Peated malt in beer and why brewers use so little of it

What peated malt is

Peat is partly decayed plant matter dug from bogs in Scotland and other cool, wet places. When maltsters dry, or kiln, green malt over a peat fire, the smoke deposits phenolic compounds on the grain. The result is malt that smells of smoke, earth, tar, iodine and seaweed. Distillers measure its strength in parts per million (ppm) of phenols.

Most of this malt is made for whisky. Our guide to peat and smoke in whisky explains how those phenols carry through distillation into the spirit.

Peat smoke versus wood smoke

Beer already has a smoked tradition, in Bamberg's rauchbier, made with malt dried over beechwood. Beech smoke is softer and closer to smoked ham or bacon. Brewers can use beech-smoked malt at a large share of the grist, sometimes most of it. Our guide to smoked beer and rauchbier covers that style.

Peat smoke is sharper and more medicinal. People describe it as antiseptic, sticking plaster or hospital floor cleaner at high levels. Those words are close to how brewers describe a phenolic fault, which is why the dose matters so much.

Why brewers use so little

Whisky goes through distillation, which removes much of the phenol. Long ageing then softens what is left. Beer has none of that. Every bit of phenol in the mash ends up in the glass, so peated malt hits far harder in beer than its whisky reputation suggests.

Most brewers keep peated malt to around 1% to 3% of the grist and treat 5% as a lot. In a 5 kg homebrew grist, that is 50 to 150 g. Peat level also varies widely between malts, so check the supplier's ppm figure and treat a heavily peated malt with extra caution.

Which beers suit it

Peat works best as a background note in strong, malty beers that can carry it:

• Wee heavy or Scotch ale, as a subtle smoky edge.
• Porter and stout, where roast and smoke play together.
• Old ales and strong dark beers aged on oak, chasing a whisky barrel feel.

One myth worth knowing: traditional Scottish ales were not made with peated malt. The smoky Scotch ale is a modern, mostly American interpretation. Judges in competitions often mark heavy peat down in Scottish styles.

Brewing with it

Mill and mash peated malt like any pale base malt. It has the diastatic power to convert itself. Keep the rest of the recipe simple so you can taste what the peat does. Ferment with a clean ale yeast, because yeasts that produce phenols of their own, such as hefeweizen or some Belgian strains, stack clove and spice on top of the smoke.

Start your first batch at about 1% and taste the finished beer before going higher. Smoke perception also fades a little with age, so a beer that seems slightly strong at packaging may settle after a few weeks.

A simple trial

If you want to find your own threshold before committing a whole batch, try a quick tasting trial. Steep a small handful of peated malt in hot water for twenty minutes, strain it and add measured drops of the liquid to glasses of a plain pale beer. You will quickly see how little it takes before the smoke turns medicinal. It is not exact, but it calibrates your palate better than any recipe note.

Write down what you used and what you tasted, then brew the full batch at a little below the level you liked. Smoke always seems stronger in a full glass than in a quick sip.

Peat, phenols and faults

Peat phenols are deliberate. Chlorophenols from chlorinated water, or phenols from wild yeast, are faults that also smell medicinal. If you brew a peated beer, make sure your water treatment and sanitation are solid so you know which is which. Tasters cannot easily separate a peat note from a chlorine fault in the same glass.

Getting it in India

Peated distilling malt comes in through malt importers, often in large sacks aimed at distilleries. Supply can be patchy. If you can only buy a big sack, remember you will use it at a few percent, so it will last a long time. Store it sealed and dry, because peat aroma fades in open air. Some suppliers also sell smoked brewing malts in smaller packs that are easier to start with.

Peat is one of many specialty malts with outsized effects. Understanding how specialty and roasted malts build flavour and colour is the foundation for recipe design.

Common questions

How much peated malt should I use in beer?

Usually 1% to 3% of the grist, rarely more than 5%. Peat phenols carry straight into beer without distillation to soften them.

Is peated malt the same as smoked malt?

No. Beech-smoked malt used in rauchbier is softer and can be used in large amounts. Peated malt is sharper and medicinal.

Are Scotch ales traditionally peated?

No. Traditional Scottish ales did not use peated malt. Peat in Scotch ale is a modern interpretation.

Can peated malt make beer taste medicinal?

Yes, if overused. At high levels peat smells antiseptic, which reads like a phenolic fault.