Mash pH of high adjunct beers?

[toddk63]

I am using my home built spreadsheet to calculate acid additions to mash water to achieve mash pH of 5.3 to 5.5.

The spreadsheet is based on Palmer's where the final beer color is estimated and target RA is suggested. Then my water profile with calcium, magnesium and total alkalinity is used to determine the RA. Then using some formulas from A.J. deLange determine the meq of 1N HCl needed to achieve the final target RA.

This has worked very well for all malt beers of all colors (even with up to 20% adjuncts). I recently made a beer with 15% 2 row malt, 20% flaked wheat, and 65% cornmeal. The mash pH came out at 5.9 (too high) despite using the same calculation method. This got me thinking that the large percentage of adjuncts don't play like malt in the mash when it comes to pH even though I used a very low Lovibond value as input for the adjuncts (1 or 2).

I tested in the spreadsheet that the "malt" phosphates reaction with Ca/Mg to lower RA would be much less, assuming adjuncts had no phosphates. I did this by multiplying the Ca/Mg RA reduction by 0.15 (15% malt). This gave an extremely high acid requirement that made no sense.

So now I am looking for answers on this. Do adjuncts have some phosphates but not as much as malt? Is there any data on high adjunct DI mash pH? What else?

Thanks,

Todd K.

 

[Silver_Is_Money]

It is my understanding that the Palmer nomograph only works well for pointing you to the pH range at which a base malt will most likely dough in for a given source water. It seems to be pretty much useless for anything else. Palmer makes no mention of it in his latest book on water (which presents excellent details on how to determine mash pH via methods originally developed by people like Kai Troester and A.J. deLange), so perhaps even Palmer has finally abandoned it. ???

Is the nomograph the basis for the spreadsheet?

 

[toddk63]

I think I know the nomograph you speak of from his first book "How to Brew". I used the logic directly from his spreadsheet.

Low RA = (SRM)(12.2)-122.4
High RA = (SRM-5.2)(12.2)
SRM is from Morey formula

I have Palmer's water book. I will have to read it again. I think the "easy" answer is to determine through trial and error a "malt" phosphate factor of adjuncts .vs. base malt.