How to calculate the BC and pHDI of malts which have zero Diastatic Power ...

[Silver_Is_Money]

... whereby malts/grains with zero diastatic power can not be stand alone mashed so as to reliably assess either their pHDI or their BC.

Let's begin: (bear with me, as this is a long one)

1st: Establish the BC for a 'Standard Candle' base malt:

Let's use the example of a Pale Malt as our 'Standard Candle':

1) Grind ~60 grams of our Pale Malt in a well cleaned and well dried and well emptied Coffee Grinder.
2) Add 50 grams of this pulverized malt to 200 mL of distilled or DI water.
3) Mash at ~67 degrees C. for 1 hour
4) Cool to 20 degrees C. Do not decant, but rather leave the grist in with the Wort.
5) Measure the pH at 20 degrees C. with no stirring. Wait 30 seconds for full probe stabilization.
6) Record the pH as the 'Standard Candle pHDI'
7) Titrate the sample (grist plus Wort) to pH 5.40 with 0.1N HCl or 0.1N H2SO4 or 0.1N HNO3, with stirring after each small acid addition, but allowing the pH probe to sit undisturbed in the wort/grist for 30 seconds to stabilize for each reading. Stop titrating at pH 5.40.
8) Multiply the mL's of titrant required by 0.1 to compute the mEq's of acid titrant required.

Hypothetical Example:
pHDI = 5.73
Titrant required to hit pH 5.40 = 6.7 mL
mEq's of acid titrant = 0.1 x 6.7 = 0.67 mEq's

9) Delta-pH = mEq's/(BC x Kg.) [where 50 grams of grist mashed = 0.050 Kg.)
10) 5.73 - 5.40 = 0.33 = Delta-pH
11) 0.33 = 0.67/(BC x 0.050)
12 Solve for BC: And poof, BC = 40.6

The BC (Buffering Coefficient) of our 'Standard Candle' base malt is calculated to be 40.6 mEq/Kg_pH. This means that it takes a calculated 40.6 mEq's of acid to move 1 Kg. of our 'Standard Candle' base malt downward by 1.00 pH points within a DI water mash. Or 13.398 mEq's to move 1 Kg. downward by 0.33 pH points. (whereby 0.33 x 40.6 = 13.398)

So now we have established that our 'Standard Candle' base malt has a pHDI of 5.73 and a BC of 40.6

Lets consider Black Patent malt next.

Black Patent malt has no diastatic power, so we can't (reliably, at least) test mash it alone. We will therefore need to mash it along with our 'Standard Candle' base malt, and then extract Black Patent's pHDI and BC from within that groundwork.

Lets begin:

1) Grind 30 grams of the Black Patent plus 30 grams of the 'Standard Candle' base malt 'together' in a well cleaned and well dried and well emptied coffee grinder.
2) Add 50 grams of this pulverized malt blend to 200 mL of distilled or DI water.
3) Mash at ~67 degrees C. for 1 hour
4) Cool to 20 degrees C. Do not decant, but rather leave the grist in with the Wort.
5) Measure the pH at 20 degrees C. with no stirring. Wait 30 seconds for full probe stabilization.
6) Record the pH as the 'Blended Malts pHDI'. I'll presume here the pHDI will be below 5.40 pH.
7) Titrate the blended malts (grist plus Wort) to pH 5.40 with 0.1N NaOH, with stirring after each small NaOH adition, but allowing the pH probe to sit undisturbed in the wort/grist for 30 seconds to stabilize for each reading. Stop titrating at pH 5.40.
8) Multiply the mL's of titrant required by 0.1 to compute the mEq's of basic titrant required.

Hypothetical Example:
pHDI = 5.01 for the blended malts
NaOH titrant required to hit pH 5.40 = 10.9 mL
mEq's of basic titrant = 10.9 x -0.1 = -1.09 mEq's (minus because the titrant is basic)

9) We know from the above example for our 'Standard Candle' that 50 grams (0.050 Kg.) of this base malt required 0.67 mEq's of acid titrant whereby to hit pH 5.4.
Therefore: 25 grams of the 'Standard Candle' are the basic equivalent of -0.67/2 = -0.335 mEq's of basic titrant.
10) -1.09 mEq's of NaOH + -0.335 mEq's of 'basic equivalent' = -1.425 mEq's required to move 25 grams of Black Patent Malt alone to pH 5.40 [but I'm jumping ahead a bit here so:]
11) (5.40 - 5.01) = -1.09/(BC x 0.050)
12) BC_Blend = -55.9
13) -55.9 + 40.6 = -15.3
14) Our estimated BC for our Black Patent malt = -55.9 + -15.3 = -71.2
15) And we know from step #10 above that -1.425 mEq's are required whereby to move 25 grams of Black Patent Malt alone to pH 5.40
16) Therefore:
Delta pH = -1.425/(-71.2 x 0.025)
Delta-pH = 0.80
5.40 pH - 0.80 = 4.60 pHDI for our Black Patent malt

