Russian Imperial Stout with Bourbon Soaked Oak - Take II

Last year I attempted to clone the famous Goose Island Bourbon County Brand Stout which is a wonderfully intense whiskey barrel aged beer.  My version was pretty close (and very nice) but it didn't match the intense whiskey character of the original.  I've decided to try again this year to see if I could get a bit closer.

Last year I used 4 oz of white oak which I'd toasted at 450 F, charred, and then soaked in 90 Proof (45% ABV) Makers Mark whiskey for about 4 months.  Whiskey is aged in the barrel at closer to 60% ABV and then watered down to bottling strength.  This higher ABV (and stronger flavored) barrel strength whiskey is what BCBS is being flavored with.  I'm thinking this is probably the most likely culprit for the intensity difference between my clone and the original.

Over the last year I've been soaking oak (prepared the same way as last year) in a mix of 2/3 95% Everclear and 1/3 Spring Water which is about 63% ABV.  This is right in the range of cask strength whiskey.  I kept this in the attic over the summer and winter months and, as evidenced by the oak sinking to the bottom and the liquid changing from clear to very dark, there has been a lot of penetration into the oak.  I am going to start out with a 4 oz piece of oak this year and then, if I find more is needed, I have two additional oz that I can add.

Goose Island store their barrels in a non-climate controlled warehouse to approximate the aging conditions of the whiskey.  This should, in theory, drive the beer to be pushed and pulled out of the wood to the same depths the whiskey went and allow for more extraction of flavor.  Based on this I aged my beer in one of the hotter portions of the house and it did seem like the levels of flavor extraction improved as it got warmer out.  This year I'm going to try aging the beer up in the hot attic which I'm thinking should drive more penetration of the beer into the oak.

Like last year I'll be aging in a bucket fermenter.  I plan to use one with no airlock (will have a hard bung) to allow some pressure to build.  This will run some risk of bursting the bucket so I'll be sure to check on it regularly to assess the pressure situation - will vent off some pressure if necessary.

The recipe this year is just about the same as last time as the base beer was very nice.  The only difference this time is that I'm using black patent, which was specified in the Goose Island recipe, rather than debittered-black malt specified by somebody else's clone recipe.  I'm thinking this could have been a contributor to the sharper flavor of the original.

I'll also be mashing a bit lower this time to get the beer to finish closer to the target 1.030 (mine finished at 1.036 last year with a 155 F mash.  Will shoot for 154 F this time.

Recipe Details:

• Grain:
• 24 lb 2 Row
• 8 lb Light Munich
• 1.5 lb Chocolate Malt
• 1.5 lb Crystal 60L
• 1.5 lb Roasted Barley
• 12 oz Black Patent
• 4 oz Acid Malt
• Hops:
• 1 oz Magnum (Pellet 11.8% AA) at 60 min
• 1 oz Summit (Pellet 17.1 % AA) at 60 min
• Yeast:
• 2 Packs of US-05 "Chico" Ale Yeast (2nd Pitch for one pack)
• Water:
• 20 gal Spring Water
• 2 gal Tap Water
• 2 tsp CaCl
• 2 tsp Gypsum
• 1 tsp Irish Moss at 15 min

Process Details:

• Batch Size:
• 7 gal (Target 6 gal)
• Mash:
• 154 for 60 min (154 F for 60 min)
• Boil:
• 4 hrs and 45 min (Target 4 hrs)
• Fermentation Temperature:
• 68 F
• Primary Duration:
• 1 Month
• Secondary Duration
• 6-8 Months

Results:

• OG:
• 1.136 (Target 1.130)
• Efficiency:
• 7.2 (Target 58%)
• FG:
• 1.055 (Target 1.030)
• Apparent Attenuation:
• 57% (Target 67%)
• ABV:
• 12.81% (Target 13.73%)

Brewing Notes:

• 3/9/19 - Brewday - 9:45 AM to 6:30 PM - Including setup and cleanup
• Brought 7 gal of spring water and 2 gal of tap water up to 190 F
• Milled half the grain for the first mash.  Added half the CaCl and Gypsum to the mash

• Added 7 gal of water to the mash tun
• Cycled this through the Grant and RIMS until the system had normalized to 165 F
• Added the grain - stirred well to eliminate dough balls
• Cycled with the RIMS and mashed for 60 min - the temperature was 154 F for most of the mash
• Added 5 more gal of spring water to the HLT for the sparge and heated this up to 190 F
• Slowly drained the mast tun into the boil kettle.  Added water to the top of the mash as I went.  Sparged until I ended up with 8.5 gal in the boil kettle
• I started heating the boil kettle after collecting 3 gal.  Had it to a boil shortly after the sparge completed
• Boiled for 2 hrs
• There was a lot of hot break for the first 30 min.  I had a few minor boil overs.  I had adjust the heat throughout to limit this

• I saved off the remaining wort from the mash tun for use in the next mash (had about 2 gal)
• Heated 7 gal of water in the HLT for the next strike.  Let this get up to 170 F
• Milled the second half of the grain.  Added the other half of CaCl and Gypsum to the milled grain.
• With about an hr and 10 min left in the boil I transferred water and the extra wort from the previous mash to the mash tun until I had 6 gal.  I cycled this through the RIMS for 10 min.  The temperature fell to 149 F.  I cycled for 15 more min with the RIMS set to 170 F.
• I slowly added the grain with the RIMS running over the 15 min extra cycle and it slowly crept up to 153 F.
• Mashed for 60 min - the temperature got up to 156 F with 30 min left
• Heated 5 gal of sparge water up to 190 F
• At the end of the 2 hr boil I had about 3 gal of beer.  Measured the gravity as being above the 32 brix limit
• Sparged the second mash until I had 11 gal in the boil kettle

