With Burns Night approaching, thoughts turn to whisky, and a peated dram is the favoured choice for many. But what is peat, and how does it get into whisky? Barbara Drew MW digs in to find out.

In the sometimes gloomy depths of winter, there are treats aplenty. Evenings spent close to the radiator, with a good book. Hot chocolate after a brisk walk in the cold air. And a smoky, iodine-tinged dram of peated whisky, at the end of the night. But what sets apart peated whiskies from their more common, unpeated counterparts? And how, exactly, are they made?

What is peat?

Peat is partly decomposed organic matter, formed in the damp, acidic conditions of bogs and fenland. It takes thousands of years to form, at the rate of just one millimetre per year. Because peat is organic though, it burns quite well and has been used for decades as a fuel source, when trees aren’t available.

It’s found in the aforementioned peat bogs, enormous areas of (often) wind-blasted heath, desolate and damp. It’s cut in the summer and laid out in bricks to dry. If you walk through the wilds of Scotland you’ll often come across such cuttings – some legal, some less so – in the summer months. A huge 20% of Scotland’s land area consists of peat bog.

How is it used in whisky?

Peat can be used in the malting process in whisky production (though it is optional). Once the barley has been malted (tricked into germinating with heat and water), the barley is then dried in a kiln. If this kiln is fuelled with peat, it adds a rich, smoky flavour to the malted barley. This smoky flavour follows the barley throughout the entire distillation process, eventually ending up in the finished whisky.

The intensity of the peat flavour varies depending on how much peat is used; and only a tiny amount is needed to leave its signature smoky kick. Peat level is measured in parts per million (ppm) of phenols, and even the smokiest whiskies may only have 50ppm – a tiny amount. Others may have just one or two ppm – just enough for a faint whisper of bonfire on the finish.

Scotland, and particularly the island of Islay, is often associated with peated whiskies. There is no monopoly on this style however; far from it. In fact when the Japanese whisky industry launched in the 1920s, modelled very closely on the Scotch industry, peat was just one of the many aspects borrowed from Scotland. Many classic Japanese whiskies now have the tiniest hint of peat to them, amongst them the Yamazaki.

As whisky production has expanded around the globe, peated (alongside unpeated) styles have taken off in regions as diverse as Sweden, Tasmania and India. Some new-wave US whiskies also use peat to add complexity and a smoky kick. But is all that about to change?

Sustainability

Due to how long it takes to form, peat is increasingly viewed as a finite resource. The truth is that anything is sustainable if it is used at a pace at which it can be replenished, and the amount of peat used in whisky production is slight indeed (and represents less than one percent of all peat use across all industries). Nevertheless, distilleries are increasingly looking to the protection and preservation of these landscapes as part of their overall sustainability approach.

In 2023, the Scotch Whisky Association launched its Commitment to Responsible Peat Use (CRPU) to promote responsible extraction, efficient use of peat during malting, and restoration of peatlands. With over 80% of Scotland’s peatlands degraded, the Scottish government has committed £250m to restore 250,000 hectares by 2030. And by creating the CRPU, the industry has taken its first collective step towards sustainable peatland management.

Of course, this is limited to Scotland for now and better control over third-party suppliers of peat is required. But this topic is moving up the agenda and distilleries around the world are now reviewing their peat use to ensure they are only using it when necessary, and maximising the peat they do use.

This doesn’t mean that your favourite smoky whisky is on the endangered list. But it does mean these products should be truly savoured; we’re unlikely to see the market flooded with a huge number of peaty styles in the future.

Three to try

Berry Bros. & Rudd Classic Islay, Single Malt Scotch Whisky (45.3%)

A great introduction to peaty flavours, this has a lovely gentle but persistent smokiness on the nose. The palate has a soft, creamy texture, with notes of orchard fruit and honey, offset by hints of kippers and iodine. A classic taste of Islay.

Westland, Peated, Single Malt Whiskey, USA (46%)

Peat is not just found in Scotch whisky and this bottle beautifully illustrates how this smoky flavour can enhance bottlings from around the world. This is a blend of five different types of malted barley, some unpeated and some which have been peated. The result is a balanced whiskey, with soot, orange peel and ginger alongside cocoa and spice flavours.

2013 Bruichladdich, Port Charlotte, Heavily Peated, PMC:01, Islay, Single Malt Scotch Whisky (54.5%)

This does what it says on the tin and is delightfully smoky and intense. Finished in Pomerol wine casks, there is a light red-fruit flavour underlying this whisky though. The Port Charlotte bottlings have plenty of peat flavour but are always beautifully balanced nonetheless. This is a treat for fans of a smokier dram.