages (generally with poor to midland 'R' correlation factors) for the various grist components. Your meter is making real readings of real malts. Do not fall into the classic trap of believing software over an actual pH reading of a real recipe.

 

[Silver_Is_Money]

Estimated pH right at 5.56! Of course I could change parameter for any component and get a different answer but I guess this proves that even one pellet from a shotgun load has a chance of going through the bullseye. You can see from the right to columns where the protons went (target pH 5.4) and how they pulled the pH estimate.

A.J., what does your gen 2 software predict for the pre-adjustment mash pH if you assume 5.81 as pHDI for the Pilsner malt? Briess and Weyermann seem to be more in agreement with 5.81 than with 5.62. They may even suggest a bit higher, at 5.83-5.84 pHDI. And lastly, how many mL's of 88% lactic acid are required to bring it to 5.4 pH for the case of 5.81 pHDI Pilsner?

Mash Made Easy says 5.59 as the pre-lactic acid mash pH when the Pilsner is 5.81 pHDI (as can be seen above).

 

[bracconiere]

before this cus'o'rama gets locked...i'd want to add if you don't have a ph meter, don't adjust ph....i tried and it was acidic the yeast wouldn't even ferment it...

and yes .2 +/- ph makes a huge difference on efficiency, this is a logarithmic scale....

just wanted to add my two cents, no meter, let it be...meter by all means dial it in to the nearest 1/10th....

(damn, i only made it to the bottom of page one, sorry if this was said, didn't realize there were 3 full pages in this thread)

 

[Silver_Is_Money]

Estimated pH right at 5.56! Of course I could change parameter for any component and get a different answer but I guess this proves that even one pellet from a shotgun load has a chance of going through the bullseye. You can see from the right to columns where the protons went (target pH 5.4) and how they pulled the pH estimate.

A.J., just to clarify, was your prediction of 5.56 mash pH before or after any 88% lactic acid was added?

 

[dmtaylor]

<-- Measures mash pH at mash temperature and adds 0.25 to get room temperature pH.
<-- Adds either "a glug" of vinegar, or 1/8 teaspoon baking soda, to adjust pH if he feels like it... or doesn't even measure pH or adjust at all if he doesn't get around to it.
<-- Doesn't add other salts anymore except maybe gypsum to IPAs.
<-- Still manages to make pretty good beer most of the time, and excellent beer some of the time.

 

[bracconiere]

<-- Measures mash pH at mash temperature and adds 0.25 to get room temperature pH.
<-- Adds either "a glug" of vinegar, or 1/8 teaspoon baking soda, to adjust pH if he feels like it... or doesn't even measure pH or adjust at all if he doesn't get around to it.
<-- Doesn't add other salts anymore except maybe gypsum to IPAs.
<-- Still manages to make pretty good beer most of the time, and excellent beer some of the time.

spot on! i'd just say phosphorous would be a better choice than acetic though.....ph is getting nitpicky like a pro worried about getting 90% efficiency instead of 75%, because it matters when your brewing budweiser trucks full, not buckets.....

 

[dmtaylor]

If I had phosphoric laying around, I'd use it. I have tons of vinegar laying around. A couple of old cider batches went off years ago. It's not going to waste.

 

[bracconiere]

lol, i'd defiantly use a meter then, rotten cider would probably **** up the flavor....damn, another thread i'm ******* up but i'll say it anyway...if my cider was going off i would have made apple jack first sign....lol

and i've got a bottle of phosphoric just for it, but most of my batches 'according to a meter' need bicarb not acid....

 

[ajdelange]

A.J., what does your gen 2 software predict for the pre-adjustment mash pH if you assume 5.81 as pHDI for the Pilsner malt? Briess and Weyermann seem to be more in agreement with 5.81 than with 5.62. They may even suggest a bit higher, at 5.83-5.84 pHDI.

First lets look at the water deficit. I had the thing set for a Kolbach factor of 3.5 which assumes that the entire Kolbach reaction occurs in the mash tun. That's very unlikely - 7 is probably a more realistic number but let's leave it at 3.5 so this exercise doesn't become more apples and oranges than it already is.

With the base malt at 72% of the grist and other malts having pHDI's in the vicinity it should not be surprising that the base malt pretty much sets the estimated mash pH. Thus when I use a Pilsner Malt, also by Wyermann and also one that I measured, that has a pHDI of 5.85 I get an estimated mash pH of 5.81. When I use a Rahr Pils malt measured by Joe Walts with a DI pH of 5.80 I get an estimated mash pH of 5.78 and when I use Wyermanns regular pils which I measured at 5.62 I get an estimated mash pH of 5.65

Mash Made Easy says 5.59 as the pre-lactic acid mash pH when the Pilsner is 5.81 pHDI (as can be seen above).