• Started heating after I had 4 gal.  Had it to a boil prior to the end of the sparge
• Boiled for 2 more hrs
• Added hops with 1 hr left
• Measured the gravity at 50 min at 29 brix.  I probably have about 8 gal.  My target is about 30 brix so I think I'll be a bit higher than target at the end of the boil.  I will top up with spring water if necessary.
• I've been unable to run the burner at full flame due to the large amount of hot break that builds threatening boil overs.  This slowed the boil off rate.  Had about 7 gal of beer at the end of the 4 hr boil.  Decided to extend it by 30 min.
• Added Irish Moss with 15 min left
• Put in the wort chiller to sanitize with 5 min left
• At the end of the boil I chilled the beer down to 75 F
• Rehydrated two packets of US-05 in 100 F spring water for about an hr

• Transferred the beer into two fermenters.  I split it so there were 3 gal in each.  Let it drop a foot or so to aerate.  Pitched the yeast during the transfer.

• Measured the gravity with my hydrometer as being 1.170.  I was shooting for 1.130 so I majorly overshot.  I need to add 1.5 gal to the beer to get to 1.135.  
• Added 1 gal of tap water split between the two and checked with my refractometer.  Measured the beers as 31 and 32 brix after.  This is 1.138 and 1.134.  I think this is close enough - I'm going to skip the extra half gal.
• Moved the fermenters into my fermentation chamber with a reptile heating pad.  This should hopefully keep it at the desired 68 F.  I'll allow it to ramp up after a few days.
• 3/10/19 - The airlock was bubbling lightly by this evening
• 3/17/19 - Airlock activity has faded to almost nothing.  Will give this another week and then combine the two batches,
• 3/22/19 - Checked on the beer.  The krausen has fallen and there are some bubble come up from the bottom.  May still be wrapping up
• 3/29/19 - Combined the two beers into the stainless fermenter.  Transferred using an auto-siphon.  The beer is almost to the top of the fermenter.  Moved this out of the chest freezer and into the mid-60's basement to finish up.

• 4/24/19 - Moved the beer to my chest freezer to cold crash at 38 F
• 4/28/19 - Added half a tsp of gelatin dissolved in hot water to drop any remaining yeast
• 4/28/19 - Transferred the beer into a bucket fermenter with the 4 oz of charred oak.  I ended up with about 5.5 gal of beer in secondary.  I measured the gravity of the beer as 1.064 so we're quite a bit above the target of 1.040.  Moved the bucket fermenter up to the hot attic to age for the next 6 months or so.  The fermenter has no airlock or bung so pressure will build up in there.

• 8/3/2019 - Took a sample after about 3 months aging with oak up in my hot attic and compared with 2017 BCBS.  Mine is thicker and maltier than the real thing.  The beer has a nice whiskey character but the BCBS has a much firmer spirit presence.  I have 4 oz of oak in the beer at the moment.  I'm going to add 2 more oz of charred and whiskey soaked oak for the remaining 3-4 months of aging

• 11/28/19 - Measured the gravity as 1.055.  It has a really lovely dark chocolate and roasted flavor.  Whiskey and oak are present but in the background.  Its pretty sweet still.  Sampled the beer next to BCBS 2017 and found mine to have a lot less of an alcohol presence like last year.  I'm considering adding a bit of the barrel proof spirit I've been using to age the oak with to the beer at bottling.  Assessed the impact of adding small amounts to a quarter cup of the beer.  It seemed like something close to 1/2 tsp of the 60% barrel aged spirit per 1/4 cup of beer was needed to get my beer close to the level of boozyness that BCBS achieves.  I have about 6 gal of beer.  At 1/2 tsp per 1/4 cup this would require the addition of 4 cups of the spirit (This is 96 cups or 384 1/4 cups in 6 gal which would be 384 1/2 tsp or 192 tsp).  My homemade whiskey is quite a bit more oaky than a commercial version.  Used at the 4 cup per 6 gal level the oak is very prominent.  I think I may back off to 3 cups per 6 gal which doesn't match to alcohol presence (but still gets close) and makes a better balance between beer and oak.

• 12/8/19 - Bottled the beer today with 4 oz of priming sugar, 1 package of Red Star Premier Cuvee Champagne yeast, and 3 cups of 60% alcohol I aged with oak (I watered this down with about 2/3 Everclear and water mix to reduce the oak flavor.  Ended up with almost 6 gal which netted me 42 15 oz bottles
• 8/9/20 - Tasting Notes - A really rich and boldly flavored beer with a broad array of flavors which bring a nice complexity.  Really nice sipping beer.  Judged on its own merits, it's a really nice beer.  I believe the whiskey character is a bit too far in the background to bare much resemblance to BCBS (will explore that further in a direct vertical tasting soon).  Still happy to drink this beer and not unhappy that I may have missed the mark a bit.
• 9/6/20 - Vertical tasting comparing this to the real BCBS performed.  This beer, though delicious, is much more malty than the real thing and is far off in terms of whiskey character.

Lessons Learned:

1. Getting down to the target 1.030 gravity is important if your aim is to clone this beer.  I will consider using high gravity yeast for the next version
2. The 60% alcohol mix I'm using to age the oak is much more heavily oaked than a 55 gal barrel of whiskey is.  As a result, my whiskey is a lot oakier than regular whiskey.  I may want to adjust the amount of oak I'm using in a quart jar.  I've tried this whiskey (watered down to 45%) next to Makers Mark in an Old Fashioned and both my wife and I thought it was at least as good if not a bit better (more flavorful).  So, if I ended up reducing the oak to spirit ratio it isn't like the extra spirit would end up dumped.
3. I toasted this oak at 450 F.  I may want to adjust this down to 400 F to get more vanilla next time.