Pumpkin Patch Imperial Stout

I have a more-or-less annual tradition of making a pumpkin beer, and I was looking for something a bit different this time around. Although to be honest, I’m always looking for something different on pumpkin beers! Each brewing year brings something unique–for 2017, I’m doing a pumpkin imperial stout!

The recipe is patterned after a BYO clone recipe for Southern Tier’s Warlock Imperial Stout, in the September 2017 issue. I scaled it down from 5 gallons to 3 gallons, because I didn’t really want a massive quantity of a ~10% abv beer. To up the malt complexity, I subbed in Vienna malt for the recipe’s 2-row, and subbed Warrior in for Chinook hops. Because this is such a high gravity beer, I assumed 70% mash efficiency (which turned out to still be a bit high). My local shop didn’t have WLP022 (Essex Ale yeast) in stock, so I opted for Mangrove Jack’s M15 (Empire Ale).

Pumpkin Patch Imperial Stout

  • 6.25 lbs. Vienna malt (Great Western)
  • 5 lbs. 2-row pale malt (Rahr)
  • 0.6 lb. flaked barley
  • 0.5 lb. de-bittered black malt (Dingemans)
  • 0.3 lb. caramel malt 60L (Briess)
  • 0.25 lb. Munich II malt (Weyermann)
  • 0.19 lb. chocolate malt (Briess)
  • 0.15 lb. rice hulls
  • 0.6 lb. pumpkin puree (homemade)
  • 1 oz. Warrior hops (15.8% alpha), 60 minute boil
  • 1 Whirlfloc tablet, 10 minute boil
  • 1 tsp. Fermax yeast nutrient, 10 minute boil
  • 1 pkg. Empire ale yeast (Mangrove Jack’s M15)
  • Cinnamon, vanilla, nutmeg, and ginger extracts to taste (3:1 ratio of cinnamon to others)

Target Parameters

  • Infusion mash to hit target of 150°, 60 minutes. Batch sparge.
  • Claremont tap water, with Campden tablet.
  • 1.095 o.g., 1.022 f.g., 9.7% abv, 70.5 IBU, 38 SRM, 3 gallons into fermenter

Procedure

  • I mashed in with 4.4 gallons of water at 162°, to hit a mash temperature of 151.4°. Given the big bulk of grain, the mash temperature held pretty well for the full 60 minutes.
  • After 60 minutes, I vorlaufed and collected the first runnings. I had a very slow run-off for this step.
  • I then added 2.45 gallons of sparge water at 185°, let it sit for 10 minutes, and vorlaufed again. I did a gentler (slower) vorlauf, which seemed to help with the sparging issue.
  • In total, I collected 4.9 gallons of water with a gravity of 1.065, for 67% mash efficiency. Given the high target gravity versus the volume of water, I’m not incredibly surprised. Nonetheless, I’ll want to remember to adjust efficiency accordingly for my next high gravity recipe.
  • I brought the wort to a boil and added the various hops, etc., at the designated time. After 60 minutes, I turned off the heat and chilled the wort to around 80°. I transferred while aerating, and then pitched the yeast directly.
  • Starting gravity was 1.085. I’ll be starting fermentation at 66°. I brewed the beer on 19 August 2017, and had visible yeast activity within 9 hours after pitching.
  • After around two weeks, I’ll add the appropriate spice extracts. I plan to make these myself, using a vodka infusion. Although the original recipe calls for clove extract, I am going to leave that out, because (as I read once from Gordon Strong) clove is too often an off flavor and might detract from the overall taste on the final product.
20170820_104709

Fermenting happily, ~12 hours after yeast pitching

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