Barrel-aged imperial stouts are the crown jewels of the beer world. These complex, high-alcohol brews are packed with vanilla, dark fruit, chocolate, and coffee flavours. Let's dive into the art of crafting these majestic brews.
Recipe Construction: Building the Foundation
Malts: The Heart of the Beast. The key to a great imperial stout lies in its malt bill. While it's tempting to throw in every speciality malt under the sun, focus on a few key players:
- English base malt (Maris Otter or Golden Promise) 50-60%
- Toasted malt (Munich, Munich II, Victory) 10-20%
- Crystal/caramel malts 5-10%
- Chocolate malt 3-5%
- Roasted barley or black malt 3-5%
With this guideline, we are trying to layer the flavour for complexity using as few malts as possible. The English base malts add a malty, nutty flavour, and the toasted malts add a toasty biscuit flavour. The crystal/caramel malts add caramel, toffee and some dark fruit flavours, and the chocolate and black malts add chocolate, coffee and roast character.
Many people add malted and unmalted adjunct malts like wheat and oats, which can help add more body and mouthfeel. Lactose is historically uncommon in this style because the final gravity is usually high enough to balance the alcohol and bitterness from the dark malts and hops. But recently, lactose has become more common to be added with more pastry imperial stouts.
Hops: Subtle Support. Hops play a supporting role in imperial stouts. Usually, a relatively neutral high alpha varietal is selected, like magnum or green bullet. These are added in a single 60-minute addition targeting 30-50 IBUs.
Yeast: The Unsung Hero. Choose a yeast strain able to handle high-alcohol environments. American strains tend to be more neutral, whereas English strains tend to add more fruity notes but may not ferment out completely. Pitch at a rate of 1 million cells per millilitre of wort per degree Plato or 2-3 packs per 23L.
Mashing: The Crucial First Step
Higher mash temps can compensate for the thinning effect of fermentable adjuncts. Typically, most brewers will do a single infusion mash at 66-69°C for 60 minutes.
Fermentation: Where the Magic Happens
Healthy Yeast Pitch: Estimate your pitch rate based on:
- Wort concentration (gravity points)
- Ale or lager yeast
- Batch size
Oxygenation: Fuel for Your Yeast. Proper oxygenation is crucial for yeast health. Aim for 8-10 ppm dissolved oxygen in the wort before fermentation.
Nutrients: A small nutrient addition is an excellent way to ensure the yeast fully ferment out.
Barrel Ageing: The Final Touch
Wood Selection Choose from:
- American Oak: Sweeter, with more vanilla notes
- French Oak: Subtler flavours, silkier tannins
- Spanish Cedar: Woody aroma with citrus and spice notes
Often, these woods will also have an associated toast/char level, which adds toastiness, caramel, charcoal and vanilla flavours.
- Untoasted
- Medium Toast
- Heavy Toast
- Light Char
- Medium Char
- Heavy Char
Pre-used barrels can impart flavours from their previous contents like barrel-aged wine, whisky and bourbon. These are great for adding complexity to the final beer, but they can also add extra alcohol, which is something to keep in mind.
There are several Barrel formats:
- Chips
- Cubes
- Spirals
- Staves
- Barrels
View our range of barrel ageing products here.
How to age:
Woods are porous, which means they are very good at harbouring microorganisms. Most barrel-aged imperial stouts are clean beers. This means the woods need to be sanitised first. This can be done with boiling hot water or with high alcohol percentage spirits.
Steep the wood or fill the barrel with either hot water or spirits. For the hot water, leave for about 10 minutes; for the spirits, leave for at least a day or two.
The wood can then be added to the fermenter at fermentation temperature, or the barrel filled with the beer. Due to the surface area of the wood, most home brewers will age the beer for up to 6 months on the wood. Age your imperial stout until the oak flavour is slightly stronger than desired, then transfer to a keg for further ageing under cellar conditions.
Crafting a barrel-aged imperial stout is a labour of love that requires patience and attention to detail. But when done right, the result is a genuinely magnificent brew that's well worth the wait.
MYO Drinks
Helping you to make your own Great Batch from Scratch.