Mash Acidification

[desitter]

Hello,

I've been playing around with Martin Brungard's "Bru'n Water" spreadsheet in preparation for first attempt at a stout (BCS Extra Stout). The general consensus in homebrew literature is that dark grain quickly push the mash pH below 5.2 (room temp reading), yet I'm finding with my relatively low alkaline water (23 ppm as CaCO3) that this is not the case, at least on the spreadsheet. Both Martin and Kai Troester suggest an optimal pH of 5.4 to 5.6 for stouts (5.3 - 5.5 otherwise), which is plumb where my predicted mash pH is (5.5), despite the dark grains and low alkalinity.

Below is my water composition:

Ca 7
Mg 5
Na 26
Cl 46
So4 7
HCO3 28
pH ~7.3

The grist is:

6.6kg Maris Otter (~2.5L)
340g Roast Barley (~500L)
280g Crystal 40
280g Crystal 80
230g Chocolate (~250L)

It could be that in practice the spreadsheet does not hold up. I guess I'm just surprised the pH reduction is not as dramatic as I was lead to believe. Does anyone have any experiences that would confirm or refute these results?

Cheers,

 

[TheWiggman]

The spreadsheet sounds like it's outputting the right results, might be worth posting it for others to double-check your inputs.
A dark malt by itself in little water will push the pH sub 5.2 but in in the proportions you've stated, with plenty of pale malt in there, won't. Above all though check your water pH manually and confirm the results. Supply water pH can vary quite a bit.

 

[manticle]

You really need to measure your mash, at least a few times to see how closely it might match.

As far as I'm aware, brun spreadsheet is based on empirical data but as with any brewing software it can only offer a prediction for your recipe and water. You have to do the testing yourself.

Certainly long before I played around with water I made delicious stouts and porters that didn't taste 'tangy' as an exceptionally low pH might suggest they would.

Also make sure you are inputting everything correctly.

 

[desitter]

Thanks for the responses guys, attached is the spreadsheet with all my water information. I've left the adjustment calculator at defaults for now.

View attachment (BCS) Foreign Extra Stout.xls

 

[antiphile]

In some ways, it's a matter of how involved you'd like to get in the process. After getting an accurate pH meter, the next 6 consecutive mashes included both an acid and a protein rest allowing particular attention to be paid to the pH midway through the protein rest. This allows any adjustments to be made if necessary, before the various amylases etc seriously kick in.

Then you get a good idea of how your water profile and salts generally act. I'll still do it occasionally just to check, or if using a recipe that's significantly different from the normal rotation or preferred/usual styles.

 

[Cervantes]

You could try the online calculator at www.brewersfriend.com to confirm your results.

Or download the EZ Water Spreadsheet. I find that gives very accurate results.

 

[desitter]

Thanks guys, I was planning on doughing in low to check pH for every new recipe. The brewersfriend calculator gives roughly the same mash pH, so I'm pretty confident the prediction is correct and that my assumption about mash acidity from dark malts was a little excessive.

Btw, does anyone know a good source of food grade slaked lime/pickling lime/calcium hydroxide? I'd just like to have some on hand should I ever need it. The Calcium Carbonate I have is just far to insoluble.

 

[mabrungard]

Your grist doesn't have that much roast in it and I'm not terribly surprised that the prediction wasn't very low. There are recipes with much more crystal and roast and they are more likely to depress the mash pH.

Do remember that another variable you can use in altering the mash pH is the water to grist ratio. A thinner grist has more water that has more alkalinity in comparison to the amount of malt. That can help boost the pH. You didn't mention the amount of water in your mash, but that does have an effect.

 

[dblunn]

Do remember that another variable you can use in altering the mash pH is the water to grist ratio. A thinner grist has more water that has more alkalinity in comparison to the amount of malt. That can help boost the pH. You didn't mention the amount of water in your mash, but that does have an effect.

Hi Martin, this is a little off topic, but when determining the water/grist ratio do you include every bit of water in the system. i.e. water that may be in hoses, pumps and HX in a HERMS setup?
Regards, Dave