Are you wanting to know more about peat and smoky whiskies? Want to know what makes a whisky smoky in the first place? Peat is one of the least understood aspects of the whisky industry, but fear not: Our complete guide to peat will make you an instant expert on the topic.
Most whisky drinkers will remember and can pinpoint the first time they tasted a heavily peated whisky. Like a fork in the road, it was probably a “love it or hate it” moment….there is rarely middle ground or ambivalence when your tastebuds first encounter a truly peaty, medicinal, smoky whisky. But things change…
Would it be crude to suggest that Scotch whisky drinkers thus fall into three camps? There are those that hate peated whisky; those that love peated whisky; and those that are actively and earnestly transitioning at some point between those two extremes. No matter where you sit on that three-pointed scale, this guide will assist you in understanding all the ins and outs of peat and the role it plays in Scotch whisky. (And we’ll touch on Irish whiskey, too). So settle in with a dram of your favourite malt and let’s cover some facts and dispel a few myths….
What is peat?
In simple terms, peat is partially-decayed organic material found in the ground. It is a combination of earth and old vegetation (i.e. grasses, reeds, lichens, shrubs) in wet boglands that slowly – over hundreds or thousands of years – compresses into a dense, clay-like mud. Think of it as pre-pubescent coal! There are very specific and certain conditions in the soil that are required for peat to form (as well as necessary climatic conditions), and so it is only found in a limited number of regions on the planet.
Cut from the ground by hand – usually no more than a metre or so from the surface and then allowed to dry out – peat is a slow-burning fuel that can be burned to give off heat. In the case of peats found in Scotland and Ireland, burning peat gives off a little bit of heat, and a lot of smoke.
If you’re interested, you can also click here for an excellent, short little video by Laphroaig’s former distillery manager, John Campbell, as he demonstrates cutting the peat, and explains what makes Islay’s peat – and particularly that of Laphroaig’s – unique.
What makes whisky peaty (and smoky?)
In order to make alcohol, you need water, yeast, and sugar. In the case of Scotch malt whisky, the sugar comes from a cereal grain, i.e. barley. But, unlike grapes and the making of wine and brandy (where the sugar is found naturally in the juice), we can’t just squeeze a cereal grain to access the sugar. No, first, the barley needs to be malted. Malting is the process of converting starches in the grain into sugars, and this is done by steeping the barley in water to kick-start germination. Once germination is underway, the wet barley is laid out on a floor where the starches slowly convert to sugar to provide energy and sustenance for the growing plant. However, if germination was allowed to complete its course, the budding plant would consume all its own sugar….which we don’t want to happen! Germination is thus abruptly halted by drying the barley out. Traditionally in Scotland, the barley was dried over a fire fuelled with peat.
As mentioned above, burning peat gives off heat, but also smoke. As the wet barley dried out, it would absorb the smoke from the burning peat, and thus “capture” its peaty, smoky characteristics. It’s essentially an infusion. Modern distillers thus design how peaty and smoky a whisky becomes by controlling how much peat smoke is used to dry out the barley. In order to produce the really peaty whiskies, they’ll burn lots of peat over a long period (say 20 hours); and if they want to make a whisky that is completely non-peated, they’ll simply dry the barley with hot air. You can see the difference in the two images below…
The myths and misunderstandings about smoke in whisky
Some creative story tellers and a few ill-informed brand ambassadors from years gone by would have you believe that your whisky is smoky due to other processes or features of whisky production, but they’re usually wide of the mark. Here are some common misconceptions:
- Whisky is smoky due to Scotland’s peaty water. No, not quite. Whilst the water used in the production of Scotch whisky might pick up trace elements of peat as it runs over hillsides or rises through springs, these elements (i) don’t make it through the distillation process, and (ii) don’t impart peaty/smoky aromas and flavours.
- The smoke comes from charring the barrels that the whisky matures in. No, not even close. Charring the barrels produces a layer of charcoal in the wood that acts as both a filter and a purifier for the maturing spirit – but in no way does it impart smoke into the spirit.
Are peat and smoke the same thing?