Double Checking on the BC:
Delta-pH = mEq's/(BC x Kg.)
(4.60-5.40) = 1.425/(BC x 0.025 Kg.)
-0.80 = -1.425/(BC x 0.025)
-0.80(0.025*BC)=-1.425
-0.02*BC = -1.425
BC = -71.25 mEq/Kg_pH

Allowing for rounding error throughout everything above, -71.2 ~= -71.25 ~= TRUE (or rather, a close check with an average BC of 71.225 allowing for all roundings and hypothetical presumptions)

So therefore we can now conclude that our lot of Black Patent malt when standing all alone has a pHDI of ~4.60 and a BC of ~71.225

NOTE: I cobbled this together rather quickly. So as I always say (while plagiarizing Ronald Reagan), "trust but verify". I would thereby well appreciate if someone checked my work.

 

[Silver_Is_Money]

You can mash Caramel/Crystal type malts (other than Carafoam/Carapils types) straight up whereby to compute their pHDI and BC since they are effectively pre-mashed.

 

[TheMadKing]

Can you do a test mash by adding some amylase enzyme directly? Or does that interfere with the results?

 

[soccerdad]

High school chemistry classes should teach this stuff. I would have paid attention if I knew the experiments related to beer making.

 

[Silver_Is_Money]

Can you do a test mash by adding some amylase enzyme directly? Or does that interfere with the results?

I would think that adding amylase enzyme would indeed permit the mashing of a malt/grain with insufficient diastatic power for a self mash, but it would only yield correct pHDI and BC values if amylase enzyme itself was totally pH neutral.

Edit: Albeit that with rethinking this, amylase enzyme would be present within any mash. So if moderated properly it should likely work. And data gleaned from a direct mash is always to be preferred over a blended mash with data extraction as presented above.

 

[ep_brew]

I've been thinking about this topic recently and some questions came up in my mind; I'm curious of your opinion. I was reading Stout by Michael Lewis and he shows a graph of pH values measured from CWE malt samples. The values on his graph lined up nicely with the Briess pH values in How To Brew 4th ed. CWE is a room temperature "mash" with the enzymes deactivated and John Palmer says "Neutralization of alkalinity by the chemical reactivity of calcium and magnesium ions does not require enzyme activity". I'm wondering if anyone has tested holding the malt at room temp vs mash temp before checking pH. Not having to set up water and ice baths would be nice.

 

[Silver_Is_Money]

Calcium and Magnesium ions are not added to 'Congress' mashes. So they would not b present whereby to acidify a wort which is basic (or exhibits a quasi-alkalinity) with respect to pH 5.40.

 

[ep_brew]

Right but malt has some level of calcium intrinsically. Either way these titration mashes or congress mashes both use distilled water. Also I don't believe CWE (Cold Water Extract) is a congress mash. It's 5 grams fine grind malt in 50ml water at room temperature.

 

[ep_brew]

I'm a lay person when it comes to this stuff but another thing I've wondered is why we need to buy special 0.1N acids or bases for these experiments. Couldn't we just increase the malt to 100-150 grams and use standard 10% phosphoric acid from the brew shop? HTB says its 1.1 mEq/ml. And for the base couldn't I use baking soda which is 11.8 mEq/gram alkalinity. They wouldn't titrate to exactly 5.4 but you could use those values to determine buffering capacity right?

 

[ep_brew]

I'm just imagining a simple test where you put something like 100 grams of fine grind malt with a few hundred mil of room temp distilled water in a ball jar and shake it up, test the pH. Then add a ml of 10% phosphoric, shake and test pH again. Then do the calculations. That's why I was curious about the need for mashing temps for an accurate result.

 

[Silver_Is_Money]

Being a weak acid and a weak base respectively, they do not fully dissociate, and thereby their "strength" is variable (or 'relative') to pH. Only "strong" acids and bases have fixed mEq/mL strengths across a broad spectrum of pH's. When titrating you want to remove all potential variables. Plus the % concentration reliability of brewing grade Phosphoric Acid is terrible. And Sodium Bicarbonate is listed as being hygroscopic.

