Peat is decayed organic material that has been compacted over thousands of years. With peat bogs prominent throughout Scotland, peat has long been used as fuel and has provided a natural source of heat in the whisky industry. Here, it is sliced and dried into briquettes, which burn at a consistently high temperature. It is the burning of peat underneath the malted barley as it dries that imparts the grain with that unmistakable smokiness – the longer the exposure to the smoke, the greater the intensity of peaty flavour.
Into the Smoke
Of course, there’s no painting the quality of smoke with one broad brushstroke. There are varying types of smokiness due to the different processes, shapes of stills and various techniques that contribute to the final taste profile. There’s also something to be said for regional influences and natural elements such as the salt spray from the sea that can add more pronounced characteristics to the whisky, highlighting different shades of the peat.
On the Scale
The whisky industry has developed a scale to help admirers zero in on their preferred intensity of smoke. Peat smoke contains chemicals called phenols, and once the malt has been dried and taken away for mashing, the phenol count is measured in phenol parts per million (PPM). That number indicates what level of peaty flavour to expect – Bruichladdich ranks at 3-4 PPM, Highland Park at 20 PPM, Lagavulin at 35-40 PPM and Ardbeg at 55 PPM. Take your lead from that, but the best way to judge different flavours and distinguish the nuances that each distillery delivers remains side-by-side tastings.
For those intrigued by the region that delivers the peatiest punch, look no further than Islay. This is ground zero for peaty whiskies, and Islay has long staked its reputation on these distinctive flavours to attract a fervent following. In addition to Ardbeg, this is where a number of prominent brands, such as Laphroaig, Bowmore, Lagavulin and many more operate. Again, upon closer inspection, it is remarkable the varying shades of smokiness that each distillery produces.