Actually, no! You can have a whisky that is peaty without being smoky, and you can have whiskies that display smokiness, yet without the accompanying traits of peat. Furthermore, there are some characteristics of peat/smoke that you can smell but can’t taste, and the opposite is also true, i.e. a whisky might have burnt or smoky characteristics that you can taste but cannot smell.
Smoke – as perceived in a whisky – is obviously associated with something that is burnt or burning – it is the byproduct of combustion. Peat, in contrast, is typically perceived as a more earthy and organic characteristic…it might display itself with traits of forest floors, potting mix, humus/compost, etc. And, in the case of peat that comes from more coastal locations (or areas that once previously were coastal or under sea), you’ll also get those iodine-like, briny, maritime notes.
It all comes down to the chemical composition of the peat that is used when drying out the barley. The carbon compounds that form part of the combustible fuel in peat are called phenols. There are different sub-types of phenols, and they impart different characteristics to the barley – and, thus, the whisky. Without getting too scientific, examples of these different phenols include:
- Phenol – this is responsible for delivering the medicinal, iodine-like characteristics that are often described as or likened to antiseptic, TCP, etc.
- Guaiacol – this is responsible for burnt and smoky notes, but it’s discernible in taste only.
- Syringol – also responsible for burnt and smoky notes, but discernible in aroma only.
- Cresol – this is responsible for the medicinal characteristics that are a bit more organic, i.e. earthy peat, tarriness, moss, and coal-tar notes.
Not surprisingly, the chemical composition of peat varies tremendously, depending on where it comes from. This is one of the reasons why peated whiskies from Scotland’s mainland (e.g. Ardmore or Benromach) taste very different to the peated whiskies from Islay. Even the depth that the peat is retrieved from will have a bearing on the resulting flavour of the malt: Peat sitting one metre below the surface will have different characteristics to layers sitting two metres below the surface in the same dig. Distillers are very specific about the depth and character of their cut peat to ensure they get the right outcomes.
What is “ppm” ?
Read anything about peated whiskies and it won’t be too long until you encounter the letters ppm. It stands for parts per million, and it’s the measuring stick for how much peat is in the barley after the malting process.
As discussed above, the actual compounds that contribute to peatiness and smokiness in a whisky are phenols and we thus measure the phenols in parts per million. When whisky producers are aiming to produce a peaty/smoky whisky, they instruct or specify the phenol levels they desire in the malt.
It’s at this point we can start to make some generalisations about peating levels and begin to compare different whiskies. Each distillery obviously has a unique house style or flavour profile that it sets out to achieve, and thus they specify the peating levels that will deliver that profile.
Some distilleries aim for no peat whatsoever. (Glengoyne being a good example. Regular-make Bunnahabhain is another). The vast majority of Speyside/Highland distilleries specify “Highland peat”, which weighs in with a peating level of 1-3ppm phenols. Most whisky drinkers will not discern peat or smoke at these levels, particularly if the sourced peat has a higher syringol content.
It is the island or coastal distilleries where things start to get more interesting. Talisker has a wonderful iodine, ozone-like character with its malt peated to around 14ppm. Similarly, Highland Park has an earthy, floral malt peated to 12-15ppm. (Highland Park is interesting in that it peats its own malt on site to around 40ppm, but then mixes this with malt from the mainland at 1-2ppm to achieve its final malt specification). The whiskies of Campbeltown typically exude a dirty, engine room-like peatiness, with Springbank peated to 12-15ppm, and Glen Scotia coming in at similar levels for its regular make. Arran and Jura both make heavily peated variants for small portions of the year. Kilkerran (distilled at Glengyle) has produced a diverse range of whiskies from medium to heavily-peated malt that typify the Campbeltown style.
But, of course, no comparison of peated whiskies will advance far without looking at the distilleries of Islay. Bowmore generally kicks things off with a relatively genteel 25ppm. Caol Ila, Laphroaig, and – these days – Lagavulin all feature malt peated to 35ppm. Bruichladdich’s Port Charlotte variant is 40ppm, and Ardbeg is 50-55pm. Kilchoman varies between 20 and 40ppm, depending on the particular campaign being produced, noting they produce their own malt on site, as well as using the same malt specified by and supplied to Ardbeg. No, we haven’t forgotten Octomore…we’ll come to that in a moment.