At specifically pH 5.40, I calculate:
10% Phosphoric Acid = 1.09032 mEq/mL
Baking Soda = -10.75162 mEq/gram

But the Ka's and pKa's (I.E., the dissociation constants) for these are both all over the board, and they are temperature variable as well as pH variable, so their strengths are not precise as for how I display them above. The problem is that dissociation constants themselves are not really constants.

 

[Silver_Is_Money]

I'm just imagining a simple test where you put something like 100 grams of fine grind malt with a few hundred mil of room temp distilled water in a ball jar and shake it up, test the pH. Then add a ml of 10% phosphoric, shake and test pH again. Then do the calculations. That's why I was curious about the need for mashing temps for an accurate result.

BC itself is highly pH specific, and thus a variable, as opposed to being a constant. If you wind up anywhere other than pH 5.40 after your proposed post acid or base 'fixed' mEq addition, the BC computed thereby is not valid for any other targeted pH than the one you achieved. I believe that this is one of the reasons why the scant data we have available to us as to BC's does not correlate well from one researchers BC data to another researchers BC data for 'nominally' the same malts/grains. We often don't know if the BC researcher even bothered to target pH 5.40. They certainly did not target pH 5.40 if they were merely adding fixed mEq's of acids or bases.

 

[Silver_Is_Money]

Of course I did not help things at all when I stated this above:

The BC (Buffering Coefficient) of our 'Standard Candle' base malt is calculated to be 40.6 mEq/Kg_pH. This means that it takes a calculated 40.6 mEq's of acid to move 1 Kg. of our 'Standard Candle' base malt downward by 1.00 pH points within a DI water mash. Or 13.398 mEq's to move 1 Kg. downward by 0.33 pH points. (whereby 0.33 x 40.6 = 13.398)

Although it would be factually true for our hypothetical 'Standard Candle' base malt example that 13.398 mEq's will lower the pH pf 1 Kg. of this "specific right down to the lot, age, and storage condition" malt from 5.73 to 5.40, it will not very likely prove to be factually true that 40.6 mEq's of acid when added to 1 Kg. of this same malt will lower its pH to 4.73. 'Linear' thinking such as this is done merely for convenience and convention. Malt titrations are not linear.

PS: After openly confessing this sinful error of convenience, I'm feeling better already.

 

[ep_brew]

Thanks for the follow up. For homebrewing (not research) the BC numbers I've seen in books and online always seemed linear enough across the narrow range we brew at. I did see where there was some bad phosphoric recently but ultimately if you can't trust the acid at the brew shop how do you adjust your mash?

I didn't' mean do derail any conversation around your exact method, it's very through. I'm really just wondering if I could measure the pH of a cold mash instead of going through a long heating and cooling process, because I like things to be easy. Your post stated you need to mash your sample at 67c for an hour and and the roast needs base malt so I thought you might be able to inform me as to why that's necessary to determine distilled pH.

Here's what I'm ultimately trying to accomplish. I want a chart for UK malts - base, crystal and roast just like the Briess chart in HTB 4e page 351

I'm not able to find distilled pH values for those malts online so I thought I was going to have to measure them myself. As for the BC I was probably just going to average the Briess numbers for each category (base, crystal, roast) and apply those to be close enough for homebrewing instead of titrating every malt.

 

[Silver_Is_Money]

Here's what I'm ultimately trying to accomplish. I want a chart for UK malts - base, crystal and roast just like the Briess chart in HTB 4e page 351

I don't have this book. Might you scan or photograph this chart and post it here please?

 

[ep_brew]

I highly recommend How To Brew 4th ed. It gives an overview of pretty much everything in homebrewing. Its better than the 3rd edition and much, much better than the Water book as an introduction to water and mash pH.

I haven't brewed since COVID started but I've been reading a lot. So I thought I'd start back up brewing by applying some of what I'd learned.

I like the chart because I'd like to have an idea of what I'm doing. Even if it's not exact, I know how to adjust to get to where I need to be. I don't like magic numbers from mash calculators (that's not directed at you, just my personal preference). So it gives this chart as an example, not as a standard for all malts in all conditions. I imagine you already have the data for this chart.

I compared the pH values in HTB to the chart in Stout (I assumed they used NA malt since he was in California), that's when I thought I might be able to measure pH of other malts without raising the malt to mash temp.

I'm planning to do an experiment this weekend where I'll mash a sample hot then do a cold water steep and compare the values. So I'll have an answer to my question in a few days.

 

[Silver_Is_Money]

Thanks much @ep_brew!

