What is Peated Whiskey? Everything you need to know.

18/11/2020
Updated: 24/12/2020
4 mins read
What is Peated Whiskey? Everything you need to know.

Peating is an incredibly decisive factor for connoisseurs and purveyors of Scotch. Some people love it; others do not. It is something that once you begin to drink Scotch regularly, you will be able to tell straight away whether the process has taken place.

But what is peating? Let's take a look!

What is peated whiskey?

Peated whiskey has a very distinctive flavor, think deep, smokey, almost like a campfire or barbecue type flavor.

Peated whiskey is given the taste by the compounds that are released by the peat fires that are used to dry the malted barley. How long the malted barley is exposed to the smoke created by the peat is the determining factor as to the intensity of the smokiness and flavor, rather than the actual peat itself. 

What is the history behind peated whiskey?

For a very long time, peat was the most readily available fuel in Scotland. The accumulation of water in boggy areas slows down the decomposition of plant material such as grass and tree roots, leading to peat creation.

Peated whiskey barrels

Peat is generally considered to be a fossil fuel because it accumulates so slowly and some bogs are between 1000 and 5000 years old. The layers of peat can be up to three meters deep. When you consider that peat accumulates around 1mm a year, a three-meter deep peat bog is 3000 years old. 

The peat is cut into small slices and built up into small pyramids to dry out. The water drains off the peat very quickly and turns the delicate pieces into hard briquettes. Like coal, the peat briquettes contain the dead plants’ energy, making them an excellent form of fossil fuel.

Because it was so readily available, peat was the primary domestic fuel in Scotland for a long time, fuelling kilns in distilleries as well as household hearths.

How was peating used?

Nowadays, when producing Scotch whiskey, distilleries generally use barley that has been malted commercially.

However, they would have had to do this essential part of the process themselves in the past. Malting makes the starches in the barley soluble, allowing the sugars to be turned into alcohol. It speeds up the process of germination, then halts it in the kiln.

Peated whiskey glasses with cigar

To heat the kilns, peat was used. Peat produces distinctly aromatic smoke when burned. This significantly influences the malted barley, tainting it with compounds known as 'phenols.’

Some of the most common flavors given off by peating are smoke, ash, iodine, and tar. These all create an intensely deep flavor for the Scotch whiskey.

Why have many distilleries stopped using peat?

As mentioned above, peat was the most readily available and accessible fuel, therefore at the very core of the Scotch whiskey industry.

It was particularly important for the distillers located in the Highlands and islands, which were very remote and cut off from the rest of the country. 

Peated whiskey on glass

When coal, and after that coke, became an alternative to the heavily aromatic peat, many distilleries converted. 

As rail transport links in Scotland began to develop and become more accessible, coke became even more popular with distilleries. Coke is much more even and consistent with burning and created less smoke, which is what swayed many Scotch whiskey producers.

Did all distilleries move away from peat in the malting process?

Many distilleries shunned the trend of moving to coal and then coke and decided to stay with peat. This was mostly dependent on the location of the distillery. Many had little choice. Orkney, in the north of Scotland, Islay in the west, and some of the mainland distilleries were the ones that clung on to the peating tradition. Even now, these distilleries use differing amounts of peat in their Scotch whiskey production, which gives it a unique and very distinctive smoky flavor, which as we mentioned above, divides opinion amongst Scotch whiskey experts. 

How is the level of peat in Scotch whiskey measured?

Generally, the 'peatiness' of Scotch whiskies are measured in the phenol parts per million or the PPM. This alludes to the quantity of the phenols in the malt used rather than the phenols in the finished Scotch whiskey.

Some of the lighter Scotch whiskies measure in at around 20 phenol parts per million. 

Peated whiskey on glasses

At the very other ends of the scale, there are ones from Bruichladdich with peatiness levels reaching 300 PPM. However, it is not an exact science, and even those Scotch whiskies with similar levels of peatiness can taste very different from one another. 

Can a distillery control the levels of peatiness in their Scotch whiskey?

The degree of peatiness of a whisky is dictated by the amount of time the barley grain is exposed during the drying progress to the intense peat smoke. Damp malt normally takes approximately 30 hours to dry, but of course, distilleries can choose to keep it in the peated kiln for longer for that distinctive smoky flavor if they so wish.

Why do different areas produce different flavored peat?

Each peat bog has a distinct chemical signature and bestows a specific profile of flavor and aroma. The characteristics of the peak aroma are influenced by variations in vegetative composition and the prevailing climate.

In Islay, for example - a coastal area - the peat possesses an iodine type aroma, one that smells not all dissimilar to oily fish.

Peated whiskey on table

In Eastern Scotland, where the climate is a lot drier, there is less moss, so the flavor is much less medicinal and drier and colder.

In Orkney, the peat is dominated by decomposed heather, adding a floral flavor to the pear, and therefore to the Scotch whiskey that is produced there.

Opt for a youthful Scotch whiskey if you want a powerful blast of flavor, while if you want those medicinal flavors to be more subtle but still perceptible, opt for an older whiskey.

By Ashleigh Cain

Ashleigh is a key part of the editorial team at Whiskey Rocks. You'll often find her either writing educational articles or reviewing the latest artisan whiskeys. Her favorite drink? Ashleigh loves smokey scotches like Laphroaig, but you'll also often find her with an old fashioned in hand.

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