If I dummy up a Pils malt with pHDI of 5.81 I get a predicted mash pH of from 5.78 - 5.79 over a range of buffering (assumed linear) of -30 to -50. Given the dominance of the base malt 5.59 seems quite low.

And lastly, how many mL's of 88% lactic acid are required to bring it to 5.4 pH for the case of 5.81 pHDI Pilsner?[/QUOTE] 15.7 mL.

A.J., just to clarify, was your prediction of 5.56 mash pH before or after any 88% lactic acid was added?

Yes, 35.5 mEq worth corresponding to the 3.1 mL of 88% lactic cited in the quote. Clearly not enough as the bottom line shows that another 66 mEq are needed. That's about 10 mL total. You've got all malts with positive deficits with respect to pH 5.4 and nothing to offset that except a little calcium. And if you use a malt with even more alkalinity (the 5.81) you'd need even more acid.

It all computes. Or seems to.

 

[ajdelange]

and yes .2 +/- ph makes a huge difference on efficiency, this is a logarithmic scale....

No. It doesn't. One of the reasons pH is on a logarithmic scale is that things in nature respond logarithmically. 0.2 pH will make very little difference in efficiency but it can make quite a difference in flavor and that's why brewers track it.

spot on! i'd just say phosphorous would be a better choice than acetic though.....ph is getting nitpicky like a pro worried about getting 90% efficiency instead of 75%, because it matters when your brewing budweiser trucks full, not buckets.....

A pro is not solely concerned about efficiency. He also worries about the quality of his product. He knows that a better tasting beer will sell better and thus offset the cost of a little more malt. But as noted above an 0.2 difference in pH isn't going to make much of a difference in conversion efficiency. To see this look at congress mash data as specified on the maltsters data sheets. Various malts mash at various pH's and all yield about the same extract plus or minus a percent or so.

and i've got a bottle of phosphoric just for it, but most of my batches 'according to a meter' need bicarb not acid....

Unless you are making mostly stouts and porters you are not using your meter correctly.

 

[dmtaylor]

lol, i'd defiantly use a meter then, rotten cider would probably fudge up the flavor....damn, another thread i'm ****ing up but i'll say it anyway...if my cider was going off i would have made apple jack first sign....lol

Oh, I dunno... chicks dig apple cider vinegar. It's not really bad; it's just vinegar. I could put it on salads. I also have used it as conditioner in my hair, works well with baking soda.

 

[bracconiere]

First lets look at the water deficit. I had the thing set for a Kolbach factor of 3.5 which assumes that the entire Kolbach reaction occurs in the mash tun. That's very unlikely - 7 is probably a more realistic number but let's leave it at 3.5 so this exercise doesn't become more apples and oranges than it already is.

With the base malt at 72% of the grist and other malts having pHDI's in the vicinity it should not be surprising that the base malt pretty much sets the estimated mash pH. Thus when I use a Pilsner Malt, also by Wyermann and also one that I measured, that has a pHDI of 5.85 I get an estimated mash pH of 5.81. When I use a Rahr Pils malt measured by Joe Walts with a DI pH of 5.80 I get an estimated mash pH of 5.78 and when I use Wyermanns regular pils which I measured at 5.62 I get an estimated mash pH of 5.65

If I dummy up a Pils malt with pHDI of 5.81 I get a predicted mash pH of from 5.78 - 5.79 over a range of buffering (assumed linear) of -30 to -50. Given the dominance of the base malt 5.59 seems quite low.

And lastly, how many mL's of 88% lactic acid are required to bring it to 5.4 pH for the case of 5.81 pHDI Pilsner?

15.7 mL.

Yes, 35.5 mEq worth corresponding to the 3.1 mL of 88% lactic cited in the quote. Clearly no enough as the bottom line shows that another 66 mEq are needed. That's about 10 mL. You've got all malts with positive deficits with respect to pH 5.4 and nothing to offset that except a little calcium. And if you use a malt with even more alkalinity (the 5.81) you'd need even more acid.

It all computes. Or seems to.[/QUOTE]


i just wanted to say...i've been drinking and say 'say what' ! Kolbach? wyermann?...lol, aren't we all just trying to make a drinkable beer....Maybe they need to add a 'Pro Brewer' discussion topic for this sorta thing....

i liked @dmtaylor 's post, what are you trying to do get rich? lol

and i'm sorry for myself if i sound stupid.....or lost the point of this thread somewhere....

 

[dmtaylor]

i just wanted to say...i've been drinking and say 'say what' ! Kolbach? wyermann?...lol, aren't we all just trying to make a drinkable beer....Maybe they need to add a 'Pro Brewer' discussion topic for this sorta thing....

i liked @dmtaylor 's post, what are you trying to do get rich? lol

and i'm sorry for myself if i sound stupid.....or lost the point of this thread somewhere....