For comparison purposes, if you set 'Mash Made Easy' (the 'Standard Version' with the Lovibond color scale for the grists malts/grains/adjuncts) to 2.20462 Lbs. (1 Kg.) of a single malt, and zero out all mineral additions, and start with zero minerals source water, and lastly set the "Grist Buffer Multiplier" value to 1 (I.E., set it for a highly pulverized grist, as for a Congress Mash) you can then read MME's comparable mEq/Kg values for any given grain input by looking at the value as seen within the cell at the right titled "Mineral Modified Grist mEq’s @ Target pH".

Then lastly play with the 'Grist Buffer Multiplier' value a bit to see how it impacts MME's internally calculated mEq/Kg values. This multiplier simulates crushes other than 'pulverized', such as would be used in real world brewing. Much literature speaks to the difficulty in getting Congress Mash data to correlate with real brewing world data, and this multiplier brings what would otherwise be effectively Congress mashes down to ones real world crush levels. A calculator to assist with this is provided for guidance as to how to set the "Grist Buffer Multiplier" so as to match your level of crush. Just enter your 'Mill Gap' into the 'calculator' cell asking for it and see the multiplier suggestion, then transfer it to the "Grist Buffer Multiplier" cell. There is full flexibility here whereby you can freely choose a multiplier value other than MME's 'calculator' suggested one.

 

[ep_brew]

Well I completed the cold water steep vs. mash temp and 90+ pH measurements later I think I have the answer.

I tested 4 malts both pulverized and crushed at 1 mm under three conditions; room temp stirred, room temp shaken and mashed. All tests used distilled water.

The pH of the cold water steep sample increases over time and level of agitation. While you can ultimately obtain a pH value the same as the mashed sample, the rate at which the pH increases is variable among malts, stirring vs shaking and pulverized vs 1 mm crush. While I could say shaking a sample for a certain amount of time will get you within so many tenths of the mash pH, you could get just as close by using an average pH for that type of malt.

FYI, Here are some mash pH values I collected.
1 mm crush. 4:1 liquor to grist. 67c mash temp. Held for 30 minutes. Cooled over 8 minutes. pH measured at ~23c

Briess Brewers - Lot A: 5.71
Briess Brewers - Lot B: 5.70
Muntons Maris Otter: 5.69
Muntons Planet Pale: 5.74

My meter is an Extech PH100 with Apera calibration buffers. I was meticulous in cleaning everything with distilled water and calibrating between measurements so I'm very confident in these numbers.

Looking at the numbers I measured vs. the chart I posted above and other internet pH values for malts was a reminder that if you really want to know the pH of a malt, you just need to measure it yourself.

 

[Silver_Is_Money]

Nice work @ep_brew ! Are you planning to titrate to pH 5.4 and compute BC's?

 

[Silver_Is_Money]

@ep_brew, would you agree that mashing is the quickest and most consistently reliable method whereby to achieve pHDI and BC's?

NOTE: pHDI's must be accompanied with BC's whereby to derive malt acidities. Unfortunately, one value without the other will not tell you much of anything.

 

[ep_brew]

I would say mashing is the most realistic and repeatable. I performed the mash tests in duplicate and I was within 0.01 each time but I followed the same schedule. Same mill gap, 67c dough in, hold at temp, stir at 15 min, cool at 30 over 8 min and measure at 23c.

If you want an example of how process can change numbers, consider this. Now this was a cold steep experiment. I put Briess Brewers - Lot A through an extreme experiment. The minimum pH I recorded for the pulverized grist was 5.53 after stirring then measuring at 5 min. Then I shook a pulverized sample intermittently and tracked the rise in pH until it wouldn't go any higher. It took 4 hours and 15 minutes and plateaued at 5.90.

Now I could tell you truthfully that the distilled pH of that malt was any number in between depending on what time you measured. So I think homebrewers who want to know these values need to measure in a way that's similar to how you use the malt and that's by mashing it. Or use a standardized method like the one you proposed. Just be consistent. I had a dream it could be easier but unfortunately not.

I don't know that I'll do anymore experiments, it was a lot of work and I didn't even end up with beer at the end. I was just trying to make things easier for myself.

I'm more of a pragmatic person so I think when I buy my next sack of pale malt, I'll measure the pH or just assume a 2-3 Lovibond base is 5.7. Then brew a single malt beer, and make an educated guess at the BC when I do the acid calculations. Then measure the actual mash pH. I'll have good enough for homebrewing numbers after that I can apply to future batches from that sack. Then make a beer with crystal malt and compare my numbers. Things like that.

Or I can use your spreadsheet since I have a better idea of how it works now.