Simple do it yourself Mash pH adjustment

[Silver_Is_Money]

Malt's ballpark mEq requirements by the pound for the conditions of no-sparge, and 8 mg/L Alkalinity, and 75 mg/L Ca++ ion, and a 0.032" mill gap crush, and a Target Mash pH of 5.40.

Pilsner Malt: 3.5 mEq/Lb. (as Acid)
Pale Malt: 3.0 mEq/Lb. (as Acid)
Brewer's Malt: 1.5 mEq/Lb. (as Acid)
Light Munich Malt: 0.6 mEq/Lb. (as Base)
Medium Munich Malt: 3.5 mEq/Lb. (as Base)
Dark Munich/Biscuit/Victory Malt: 5.6 mEq/Lb (as Base)
Brown Malt: 10 mEq/Lb (as Base)
10L Caramel/Crystal Malt: 5.1 mEq/Lb (as Base)
20L Caramel/Crystal Malt: 8.8 mEq/Lb (as Base)
40L Caramel/Crystal Malt: 13.5 mEq/Lb (as Base)
60L Caramel/Crystal Malt: 16.9 mEq/Lb (as Base)
80L Caramel/Crystal Malt: 19.8 mEq/Lb (as Base)
120L Caramel/Crystal Malt: 24.6 mEq/Lb (as Base)
140L Caramel/Crystal Malt: 26.8 mEq/Lb (as Base)
200L Light Chocolate Malt: 17.1 mEq/Lb (as Base)
300L Roasted Barley Malt: 19.8 mEq/Lb (as Base)
350L Chocolate Malt : 20.8 mEq/Lb (as Base)
500L Dark Roasted Malt: 23.3 mEq/Lb (as Base)

A Worked Through Example Follows:

Grist:
10 Lbs. Pale Malt
1 Lb. Biscuit Malt
0.5 Lb. 40L Caramel Malt

10 Lbs. Pale Malt: 10 Lb. x 3 mEq/Lb = 30 mEq Acid Addition Required
1 Lb. Biscuit Malt: 1 Lb. x 5.6 mEq/Lb = 5.6 mEq Base Addition Required
0.5 Lb. 40L Caramel: 0.5 Lb. x 13.5 mEq/Lb = 6.75 mEq Base Addition Required

30 mEq Acid Required - 12.35 mEq Base Required = 17.65 mEq 'Net' Acid Addition Required

At specifically pH 5.40, 88% Lactic Acid = 11.4515 mEq/mL

17.65 mEq Acid Required ÷ 11.4515 mEq/mL = 1.54 mL of 88% Lactic Acid

Final Answer = Add 1.5 mL of 88% Lactic Acid to mash @ ~ pH 5.40

 

[tracer bullet]

Nice! And, interesting.

Pilsner Malt: 3.5 mEq/Lb. (as Acid)
Pale Malt: 3.0 mEq/Lb. (as Acid)
Brewer's Malt: 1.5 mEq/Lb. (as Acid)

Stating what is probably obvious, I've found that it's this that gets me each time. If I brew a porter recipe several times for example, I can tweak the exact amount of brown or chocolate in it with hardly a difference in the mash pH. But if I change Maris Otter brands, or to Pale, or 2-Row or something, it is up in the air what'll happen. Maybe no change, maybe a big change. I've learned when trying to develop my own recipe to find a base malt and stick with it, otherwise the mash pH is unpredictable. And cross my fingers that my preferred base malt doesn't change too much one season to the next, or the LHBS doesn't pour something different into the bin.

If I had an infinite amount of time I'd develop a database of base malts and their resulting pH's.

Hopefully this is on topic... Curious if you have tried such a thing? I've gathered what I can online but it's spotty at best.

 

[brewbama]

good stuff.

Can you explain why I don’t need to add lactic acid to my mash to hit ~ 5.4?

Based on G Strong’s method:
I use RO water.
I routinely heat strike water, deaerate w/ yeast+sugar, add Brewtan B, and underlet grist.
I only mash the grains that require it.
I withhold roast malts and dark(er) crystal (over ~60°L) until mash out.
I add 1 tsp CaCl or gypsum (or a combination of the two = 1 tsp) per 5 gal strike and 1 tsp Ascorbic Acid to the grist before adding it to the MLT.
No sparge.

Is it the mEq/mL for Ascorbic Acid? Or mEq/mL for CaCl/gypsum? Or both?

 

[Silver_Is_Money]

The mEq for Ascorbic Acid at a pH of 5.40 is 5.46 mEq/gram.