Why you shouldn’t rely on ppm levels…
It’s important to appreciate that the peating level, expressed in parts per million of phenols, is not the sole or governing factor that determines how peaty or smoky a whisky will be. It’s not really a number you should hang your hat on if wanting to know how peaty a whisky is. As we’ve established already, a lot comes down to the chemical composition of the peat and where it comes from. As a great example, Kilchoman whisky peated to 20ppm phenols smells and tastes significantly smokier than, say, Benromach’s peated release at 67ppm.
Secondly, distilleries have more tricks in their cupboard to shape a whisky’s character than the initial phenol level in the malt. The nature of their fermentation; the shape of the still; and how quickly or slowly they run the wash and low-wines through the stills will have a tremendous influence on how much of the phenols are retained in the final spirit and subsequently put into barrel. Another critical factor is when the distiller takes the “cut”. Most of the phenols come through in the late / final stages of the distillation run, and so a distiller can either capture or discard some of the phenols by designing when they stop collecting the “middle cut” and switch over to the feints.
A great example of this is to compare Lagavulin and Caol Ila. The two distilleries both use identical malt from the same source and malting facility, peated to 35ppm. And yet, the whiskies produced at each distillery respectively have very different peaty/smoky profiles – all due to the different fermentations, still shapes, and distillation regimens. (Whisky & Wisdom has written about this in more detail previously – you can read that article here. You might also be interested to learn that Lagavulin is not as peaty as it used to be! You can read more on that item here).
This is also the reason why Bruichladdich’s Octomore variant – famously peated to phenol ppm levels of 160 and higher – surprises many by being a far more refined, sweet, and cultured affair than the brutal ash tray they expect. Octomore employs an unusually long fermentation to produce a fruity wash, followed by a slow distillation that doesn’t delve too deeply into the feinty end of the run. The result is a balanced dram, rather than an incinerator.
For a more specific discussion on why you shouldn’t get too hung up on the phenol ppm levels in whisky, read Whisky & Wisdom’s other article, When fixation on peat and PPM gets OTT
The impact of age: Older whisky will not be peatier whisky
As we’ve already established, the initial phenol levels in the malt will not carry through to the final spirit. Both fermentation and distillation will see the phenol levels reduce. The third influencing factor is age. Put simply, phenol levels reduce with maturation in the cask. The peatiest, smokiest commercially-available whiskies will typically be young, say six to eight years old. Whiskies matured to older ages – say 12 to 18 years – will obviously take on more cask influence and complexity, and hopefully become more refined and multi-dimensional. But the original peat and smoke will slowly diminish with time in the barrel. This is one reason why some whisky drinkers can occasionally be underwhelmed or even disappointed after shelling out a small fortune for an Islay whisky that’s 25 or 30 years old, only to find that it’s not the smoky beast they’d hoped for. (Of course, a well-produced and well-matured whisky aged to 25 or 30 years in a quality cask will offer plenty of other delicious and redeeming qualities).
Peated whiskies from the mainland
In the second half of the 20th century, a small number of mainland distilleries were distilling spirit from malt that was peated to slightly higher levels than the norm. Glen Garioch was a great example, although that stopped in 1995. Similarly, Ardmore has always been medium-peated at around 12-14ppm to suit its parent company’s blending requirements, although more heavily peated runs are also undertaken on occasion. Loch Lomond distillery, responsible for producing 11 different styles of single malt, has several at the more peated end of the spectrum, with its Croftengea variant weighing in at around 40ppm.
However, for the most part – traditionally and historically – the really heavily peated whiskies came from Islay. Whilst heavily peated whisky was occasionally produced from mainland distilleries to suit blending needs or shortfalls in production (Brora being the prime example), they were sporadic, experimental, or makeshift campaigns at best. This started to change from the late 1990’s onwards, due to (i) Islay’s overall production levels being unable to keep pace with the industry’s needs and forecasts, (ii) several companies wanting to source peated whisky from within their own portfolio and facilities, rather than buy it from the companies that owned the Islay distilleries, and (iii) to market peated whisky to a fast-growing consumer base that was increasingly showing a love for peated single malts.
