Going Dark

In the last post I discussed an experiment involving dark beers. I wanted to evaluate three mash methods involving the use of dark roasted grains, and how adding carbonates to the mash water might influence the flavor of the final beer. The recipe I chose was a dry stout, and the grain bill consisted of pale malt, flaked barley and about 12% roasted barley. The home of dry stout is Ireland, and Dublin in particular. Most references suggest that the Dublin water has a carbonate hardness level exceeding 200 ppm, compared to my water that is typically 60 to 70. Note the carbonate hardness does not tell the whole story, residual alkalinity is a better measure as it accounts for the impact of the calcium hardness on mash acidity (the more calcium, the more the pH pf the mash can drop). The RA value for Dublin is often shown to be over 100, up to 125 (the higher the RA, the more it balances the acidity of the dark grain). My RA usually hovers around 30. How much calcium carbonate do I need to add to my mash?

In order to make the best estimate, I surfed on over to the Water Chemistry Calculator at Brewer’s Friend.  This calculator was devised by Kai Troester and based on experiments he conducted on grain color and mash pH. It is a very detailed beast, but if you carefully enter your water chemistry and grist information, then it will nicely calculate your expected mash pH (which should be about 5.5).  And here is where I got my shock: my water was fine as it was, nothing need be added.

How’s that?

Well Kai’s work has shown that dark caramel/crystal grains have much more effect of water pH that dark roasted grains.  In fact if I had used 60 lovibond crystal in lieu of the roasted barley my pH would have been around 5.0, which is far below optimum.  I would love to have confirmed this with a pH meter, but those things are the devil’s work.  They fail more often than first love, and I cannot convince myself to shell out $50 or more on another one of them.

I should note that all of this is controversial.  Some water chemistry calculators work strictly off the expected beer color, and these are ones that, in my experience, tend to suggest some pretty high levels of carbonates.  For instance, John Palmer’s water spreadsheet on his website would recommend an RA of well over 200 for the beer I just made.  While his spreadsheet is quite useful in many ways, that high an RA seems a bit overboard.

Did I mention how easy it is to learn water chemistry?

Post a comment or leave a trackback: Trackback URL.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: