Bru'n Water - Malt Acid Content Relationships

[ScrewyBrewer]

After reading Martin's Water Knowledge page I was surprised to see there was no category for Wheat malt in the Malt Acid Content Relationships table.

Wheat malt seems to be an outlier, having a DI pH value of 6.04, 0.32 points higher than 2 Row malt having a DI pH 5.70. When formulating a brewing water profile, for a wheat beer recipe using 45% Wheat malt and 55% base malt, it seems the Bru'n Water pH prediction would benefit from including an entry for Wheat malt in the Malt Acid Content Relationships table.

Since the mEq/lb acid contribution of base malt is (0.28*Lovibond Rating) wouldn't it be fairly easy to add Wheat malt too?

 

[mabrungard]

I've experienced the same thing. But I haven't formulated an acidity relationship for wheat malt. It probably should be added!

 

[ajdelange]

Weyermanns wheat malt has a DI pH of 6.07, a first buffering coefficient of -44.9 and a second coefficient of -6.0. IOW in going to mash pH equal to pHz you will need -44.8*(pHz - pHDI) -6*(pHz - pHDI)^2 mEq of acid per kg of this malt. Caveat: this data is based on measurement of a single lot of this product.

Since the mEq/lb acid contribution of base malt is (0.28*Lovibond Rating) wouldn't it be fairly easy to add Wheat malt too?

A malt yields acid only when the mash pH is greater that the dipH, in the case of Weyermanns wheat, that is greater than 6.07. Weyermans is 4.5 EBC or about 2.2 °L. Thus its 'acid yield' by this rule is
0.28*2.2 (°L) *2.2 (kg/lb) = 1.3552 mEq/kg. No pH shift is indicated so this by itself is meaningless. From above the 'acid yield' slope at pH 6.07 is 44.8 mEq/kg•pH and thus 4.48 mEq/kg for each tenth pH unit above 6.07 e.g. in a mash at pH 6.17 it would yield 4.48 mEq/kg. So I don't really know what the 0.28*°L refers to but it doesn't seem applicable to this malt or indeed most malts which have first buffering coefficients similar to this malt's.

 

[ScrewyBrewer]

Weyermanns wheat malt has a DI pH of 6.07, a first buffering coefficient of -44.9 and a second coefficient of -6.0. IOW in going to mash pH equal to pHz you will need -44.8*(pHz - pHDI) -6*(pHz - pHDI)^2 mEq of acid per kg of this malt. Caveat: this data is based on measurement of a single lot of this product.



A malt yields acid only when the mash pH is greater that the dipH, in the case of Weyermanns wheat, that is greater than 6.07. Weyermans is 4.5 EBC or about 2.2 °L. Thus its 'acid yield' by this rule is
0.28*2.2 (°L) *2.2 (kg/lb) = 1.3552 mEq/kg. No pH shift is indicated so this by itself is meaningless. From above the 'acid yield' slope at pH 6.07 is 44.8 mEq/kg•pH and thus 4.48 mEq/kg for each tenth pH unit above 6.07 e.g. in a mash at pH 6.17 it would yield 4.48 mEq/kg.

So I don't really know what the 0.28*°L refers to but it doesn't seem applicable to this malt or indeed most malts which have first buffering coefficients similar to this malt's.

Thank you for the breakdown AJ, I know you have provided me with the method used to answer the question I posed. As usual, it will take me a while to chew on the formula and digest the information. Adding wheat malt to the mash will raise the mash pH, since most barley base malt falls in the 5.6 to 6.0 DIpH range.

 

[ajdelange]

Yes, of course it will! I saw 6 in front of me and wrote as if it were 5.6. Doh!!