Within exclusively the mashing phase (step) of a grist passed through a mill gap of 0.032" as to crush:

Ca++ (or rather the H+ which it liberates) is about 5.72 mEq/gram (where grams are the grams of the Ca++ ion alone, and not as grams of added CaCl.2H2O or CaSO4.2H2O)

Mg++ (or rather the H+ which it liberates) is about 1.74 mEq/gram (where grams are the grams of the Mg++ ion alone, and not as grams of added MgSO4.7H20)

* Ca++ and Mg++ further assist with additional pH drop later on, throughout the boil.

 

[Silver_Is_Money]

When you finally add the late addition roasted malts back in you are acidifying your tail end of the mash Wort, likely without realizing it. Mash pH is best read at mash completion, and not before.

And you are not getting the full flavor impact of the dark malts you paid for. Less return on the dollar...

 

[brewbama]

does this account for Ca in the water reaction with phosphates in the grain husks to release phytic acid, which lowers the mash pH naturally?

 

[Silver_Is_Money]

Ca++ reacting with Malt Phosphates to liberate H+ ions as stated in post #4.

 

[Silver_Is_Money]

To bring 1 Lb. of 'nominal' Acid Malt to ~pH 5.40 under the above defined brewing conditions requires the addition of ~147 mEq of a base.

Baking Soda is ~ 10.7 mEq/gram in the vicinity of pH 5.4.

~147/~10.7 = ~13.7 grams of Baking Soda.

 

[Silver_Is_Money]

Nice! And, interesting.



Stating what is probably obvious, I've found that it's this that gets me each time. If I brew a porter recipe several times for example, I can tweak the exact amount of brown or chocolate in it with hardly a difference in the mash pH. But if I change Maris Otter brands, or to Pale, or 2-Row or something, it is up in the air what'll happen. Maybe no change, maybe a big change. I've learned when trying to develop my own recipe to find a base malt and stick with it, otherwise the mash pH is unpredictable. And cross my fingers that my preferred base malt doesn't change too much one season to the next, or the LHBS doesn't pour something different into the bin.

If I had an infinite amount of time I'd develop a database of base malts and their resulting pH's.

Hopefully this is on topic... Curious if you have tried such a thing? I've gathered what I can online but it's spotty at best.

Yes, unfortunately base malts can have a high degree of mEq unpredictability. By type. By growing region. By year grown. By lot. By regional weather conditions. By soil analysis. Etc....

 

[Silver_Is_Money]

To bring 1 Lb. of 'nominal' Acid Malt to ~pH 5.40 under the above defined brewing conditions requires the addition of ~147 mEq of a base.

Baking Soda is ~ 10.7 mEq/gram in the vicinity of pH 5.4.

~147/~10.7 = ~13.7 grams of Baking Soda.

This suddenly reminded me of a time a few years back when a guy posted that he just realized he had mistakenly added an unwanted pound of Acid Malt to his now mashing grist, and he was asking what could be done rapidly to alleviate the mistake. I'm not one to advise adding a whopper load of sodium via adding 13.7 grams of Baking Soda as a fix, and I also generally advise against adding Calcium Hydroxide. But in a panic case such as this the best solution by which to rapidly negate the error just might be to quickly and very efficiently stir ~6.4 grams of Ca(OH)2 [Calcium Hydroxide] into the mash.

 

[brewbama]

A cpl more (possibly dumb) questions (pardon me): is there a lookup table for the various grains/malts and various other acids/bases that the average homebrewer can access?

For example flaked barley is not listed in post #1 but used in a general Stout recipe (Pale malt, Flaked Barley, and Roast Barley).

if I mash 6.5lb Pale malt and 1 lb flaked barley I get 9.75 mEq acid required for the Pale but X required for the barley.

Then after the initial mash is complete I add .3125 lb debittered roast barley, and .5 lb choc to the mash for 30 minutes. I see roast and choc above for 17.68 mEq base required (if debittered roast ≈ roast above but I doubt it is).

 

[Silver_Is_Money]

Flaked Barley: ~2.1 mEq/Lb. (as Acid) for the given conditions outlined in post #1.

Debittered merely means dehusked. The acid content shouldn't change.

Baking Soda is a base which can counter the acid within dark roasted (etc...) malts.
Baking Soda @ 5.40 pH = 10.75 mEq/gram

 

[brewbama]

Thx. What is the original source of this information?

 

[Silver_Is_Money]

Thx. What is the original source of this information?

Me