Tears of Chthulu Quad IPA

A few months ago my friend, fellow London Homebrewers Guild member, and occasional brewing pal Devin challenged me to a brew-off. In only one month I was to make the strongest beer that still tasted good. Not to be one to let a challenge pass me by, I began designing a strong IPA-inspired beer to win the day. I decided on a Quad IPA, as the simpler malt and yeast character lends themselves to quick-finishing beers, while the high hopping rate may cover up any fermentation flaws. But the key to this beer was making every effort at each stage of the brewing process to minimise the risk of off-flavours.

Continuing with this years Scifi theme, this Quad IPA is named after H. P. Lovecraft’s Cthulhu, a dread alien/god whose visage alone is enough to drive a man mad. I figured if such a beast exists, its tears would be something like this beer…bitter, bold, and potentially fusel-filled!

They were not composed altogether of flesh and blood. They had shape […] but that shape was not made of matter. When the stars were right, They could plunge from world to world through the sky; but when the stars were wrong, They could not live. But although They no longer lived, They would never really die. They all lay in stone houses in Their great city of R’lyeh, preserved by the spells of mighty Cthulhu for a glorious resurrection when the stars and the earth might once more be ready for Them. 

Lovecraft, “The Call of Cthulhu“

Managing Yeast – the Main Approach to this Quad IPA

My approach to this brewing Quad IPA was all about minimising off-flavours, while also trying to promote the complete fermentation of a very high gravity beer. I chose a method that deviates significantly from my tried-and-true method – adding sugar mid-fermentation, and pitching additional yeast after high kraussen passes. I hoped – perhaps naively – that careful up-front yeast management would be sufficient. My approach here was multi-fold. Firstly, I picked a strain known for fermenting high gravities with minimal off-flavour production (White Labs WLP099 – Super-High Gravity). This yeast can produce a vinous character at higher alcohol levels, so I aimed for a gravity at the lower end of where this character begins to appear (still ~16% ABV).

Secondly, I minimised oxygen-related off-flavour production by performing the entire fermentation process in a single sealed container – i.e. in a keg. This protected the beer from oxygen throughout fermentation, thus limiting off-flavours and preserving hop aromatics. This also offered a good temperature control opportunity, as I could easily keep the keg at the desired temperature with a brew-belt and my cold (14C/57F) basement.

It was critical that I carefully control the ferment to minimise off-flavours. Most off-flavours, or their precursors, are formed during yeast growth. So I minimised yeast growth through preparation of a large amount of yeast and careful control over the fermentation environment. I aimed for – and slightly exceeded – a pitch rate of 1.75 million/ml/degree plato. Yeast numbers and health were maximised by adding a large dose of yeast nutrient and peptone to the starter. I timed the starter to ensure it would complete sedimentation right on time to be pitched into the beer, to limit any issues with ageing yeast.

During the ferment I carefully controlled the fermentation temperature to further minimise off-flavour production. This meant pitching at 18C (64F); slightly below the minimum suggested temperature for the yeast. This lower temperature was held for 3 days, during which time I gently shook the keg every 8-12 hours. This is a trick from mead making reduces stress on yeast by forcing dissolved CO2 out of solution. Each time I did this I got massive foaming in the blow-off container, showing that I was achieving that goal.

Fermentation had mostly subsided by the 48 hour mark, so I warmed the beer to the mid-range temperature of the yeast (18.8C/66F) to ensure continued fermentation and cleanup of off-flavours. This warmer temperature was held until the end of the second week of fermentation, at which point I dry-hopped. To dry hop, I sanitised a hop bag in boiling water, placed the hops in the bag, and suspended the bag in the beer using fishing line. I dry-hoped for 5 days, at which point I used the fishing line to raise the hops out of the beer, and let them “drip dry” for 24 hours. I then removed the hops from the keg, and kept the beer at 18.8C for one final day…bringing the beer up to day 21 of the 28-day brew schedule.

The last step was to cold-age for the final week. I disconnected the blowoff tube from the keg and moved the keg to my keezer. I purged the keg two times with CO2 and force-carbonated for 24 hrs at 25 PSI. The beer was then returned to serving pressure for 6 days before bottling. It was exactly 4 weeks from  brewday to the day I bottled this Quad IPA. Brewing challenge completed…but was the beer any good?