We are in the "Brew Science" forum. A select few own the place. I am not one of them.

I always figure, if we can't have a little levity around here, then why do we bother to exist?

Cheers mate.

 

[ajdelange]

Well we all get a little confused when tipsy. You are actually in the Brewing Science forum where we discuss brewing science. You have apparently erroneously landed here.

 

[dmtaylor]

Well we all get a little confused when tipsy. You are actually in the Brewing Science forum where we discuss brewing science. You have apparently erroneously landed here.

I try, and often succeed, in keeping things entertaining even when not tipsy.

Cheers.

 

[bracconiere]

how sweet, i'm getting into my first fight on this forum! maybe we'll make up! lol

i can tell you without my meter a .2 ph difference makes about a 5% difference to effeminacy for 'my homebrew'....

and i don't know how half my message is still here when i went back to read yours?....huh... besides all the bickering, at me, i see it is the sciences forum, sorry... and, ... well i don't know i just clicked a link in the recents posts and thought i'd share with someone asking about water calcs and ph...i've never had luck with them...and a meter is all that works for me, i can tell you with my water even store bought malt is acidic, with my water and i have to add pot bicarb to get it up to 5.3 or so...

 

[bracconiere]

...

 

[ScrewyBrewer]

Here are the Gen1 predictions I get from ezRecipe when inputing @CodeSection's grain and water additions. Short of brewing this recipe myself. And taking a mash pH sample at 30 minutes I'm still trying to see where the 0.15 pH difference is. I use anhydrous calcium chloride in my formula because the LD Carlson stuff I use never seems to absorb water or appear gooey.

Just the grains....

...with gypsum and calcium chloride...

...with lactic acid addition.

ion balance...

...acid contribution.

 

[ScrewyBrewer]

As an aside, I find it interesting that both BS3 and ezReipe (ScrewyBrewer's latest spreadsheet) use D.M. Riffe's formulas, yet one (ezRecipe) arrives at ~3.1 mL of lactic acid, while the other (BS3) arrives at ~7 mL's.

My guess it has to do with how Riffe's formulas are implemented and which formulas.

 

[Silver_Is_Money]

A.J., I just double checked the DI_pH data that Briess sent to me and it lists their Pilsner malt (the older one, not their brand new 'Synergy Select Pilsner') at 5.83. And a glance at analyticals for individual pallet lots of Weyermann malts as found on the Cryermalt website shows that a multitude of individual lots of their Pilsner, Bohemian Pilsner, and Floor Malted Pilsner are all coming in at between 5.83 and 5.84 pH (with Weyermann admittedly referring to this measurement specifically as "wort pH", and not directly as "DI_pH", or as "Mash pH", or as "Congress Mash pH").

It seems that your measured 5.62 pHDI for Weyermann Pilsner may represent an outlier lot.

Call me a bit skeptical, but the idea of adding 15.7 mL of 88% lactic acid to the mash water of a batch utilizing a Pilsner malt of pHDI 5.81 (as opposed to 5.62) seems a bit out of line to the high side.

 

[ajdelange]

i can tell you without my meter a .2 ph difference makes about a 5% difference to effeminacy for 'my homebrew'....

I think that theory about beer and testosterone has been debunked (how's that for levity?). But I have to ask how you know there is an 0.2 pH difference without your meter.

.and a meter is all that works for me,

I think everyone here is well aware that calculators should be used only for guidance and as learning tools and that the proof of the pudding is in a pH meter reading but you have to know how to use a meter.

i can tell you with my water even store bought malt is acidic, with my water and i have to add pot bicarb to get it up to 5.3 or so...

And I can tell you that if you tell me that you are not using your meter properly possibly because it is defective.

 

[ajdelange]

A.J., I just double checked the DI_pH data that Briess sent to me and it lists their Pilsner malt (the older one, not their brand new 'Synergy Select Pilsner') at 5.83. And a glance at analyticals for individual pallet lots of Weyermann malts as found on the Cryermalt website shows that a multitude of individual lots of their Pilsner, Bohemian Pilsner, and Floor Malted Pilsner are all coming in at between 5.83 and 5.84 pH (with Weyermann admittedly referring to this measurement specifically as "wort pH", and not directly as "DI_pH", or as "Mash pH", or as "Congress Mash pH").

It seems that your measured 5.62 pHDI for Weyermann Pilsner may represent an outlier lot.

Perhaps. I have measured Weyermann malts with pHDI in this upper region but I have measured others that aren't. This one is the one I use the most. Not in a position to grab another bag and check again. I can, of course, use any malt parameters you would like me too to answer specific questions. But I can't assert that what I measured for pneumatic pils represents what a brewer is actually using better than what I measured for floor pils or what a website says or what Joe Walts measured.