The once-rare prospect of a peated whisky from the mainland is now surprisingly common, and many distilleries offer a peated variant or expression in their commercial or official portfolio. Benriach was an early player when they released their Curiositas. Benromach turned heads a few years ago with its (very delicious) Peat Smoke release that was peated to 67ppm. Edradour produces a heavily peated variant under the name of Ballechin. Knockdhu (bottled as AnCnoc) has produced several peated variants since 2004. Similarly, Glenturret’s peated variant is known as Ruadh Maor. The list goes on: Glendronach has produced peated spirit, as has Ailsa Bay, Balvenie, Allt’a Bhainne, and Glen Moray. Newer distilleries that have launched in just the last few years have had peated campaigns right from the start – Ardnamurchan and Glasgow being two good examples.
However, it’s important to realise that the vast majority of peated releases from the mainland smell and taste very different to their Islay counterparts. The reason, again, is geology and the chemical composition of the peat – the dry iodine and mossy tarriness that is front and centre of whiskies like Lagavulin, Laphroaig, and Ardbeg is rarely replicated on the mainland. Many of the peated whiskies from the mainland also lack the maritime characteristics and brininess of the Islay whiskies. Whether that’s a good thing or bad thing is, of course, entirely subjective and up to you.
What about Ireland and Irish whiskey?
Ireland shares similar geological and climatic features with Scotland, and is thus also abundant with peat. Peat has long been a traditional fuel for villages and rural communities, and it would no doubt have been the traditional fuel for drying the barley before the commercial distillers adopted coal. Commentary varies from within and outwith the industry, but there’s a commonly held suggestion that peated whiskey more-or-less disappeared from Ireland from the mid-to-late 19th century onwards, until being revived by the Cooley Distillery in the 1990’s with its Connemara release.
Of course, it should also be appreciated that peated whisky and traditional Irish whiskey are actually somewhat conflicting or incompatible concepts! As we’ve discussed above, the phenolics come through in the late stages of the spirit run, and each distillation refines the spirit and removes the phenols. Traditional Irish whiskey is triple-distilled, and thus the impact of any peated malt will be tremendously reduced (if not nullified) by the end of the process. It is worth noting that Connemara is thus double-distilled.
Further reading…
If you’ve a particular interest in peat and some of the abovementioned distilleries, Whisky & Wisdom has written quite a number of articles over the years that address or expand on some of the items and whiskies explored above. For further reading you could check out….
Lagavulin or Laphroaig – which is better?
Islay – Its distilleries and its whiskies
Age is just a number: The truth about young whisky
Benromach Distillery – Speyside’s little jewel
When fixation on peat and PPM gets OTT
Cheers,
AD
PS: All images in this article – bar one, as credited above – taken by and (c) Whisky & Wisdom
PPS:. If you enjoyed this article, you might also like our other “explainer” articles:
The complete guide to non chill-filtered whisky
The whisky lover’s complete guide to sherry
The complete guide to oak, casks, & whisky maturation
The 1980’s heavy metal guide to whisky
Oxidation – does whisky go off in the bottle?
Very interesting article, thanks. One correction: malting does not convert starches to sugars, it prepares the starches for conversion, breaks down the barrier around the starches and creates the enzymes which catalyse the conversion. Mashing converts the starches to sugars, with the aid of the enzymes.
An interesting article, and very helpful indeed… although a slight innaccuracy. The charring of the barrels can, in some instances, impart a smoke character.
The thermal decompositon of lignen, at medium high temperatures during the toasting and charring process, produces a polyphenol called Guiacol which has a BBQ/Sweet woodsmoke flavour, highly soluable in alcohol, and generally fairly prevalent in many whiskies, even those that are unpeated. Whilst it is not solely responsible for “peated” smoke flavours, saying that “in no way does [toasting and charring] impart smoke into the spirit.” is probably a little inaccurate.
Thanks for the great article!