October 22, 2016: Imperial Porter

We have returned to our Vanilla Bourbon Imperial Porter recipe that we enjoyed in California. We are looking forward to this beer and hope we aren’t disappointed.

Grain bill:

• All grains were purchased at Hops and Berries in Fort Collins, CO.
• 12 lbs 2 row domestic
• 2.75 lbs Munich 15L
• 1.5 lbs Brown Malt
• 1.5 lbs Chocolate Malt
• 1 lb Crystal 120L
• 1 lb Crystal 60L

Hops (Pellet):

• 0.375 oz Northern Brewer 7.3% alpha acids
• 0.875 oz Chinook 11.9% alpha acids

Yeast:

• Wyeast 1272 American Ale II (#1005271, mfg 9/27/2016)

Stats:

• Starting gravity: 1.080
• Brewhouse efficiency: 85%
• Final gravity: 1.015
• Approximate %ABV: 8.316
• Approximate IBUs: 39 (Rager)/27 (Tinseth)/38(Daniels) as determined using the Hopsteiner and Homebrewing.com IBU calculators.

Water:

• The city of Loveland has great water. We will pass the water through an activated charcoal filter to remove any chlorine that may be present.

Procedure: Yeast was propagated in 1.2 L of media (1:10 DME:water) in a 2L flask with stir bar that had been sanitized with Star-San. Media was inoculated from Wyeast Smack Pack. Propagation culture was grown at room temperature with stirring for 16 hours.

Strike temperature was 78 degrees Celsius. A ~2.5:1 water to grist ratio (L:kg) was achieved with 22 liters of water. Mash in temperature was 69 degrees Celsius, 1 degree above target. The mash was fly sparged at 74 degree Celsius until the volume of sweet wort in the boil kettle was approximately 10 gallons. Hydrometer reading of the last wort remaining in the mash tun was 4.0 Brix.

Sweet wort was brought to a vigorous boil and boiled for 90 minutes. All hop addition times are listed as time remaining in the boil. Chinook – 60 minutes; Northern brewer, 1 tablet Whirlfloc – 10 minutes. After whirlpooling and allowing the trub to settle, the hopped wort was cooled to 19 degrees Celsius with a counter-flow plate chiller with a recirculating ice/water slurry. The hopped wort was oxygenated. The yeast starter culture was immediately pitched into hopped wort.  The fermenter was placed in an incubator with temperature monitoring only, until 22 degrees Celsius  was reached. Temperature control was then set in cooling mode, with 20 degrees Celsius being the maximum temperature.

After a week in the primary fermenter (Spiedel), the beer was transferred to a metal conical bottom fermenter with 5 oz vanilla beans, split and chopped. During fermentation, diacetyl character was noted at time points 28 to 51 hours, but was not present afterwards. The fermenter was kept at ambient temperature (19 Celsius) and was then cold crashed. The beer will be transferred to a keg, where bourbon will be added.

Comments:

• The shorter propagation time resulted in a beautiful profile. Happy, healthy yeast make great beers! We are definitely staying with a shorter propagation time.
• We are now tracking temperature. More data!
• Our brewhouse efficiency was a whopping 85%. Looking forward to trying to replicate this efficiency.
• Our boil was not as vigorous as desired, resulting in a larger fermentation volume. We expect our original gravity would have been higher with a more vigorous boil (more evaporation, less volume, more concentrated sugars).