Call me a bit skeptical, but the idea of adding 15.7 mL of 88% lactic acid to the mash water of a batch utilizing a Pilsner malt of pHDI 5.81 (as opposed to 5.62) seems a bit out of line to the high side.

I can get that down to about 12.7 if you like. The 15 mL number included nonlinearity terms typical of these malts and was for the upper range of alkalinity with respect to the linear term (-50). Setting that to -40 and taking out the non linear terms we get 12.7. Let's do the numbers. Target_pH - pHDi = 5.4 - 5.81 = -0.41. Buffering of -40, typical for these malts implies 16.4 mEq/kg. 88% lactic acid to pH 5.4 is 11.45 N so 16.4/11.45 = 1.43 mL per kg. We've got 6.68 kg of this malt so that's 6.68*16.4/11.45 = 9.57 mL for this malt alone. Then we have three other malts with deficits of 68 offset only by 33 mEq for the calcium in the water so that's another 35 mEq requiring another 3.06 mL for a total of 12.57. The message should be that it is very important to know as much as possible about the malts titration curve. DI pH alone isn't enough. DI pH plus first term buffering is getting closer but for a good estimate of acid required obviously you have to know how much acid it takes for each grain to hit a particular pH and that depends on the higher order buffering terms too - the more so the farther pHDI is from the target pH. What is interesting and note worthy is that pH prediction without acid addition is not nearly so sensitive as the predicted pH will be, in a grist where one malt dominates, close to the pHDI of that dominant malt.

 

[ajdelange]

I'm still trying to see where the 0.15 pH difference is.

That's where the voltmeter can help you. Look within your software to see how much each component pulls the pH. Compare those to the ∆pH numbers in the proton deficit summary. If you don't see agreement for a particular component pursue that component.

 

[Silver_Is_Money]

The "Cryermalt" website seems to merely take snapshots of Weyermann analytical sheets and post them. you can search by specific lots. or just browse through all of them (66 pages of them). I waded through a few pages and the Pilsners were all pHDI 5.83 or 5.84. Admittedly I did not review all 66 pages worth of data, each of which contains the analyticals for 10 lots of malt.

http://www.cryermalt.co.nz/malt-lot-analysis-weyermann/

 

[ScrewyBrewer]

That's where the voltmeter can help you. Look within your software to see how much each component pulls the pH. Compare those to the ∆pH numbers in the proton deficit summary. If you don't see agreement for a particular component pursue that component.

I do have 3 days to myself this weekend to get familiar with the voltmeter.

 

[CodeSection]

@ajdelange and @Silver_Is_Money , I'm going to mash the Briess Rye Malt tonight and I need clarification on two items:

1) AJ asks to mash at 50c which is 122F and SIM asks 146-158F. Can we agree on a temperature?

2) AJ asks to use 40g of malt and SIM asks to use 50g. Can we agree on how much?

First round: XXg of Briess Rye Malt with 100 ml of distilled water mashed between XXX-XXX degrees with frequent stirring for 60 minutes. Take samples at 30 minutes and 60 minutes and cool to room temperature (~72F) ASAP. Take pH reading.

Second round: Repeat the above, however, add 200mg sodium bicarbonate to 100 ml of distilled water.

 

[ajdelange]

I'll state my reason for suggesting 40 grams, 100 mL and 50 °C. Those are the conditions under which I have measured all the malts I have done titrations on. Those are the values in the MBAA paper and, AFAIK, those are the values Joe Walts used in his measurements. So they are a sort of de facto standard. I chose 50 °C as I thought it a typical strike temperature as it is at the lower edge of the protein rest temperature range and is not very hard to maintain over the test period nor is it too hard on pH electrodes. I chose 40 grams and 100 mL as they are representative of a typical 2 L/kg mash thickness and give a test mash thin enough to readily work with thus facilitating withdrawl of a dub sample for the 30 minute measurement.

 

[Silver_Is_Money]

My belief is that what we are attempting to replicate is actual mash conditions via which to derive DI mash pH.

You might want to do two sample procedures and measurements, one using A.J.'s criteria, and one using mine, to determine if there is a difference.

 

[ScrewyBrewer]

I'm going to mix 80g of malt with 200ml of 122F RO water in a flask. And then spin the test mash on a stir plate for an hour. Taking a sample at 30 minutes and 60 minutes. Cool the samples to 77F and record their pH values. I must have missed the part about adding the baking soda though. Can someone fill me in?

 

[Silver_Is_Money]

I'm going to mix 80g of malt with 200ml of 122F RO water in a flask. And then spin the test mash on a stir plate for an hour. Taking a sample at 30 minutes and 60 minutes. Cool the samples to 77F and record their pH values. I must have missed the part about adding the baking soda though. Can someone fill me in?

The baking soda additions (and pH's) come after measuring the first (or DI) pH. The subsequent baking soda pH's are needed to establish the titration factor(s).