Too many of my recent brews have been brownish in colour, so it was now time to make something really dark. The intention was to make a normal strength robust porter at around 6.0% abv, but the mash efficiency was pretty good for a dark beer and it came out as an imperial porter. Things could have been worse.
I have had terrible mash efficiencies when making dark beers earlier. Fortunately things went better this time.
An extraordinarily fine crush made by Frode's Crankandstein (or is it Crankenstein monster?) must have contributed somewhat, but not enough to replace the Barley Crusher though. I noticed a lot of dry grain balls in the mash as I doughed in, but a few minutes of stirring made them go way. So it was clear that the crush was much finer than what I have had earlier. There were no hints of any run-off problems, so the crush is fine. I also tried to sparge a little slower than at full speed making it more likely to extract more sugars. Each sparge took about 10 minutes, which is still a reasonably short time. I'll consider reducing the gap my own Barley Crusher for the next brew. It is currently set to the default.
The water in Oslo is extremely soft, very much like the water in Plzen, something that makes it perfect for light beers like pilsener. At the same time this makes it harder to make dark beers. Soft water is really the perfect brew water as it is a lot easier to add minerals than it is to take them out. So to emulate the water of other famous brewing cities one can just add minerals.
I made a porter with 500 grams of chocolate malt and black malt about a year and a half ago, which turned into something very harsh and astringent. I blame the pH of the water. A low pH means a lower mash efficiency and extraction of undesired characteristics like tannins. This time I added 2.5 ts calcium carbonate and 2 ts of 5.2 powder. The recipe also use dehusked dark malts, which should keep the sharp edges out of the beer. I also added the dark malts 45 minutes into the mash, giving the base malt a better chance of converting itself before the pH gets lowered by the dark malts.
The batch was brewed 2007-04-16.
All grain, batch sparge
80 EBC (Black)
5000g Pale malt
1000g Munich malt
500g Amber malt
400g Crystal malt, 300 EBC
400g Crystal malt, 130 EBC
250g Carafa I, debittered chocolate malt
250g Carafa II, debittered black malt
68C, 60 min
76C, 10 min (mashout)
30g Warrior pellets, 13.8%, 60 min
20g Warrior pellets, 13.8%, 10 min
Nottingham, 2 packs, dry yeast, best before date 2007-01-15 and 2007-12-01.
OG: 1.068 FG: 1.017 (estimated) abv: 6.7%