Two Grains, One Great Beer

Roasted barley is the soul of a stout. Unmalted, roasted hard until it turns near-black, it delivers the dry, coffee-like bite that separates a stout from a sweeter porter. Flaked oats are its opposite in almost every way: pale, soft and rich in beta-glucan, they bring body and a silky, almost oily mouthfeel that rounds off the roast's sharp edges. Put the two together and you get a beer that tastes dark and assertive without turning harsh — bitter chocolate, espresso, a whisper of porridge.

It is one of the most forgiving styles a home brewer can attempt, and one of the most rewarding. The recipe below makes 19 litres and suits a cool box mash tun, a dedicated mash tun or a brew-in-a-bag setup. Expect an original gravity around 1.052 and a final gravity near 1.014.

The Grain Bill

• 3.4 kg pale ale malt — the base, and the source of the enzymes that will convert the oats.
• 600 g flaked oats — plain porridge oats from the shop work perfectly well.
• 400 g roasted barley — your coffee and dark-chocolate character. Start here and adjust next time.
• 250 g chocolate malt — cocoa, plus a little extra colour depth.
• 200 g medium crystal malt — a touch of caramel so the finish doesn't feel thin.
• 150 g rice hulls — optional, but cheap insurance against a stuck sparge.

That works out at roughly 70% pale malt, 12% oats and 8% roasted barley, with the rest made up of speciality grains. Want more body? Push the oats to 800 g. Want more bite? Add roasted barley 50 g at a time — its influence grows quickly.

Mashing: Taming the Oats

Oats absorb water and beta-glucan like a sponge, turning a thin mash into something closer to wallpaper paste. Two habits will keep you out of trouble. First, use a generous liquor-to-grist ratio — around 3 litres per kilogram — and stir thoroughly to smash any dough balls. Second, add the rice hulls and open your mash tun's tap slowly. If you brew in a bag, use a coarser crush and lift the bag gently rather than squeezing it.

Mash at 66-67°C for 60 minutes. That range favours body over fermentability, which is exactly what a stout wants. Check your mash pH and aim for 5.4-5.5; dark malts drag it downwards, so if your water is very soft you may need a little bicarbonate of soda to lift it. Sparge with water no hotter than 76°C to avoid pulling harsh tannins out of the roast.

If your previous stouts tasted ashy, try cold steeping the roasted barley instead. Steep it in 2 litres of cold water overnight, strain, and add the liquid to the boil. You lose a little colour and bitterness, but the roast character turns smooth and cocoa-like.

Boil, Hops and Yeast

Stout is not a hop showcase, which is a blessing for the less experienced brewer. Aim for 30-35 IBU, mostly from a single bittering addition.

• 60 minutes: 45 g East Kent Goldings or Fuggles (roughly 5% alpha acid)
• 15 minutes: 15 g of the same hops for a little earthy depth, if you fancy it

Boil for 60 minutes, adding a kettle fining at 15 minutes if you use one. Chill to 18-19°C and pitch a healthy dose of a robust English ale yeast — look for a strain described as high-attenuating and flocculent. Expect a vigorous fermentation and a thick, rocky krausen that will try to climb out of the fermenter, so leave plenty of headspace.

Fermentation and Conditioning

Hold the beer at 18-20°C for the first four days, then let it rise to 21-22°C for another three to clean up diacetyl and any residual sulphur. A dark, roasty wort can mask off-flavours, so don't be tempted to rush it. Once the gravity is stable across two readings — usually around day ten — it is ready to package.

Bottle or keg with 2.0-2.2 volumes of CO2. Stout wants gentle carbonation; too much fizz strips away the creamy texture the oats worked so hard to build. Condition for at least three weeks at cellar temperature, and if you can bear it, leave it six. The roast softens, the oats round out, and the chocolate notes step forward.

Serving and Tweaking Your Stout

Serve at 10-12°C in a straight-sided glass, poured without fuss. You are looking for a deep brown-black beer with a tan head that lingers, a nose of coffee and dark chocolate, and a dry, moreish finish that invites another sip.

Once the base recipe is reliable, the variations are endless. Add lactose for a milk stout, or cacao nibs and vanilla in secondary for a dessert edge. Swap 5% of the base malt for smoked malt if you want a restrained nod to the historical London style. Above all, keep notes on your roasted barley percentage — that single number will shape your stout more than any other decision you make.