Recipe: Cory King's Big Imperial Stout

This recipe is based on King's original homebrewed imperial stouts. He has tweaked it here and there over the years, but this is the foundation of his recipes and method for brewing big, heavy imperial stouts at Side Project.

It is not an easy beer to brew or to ferment. Expect a long and inefficient brew day, with everything geared toward highest gravity and heaviest body. Stuck sparges are possible bordering on likely. Note the long boil. Pitch an ample, healthy yeast starter, and oxygenate thoroughly. Then give it plenty of time.

Batch size: 5 gallons (19 liters)
Brewhouse efficiency: 60%
OG: 1.134
FG: 1.044
IBUs: 90
ABV: 12.4%

MALT/GRAIN BILL
16.9 lb (7.7 kg) two-row pale malt
5.75 lb (2.6 kg) flaked oats
2.6 lb (1.2 kg) Carafa II
1.7 lb (771 g) Caramel/Crystal 60L
1 lb (454 g) black malt
14.4 oz (408 g) roasted barley

HOPS & ADDITIONS SCHEDULE
12 oz (343 g) brown sugar at start of boil
10 oz (283 g) lactose at start of boil
3.4 oz (96 g) Magnum [12% AA] at 60 minutes

YEAST
Fermentis Safale US-05 American Ale Yeast or equivalents

DIRECTIONS
Mill grains and mash at 150°F (66°C). Collect first runnings, aiming for a pre-boil gravity of about 1.095-1.100. (Pre-boil volume may be about 8 gallons/30 liters, but in this case gravity takes priority over having enough enough liquid.) Boil for 4 hours or even longer, adding sugars and hops according to schedule. Chill wort to 65°F (18°C), pitch plenty of yeast or an ample starter, and oxygenate thoroughly. Ferment at 65°F (18°C) for several weeks, until fermentation is complete.

BREWER'S NOTES

About mash temperatures: "I thought about that, and since we have so many recipes, I don't have a go-to," King says. "Ideally, Id say 155°F, but most homebrewers are going to struggle with attenuation on a beer like this, so 150°F might be better for them."

Because of the large amount of grain, Side Project mashes thick (about 1.1 qts/lb) and does what is essentially a batch sparge, adding only enough sparge water at the end to keep the lauter going. Know your water and monitor mash pH, keeping it above 5, and aiming for 5.3 or even a bit higher. "Our water here is St. Louis is awesome for dark beer production," King says. "Watch your mash pH. Boil, boil, and boil more." Boiling can go 4–8 hours, with hops going in when one hour is left. Optionally, add malt extract to reach target OG. 

The yeast should be a "clean, high-attenuative workhorse," King says, "or maybe Nottingham if you like a little dark fruit with age."