I HAVE BREWED THIS MANY TIMES AND IT IS ALWAYS A WINNER!!!
Key Points:
• Lots of yeast, don’t skimp on O2. To get the best-tasting, smoothest, and most age-worthy Imperial Stout out of your fermentation, start with a large population of healthy yeast cells and aerate/oxygenate the cooled wort well prior to pitching.
• Think about mash temp. Some folks like their Imperial Stouts a little more on the liqueur side of the sweetness spectrum, and that’s stylistically valid; I like mine a little more attenuated. Keep in mind that the high gravity and low hop rate will naturally make for a sweet impression on the palate no matter what.
• Caramelize the first runnings. All-grain brewers can exercise an option to caramelize the first, most concentrated and sugar-rich runnings from the sparge (see Mash & Sparge, step 8, below). This will increase color and complexity in the finished product.
• A little late hopping. Even though this is a malt-dominant beer, the merest suggestion of high-quality hops late in the boil will add complexity and interest to the profile without changing our drinking audience’s read on the maltiness of our Imperial Stout
• Stay cool. The key to keeping this potent ale from becoming headache juice is not to let the fermentation temperature rage out of control – slow and steady wins the race against undesired fruity esters and fusel oils. Cool fermentations are one reason to brew in the winter. One trick I like to employ is to over-chill the wort and pitch the yeast just a tad too cold; the yeast will generate its own heat as it begins to ferment.
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Prep
- Make a 2000 ml yeast starter prior to brew day – if needed.
- On brew day, collect strike water 36 quarts (I use RO water @ 1.3 quarts per pound, ratio may vary) and heat to 165 F (with grain temp at 68 F) Note, given the size of this grain bill, you may need to adjust for your particular mash tun volume and make up the difference with sparge and/or top-up water. Use a malty water profile.
- Mill the grains, or have it done for you at the shop.
Mash & Sparge
- Add grain to strike water and mix to achieve a uniform temperature of 148 F. After 15 minutes raise the temperature to 150-152 F. Rest the mash at this temperature for 60-75 minutes. Check for a ph of 5.6 and adjust as needed.
2 While the mash rests, collect and heat 12 quarts of sparge water to 170 F.
- Check to ensure all starches have been converted with iodine test.
- When the mash rest is complete, heat it to 168 F for mashout.
- Sparge and collect the wort in the boil kettle. Option: divert the first couple quarts of high-gravity runnings to a separate kettle or saucepan and boil for a few minutes (or longer) to caramelize and reduce, before adding back to the main wort prior to the boil.
Boil
- Collect enough wort (+/- 8.5 gallons) to account for evaporation from the long 120-minute boil.
- Bring the delicious, dark-colored wort to a boil.
- Boil for 60 minutes or until you have 7-3/4 gallons of wort. Then start your 60-minute timer!
- Add 1.50 oz. Nugget hops @ 60 minutes.
- Add 1.50 oz. Glacier hops @ 15 minutes.
- Add Yeast Nutrient @15 minutes.
- Add 1 Whirlfloc Tablet @ 15 minutes.
- Stir wort vigorously to create a whirlpool and precipitate out the trub.
- Insert wort chiller @10 minutes
- Cool it! Aim for a wort temperature around 60 F.
Fermentation and beyond
- Transfer the cooled wort to a sanitized fermenter, aerate with O2 for one minute, and add the yeast you prepared back in step 1. Use a blow off tube on this big beer.
- Depending on the yeast strain being used, aim for a fermentation temp of 63 F; depending on temp and yeast, fermentation for a beer of this gravity could take as long as 3 weeks to finish fermenting.
- Transfer the beer to a used bourbon barrel and add the Bourbon to barreled beer. The beer will show best after several months of conditioning in a cool, dark place.
- Transfer barrel aged beer to a keg or bottles. CO2 level of 2.75 volumes.
- Serve at 50-55 degrees F to show its best flavors and mouthfeel.