The Recipe – Tears of Chthulu Quad IPA

For such a strong beer, the recipe is quite simple. A simple malt bill plus a bunch of sugar gives the desired 1.130 to 1.150 gravity. I only brewed 5 litres (just over 1 gallon) of beer, but I loaded it with 112g (~4 oz) of hops. A healthy bittering charge plus hefty whirlpool and dry-hop additions should provide enough hop character to hide minor fermentation defects. At any rate, 136 IBU’s of bitterness of Quad IPA awesomeness should bring a tear or two to Chthulu’s eye.

Malts (for 5L of beer):

• 1.5 kg of Canadian 2-row malt
• 70 g of Crystal 40L
• 0.5 kg beet or cane sugar (added last 5 min of boil)

Mash:

Stove-top brew-in-a-bag:

• Added 8.25L of water, mashed at 68.9C (156F) for 60 min. 1/2 tsp gypsum and 0.5ml of lactic acid added as a water adjustment
• Mash-out with direct-heat, 75.6C for 10 min

Hops (for 5L of beer):

• Warrior, 16%: 10g, 60 min in boil, 14g as 5 day dry-hop
• Centennial, 7.8%: 14g 25 min whirlpool, 14g 5 day dry-hop
• Columbus, 14.5%: 14g 25 min whirlpool, 14g 5 day dry-hop
• Simco (13.6%): 14g 25 min whirlpool, 14g 5 day dry-hop

Brewing Process:

I boiled the wort for an hour, adding whirflock and 0.5 kg of sugar in last 5 minutes. The worts gravity was high (~1.180 SG), so I added ~400 ml of water to adjust to 1.138. I let the beer cool for 5 min to ~80C (180F) and added whirlpool hops for 25 minutes.

I chilled the wort by placing the pot in a sink of ice water. While the beer was cooling I sanitised the brew-in-a-bag bag by boiling it in water, and then placed it into the neck of a sanitised keg. Once cooled, I poured the wort into the keg, using the BIAB-bag as a filter. Using a sanitised spoon, I pressed the residual wort out of the mass of hops and trub, and then moved the keg to the basement.

The beer sat for about an hour, to ensure it had equalised to my desired pitching temperature of 18.4C. I then oxygenated the wort by shaking the keg for a few minutes. I didn’t want to add too much oxygen, as the goal is to minimise yeast growth. Hence, my reliance on a huge pitch rate, rather than more rigorously oxygenating the wort. I then carefully  decanted the yeast, leaving just enough media to suspend the yeast. I pitched the yeast, added a blow-off tube, and set the temperature – and the Quad IPA quickly began to ferment! The remainder of the brewing process is described above, so I won’t repeat it here.

Stats:

• OG: 1.138
• FG: 1.011 (refractometer + correction), more likely 1.020-ish (taste)
• ABV: 17.4% (refractometer), 16% (probable)
• IBU: 136 (calculated)
• SRM: 7
• Hop rate: 22.5 g/L (3 oz/gallon)

The Ferment

I already discussed my approach to fermenting this Quad IPA above, but the one thing that amazed me was its speed. Within ~48 hours the bubbling of the blow-off had slowed to a crawl. This beer has the highest pitch rate of any beer I’ve brewed previously, which may explain the quick finish. But even with the  quick fermentation, I took full advantage of the time period for this challenge to ensure fermentation finished, and to give the yeast a chance to clean up any off-flavours.

Tasting Notes – Tears of Chthulu “Quad” IPA

Appearance: Light brown with a fair amount of haze. The beer’s head is short-lived.

Aroma: Very strong American hop character, slight alcohol note.

Flavour: Fairly sweet, which combined with the high hop bitterness, ends up with a somewhat neutral balance – not the bitter hop bomb I was hoping for. A strong hop flavour adds a citrus note, although not as bold as I had hoped – again, likely due to the higher level of residual sugar. Aftertaste is neutral – a bit of sweetness, a bit of hop bittnerness.

Mouthfeel: Medium bodied, with a slight alcoholic burn in the aftertaste.

Overall: Not quite what I was hoping for – still very strong, but the bitter/sweet balance is off, leaving the beer overly malty and lacking the substantial bitter punch I was hoping for.