Why Does Whisky Taste Like Smoke?

If you’re anything at all like me and enjoy sampling a variety of whisky from different regions of the world, then I’m sure you’ve encountered whisky with a varying degree of smoke within the flavour. Some regions are well known for producing smoky whisky which is often commonly known as peated whisky. This is not the only reason you might detect a smoky flavour in your dram though, so let’s dig in and uncover the main reasons your whiskies may taste of smoke.

Barrel Charring

In most cases, the inside of a barrel used in whisky maturation is toasted and charred. It is thought this was originally done to ensure the barrels were clean and to remove any leftover sediments from whatever may have been stored in the barrel previously, fish anyone? That may, or may not, be true and whether deliberate or not the charring has become an important part of the process in shaping the flavours of modern whisky.

Charring the barrel in preparation actually gets the wood into a better state ahead of maturation as the process is widely known to ‘open up’ the wood impacting the flavours and colour ultimately imparted to the spirit. Some of the most common flavours you’ll experience in whisky have passed directly from deep within the wood.

Although not that common, in certain instances you may taste a light smoke which is a consequence of the charring of the barrel.

What is peated whisky?

The look on peoples faces the first time they sample a peated whisky is often priceless; they either like or they don’t. There is a scale to peated whiskies which can vary between a light smoky flavour and up to what can only be described as a ‘smoke blast’!

Peat has been used for hundreds of years in the production of whisky as a cheap and readily available source of fuel. However, as cheaper fuel options became available, thanks to the advent of the railways, the reliance on peat diminished in some areas over time.

In the major whisky-producing areas like the Lowlands and Speyside, the use of peat is the exception rather than the rule. In fact, some distilleries in the Speyside area have released peated whiskies which I believe are more experimental and most likely with marketing in mind than part of their core range.

What is Peat?

In order to understand the role peat plays in the whisky-making process, it’s important to understand what peat actually is and where it comes from.

When extracted from the ground and dried, peat is an amazingly effective fuel source the Scots have been using for centuries. The peat is usually extracted from ‘peat bogs’ which are a type of wetland. They occur in many different countries around the world which offer the right conditions; sufficient annual rainfall and cooler temperatures.

The actual peat bog itself requires a very specific set of criteria to form where groundwater sits close to the surface and a mixture of water-tolerant plants can grow like reeds. As the plants die they don’t decompose in the usual way, due to the surrounding water and low oxygen content, which can lead to the formation of a bog.

When peat is extracted from the bog it contains over 90% water and needs to be dried out. The most common method is to cut the peat into square chunks which are laid out over a larger area and left to naturally dry in the open air.

Have a look at the video below from Laphroaig which covers the extraction of peat for their distillery.

How does peat affect the flavour of whisky?

The smoky, or peated, flavours end up in whisky as a side effect of malting barley. In order for the barley to be in the right chemical state for brewing, it needs the grains to sprout which is achieved by a process known as steeping, essentially soaking the barley in water for a few days. After the grains have sprouted they need to be dried out and this is where the peat plays its part.

The grains are laid out over the floor, about 16″ deep, with the peat fired kiln below sending up the heat and smoke which dries the grains out ready for the next step in the process and at the same time, adding in the smoky flavours which will end up in the whisky.

Peated whisky regions

When it comes to Scotch, there are three main regions where you will find major distilleries located. Those are the highland (Speyside), the Lowlands and the Islands. As cheaper fuel became available, due to the advent of the railways, the Lowland and Speyside distilleries were able to switch over to coke, a cheaper alternative fuel derived from coal. This option was unavailable to the island producers like Islay, Jura and Skye so they continued the tradition of using peat to dry their barley. Each island produces a distinctive flavour above and beyond the peat and this has much to do with the type of flora in the region that contributed over the years in creating the peat.

A good example of the influence of flora can be found at the Highland Park distillery which is located on the Orkney Islands, North of Scotland. The island is well-known for its heather, a hardier plant that can survive in seriously cold and windy regions and for this reason, Highland Park is well known for its unique heathery flavour.

This is why the island distilleries are well known as peated whisky producers and most of their production techniques have remained unchanged over the years.

How is peat in whisky measured? – PPM

We’ve talked about how peat is used to influence the flavour of the whisky but you might be wondering how you can compare the strength, or peatiness, in the flavour from one bottle to the next.  Fortunately, there is a measurement we can use based on the PPM.

PPM stands for phenol Parts Per Million and is used to measure the phenol content of malted barley after it’s dried in the kiln but before it goes through the process of distillation; the process itself will cause the reduction of phenol content by around 30% to achieve a final figure. The PPM figure is extracted using High-Performance Liquid Chromatography which is often used to determine the individual chemical components that make up a mixture. 

What are phenols in whisky?

Naturally, phenols can be found in everything from creosote to decomposing organic matter; they can be synthesized and manufactured in a chemical form. Phenols are manufactured specifically for a wide variety of products that include many household products and medicines. There are also different types of phenols and peated whisky contains Xylenol, Cresol, Phenol and Guaiacol to name a few. The latter is largely responsible for the smoky flavours you experience when sipping on a peated whisky.

When peat is burnt in the kiln various chemical compounds are released; however, those we are interested in are the phenols. As the smoke from the fire surrounds the damp malted barley the phenols are slowly absorbed as we mentioned above.

The PPM level is at it’s highest during that part of the process but it will slowly drop right through the full distillation process. The longer the barley is exposed to the fire the higher the PPM and stronger the smoke flavour will be in the final product.

Whilst we use PPM as a measurement, it’s worth considering it as indicative figure when it comes to the flavour profile as other influences affect the final taste. Comparisons are also difficult as not all distilleries measure the PPM  at the same stage of production.

The strength of peat varies between the distilleries and you can work your way up the scale to the point where the smoke overpowers you, to give you an idea you can see the scale of some of the most commonly available peated bottlings.

Tasting Phenols

There is a limit to the amount of phenol, or smokiness, that a human tastebud will be able to detect so although the Octomore is far out there in terms of a PPM level it’s unlikely you would be able to tell it was over 15 times smokier than the Talisker. It is a smoke bomb and I would encourage you to give a sample a try if you get the chance but it’s probably reserved for serious peat lovers!

Best peated whisky for beginners?

As whisky is not cheap, and the last thing you need is a bottle of smoky whisky which tastes like the beach, I’d always recommend a live tasting if you can find one (or on Zoom these days). This is the best way to try a range of these types of whiskies to see if you like them or not.

If you are in the market for a bottle then I believe you can’t go wrong with a Talisker or a Bunnahabhain to start. The well-known island distilleries like Ardbeg, Lagavulin or Laphroaig are renowned for their smoky coastal whisky and might prove to be too much for a first experience!

I hope you’ve found this useful in understanding a little bit more about smoky whisky. It’s important to remember the different regions produce different flavours and you’ll need to taste them all to truly understand the flavours you enjoy. Personally, I don’t enjoy the smoky whisky coming from the islands as I often taste the salty influence from these regions which puts me off,  please let us know if you enjoy peated whiskies by leaving a comment below.