Beware the allure of Scotland’s iconic style of whisky. Peated whisky is polarising. Some love it, some hate it, but very few people are impartial to it.
My first experience of peated whisky made me recoil in horror, as many do first time round. My brain couldn’t get past the trichlorophenol (think TCP mouthwash). But as with most things, fear of the unfamiliar subsides and is gradually replaced with something else, beware, all of a sudden, a whole world of flavour opens up.
Now I’m a peat lover, a smoke-head. I enjoy reading the tasting notes of leading whisky writers and critics of their favourite peated drams. The notes are often long, they are often nostalgic, sometimes comical, sometimes downright absurd sounding. But the energy of the experience is usually laid down on paper, and the drinker is left thoroughly satisfied.
Just how did we come to drink such a powerful smoky dram, infused with unusual flavours of tar, iodine, smoke, marine and medicinal notes?
Peat is decomposed organic matter that has been trapped in the ground for thousands of years and is essentially young coal. In Scotland, for a long time the most ready source of fuel was dried peat, which was cut from peat bogs with shovels, and dried in brick-like forms. Peat was mostly usurped in the home by coal, by the 1950s.
For the origin of peat smoked barley, the answer really lay in the need to extract sugars from grain. Yeast can’t metabolise (ferment) the complex starches in a grain like barley. These first need to be broken down into simpler sugars with the help of enzymes, the job of the brewer. It is malting the barley (germinating then killing the seed) that produces the enzymes in the grain that brewers need for this sugar breakdown and extraction. In the past, most distilleries needed to malt their own barley as there were few dedicated commercial malting plants. A key part of malting is to kill the grain immediately after germination by heating it in a kiln. You guessed it, this kiln was fired by peat, and this smoke would infuse the barley malt with its rather particular and complex smoke profile, and thus peated whisky was born.
Nowadays whether distilleries malt their own barley or not, they have the option to continue to smoke the malt using peat to develop these traditional flavours. A lot of the signature flavour comes from a group of compounds called phenols that are infused into the malt. Peated whiskies are generally compared using a measure of phenol parts per million (PPM). This refers to the quantity of phenols in the malt itself rather than the contents of the finished whisky. Some lighter peated whiskies might measure up to 20ppm. Typically, a measure of 50ppm indicates a fairly heavily peated malt, and by association whisky. This measure is a fairaly blunt tool, however, as phenols are just one component of the flavour profile, and production methods vary between distilleries, meaning whiskies of similar ppm can taste quite different from one another.
Peated whisky remains a defining aspect of Scotch whisky, and its allure has caught on with single malt producers in other regions like Japan and India.