Assessing individual grains for water adjustments

[Simonh82]

Is there a simple way of assessing individual grains for there contribution to mash pH and can the Bru n' water spreadsheet be adjusted on the basis of an findings?

I find that the suggested pH is usually too high for pale beers and too low for dark beers. For instance the last two beers I brewed were a golden ale which came in a 5.7 when I'd been aiming for 5.3 and a porter which came I at 4.9 when I'd been aiming for 5.3.

I should have twigged that something was up with the porter as I live in London which should have perfectly suited water but it was telling me to make quite large acid additions.

Anyway, both beers seem none the worse for it but I'd like to be able to dial it in correctly.

Can I steep some crushed grain and measure the pH then use this to calculate the contribution to the mash?

 

[ajdelange]

Is there a simple way of assessing individual grains for there contribution to mash pH...

Yes, there is. You make some test mashes to which different amounts of acid are added and plot the amount of acid added against the pH that the malt went to when that amount of acid was added. The result is a curve of mEq/kg vs pH. The pH when no acid is added (the water is DI) is the DI mash pH. If your base malt has a pHDI of around 5.7, for example, and you want to realize a mash pH of 5.4 you would then consult the curve for this malt to see how many mEq of acid are needed to get to pH 5.4 for each kg of this malt used. You then do the same for all the other malts and calculate the amount of acid required to bring the mash water to the desired pH. The sum of the acid requirements for each of the mash components is the total amount of acid required.

...and can the Bru n' water spreadsheet be adjusted on the basis of an findings?

Sort of. You can fool it by telling it that the malt in question is of a darker (makes the program think it is less alkaline) or lighter (makes the program think it is more alkaline) color than it actually is.

I find that the suggested pH is usually too high for pale beers and too low for dark beers. For instance the last two beers I brewed were a golden ale which came in a 5.7 when I'd been aiming for 5.3 and a porter which came I at 4.9 when I'd been aiming for 5.3.

Spreadsheets that rely on grain color as a source of information about grain characteristics can't be expected to be very precise as two malts of the same type and color may have DI mash pH's that differ by 0.2 or more.

I should have twigged that something was up with the porter as I live in London which should have perfectly suited water but it was telling me to make quite large acid additions.

Given the above one should take any spreadsheet's recommendations with a grain of salt. A test mash is always the best insurance.

Can I steep some crushed grain and measure the pH then use this to calculate the contribution to the mash?

Yes, as noted above. But if you wan't robust pH estimates you will have to do this several times for each malt and the labour gets quite burdonsome. A test mash is much simpler.

If you want details there is an MBAA TQ article which spells them out.

 

[Simonh82]

Thank you, this is really useful. What is the smallest mash you could get away with when doing this procedure?

 

[ajdelange]

I use 40 grams of finely milled grain with 100 mL of hot water in a stainless steel beaker which is immersed in a constant temperature water bath. I use acid which is of known and carefully calibrated strength which is dispensed from a cartridge by a device which reads the number of mEq directly (Hach Digital Titrator).