7 March 2009

posted by benjy edwards

We’re wrapping up this run of the yeast with a bruiser of a beer, an imperial stout.  The best way to reuse yeast is to brew the batches in order of their original gravity, starting with the lowest.  This is because the higher ABV beers stress the yeast with the amount of alcohol that is produced, which is toxic to yeast, just like it is with people.

Our target gravity was 1.080, so not that strong by imperial stout standards.  The recipe was forumulated after researching many commercial and homebrewed examples, including North Coast’s Old Rasputin, B.O.R.I.S. from Hoppin’ Frog, Great Divide’s Yeti, an imperial stout from Brew Your Own magazine, and our own previous batch of imperial stout brewed in early 2006.

Along with Maris Otter, we added generous amounts of crystal and Special B, chocolate malt, black malt, and roast barley, plus aromatic malt, brown malt, and flaked oats.  The total grain bill was 38 pounds, which just barely fit into the mash tun at a water to grist ratio of 1.125 quarts per pound.  There was no room for any rice hulls to help with filtration of the oats, but thankfully this was not a problem.  In the boil we added a pound of dark candi syrup and achieved an original gravity of 1.081.  Hops were Northern Brewer and Phoenix for bittering, along with some First Gold and Bramling Cross for flavour.  We’ll give this batch a week or two in primary followed by many months in secondary to age.  Christened Son of Satan, it will be ready to drink when the weather turns cool again in the fall.

The milk stout from last week was needed on tap, so we racked half of it to a corny keg, force-carbonated it, and tapped it immediately.  It turned out even better than the first time we brewed it, with plenty of sweetness to balance the roast malt character.  At only 4.2% it’s a great session beer.  The other half was racked to secondary along with a spare gallon put into a gallon growler.

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