What Gives Whisky Its Flavour? - The Role of Peat
Peated whisky is one of the most distinctive single malt whisky styles, known for its smoky, earthy, and maritime character. But what gives whisky its peaty taste, and why does it vary so much between whisky makers? In this guide, we’ll explore the history of peated whisky, tracing its roots to Scotland’s landscape rich in peat bogs. We’ll break down the science behind peat, the production process, and how cutting, drying, and distillation impact peat intensity. Finally, we’ll navigate the big difference in peat levels, helping you understand and appreciate the remarkable diversity within this smoky, complex whisky category.
- Understanding the history of peated whisky
- What makes a whisky taste peaty?
- Producing peaty whisky – what affects the peatiness?
- Navigating the world of peated whisky
Discover the origins of this distinct flavour in the peat-rich landscape of Scotland
Learn the chemistry behind peat and why it’s so sought after in the malt whisky industry
Understand how cutting peat, malting and distillation affect the peat qualities
Decipher the different peat levels and learn how diverse the category really is
Understanding The History of Peated Whisky
Peat is partially decayed organic matter that can be found in waterlogged, boggy earth. It is rich in carbon, which makes it a good fuel source – use of peat was common in rural Scotland and Ireland, where peatlands were abundant. Peat was burned for all sorts of reasons, one of them being the malting process in malt whisky production. Barley is soaked to trigger germination, and the grains must be dried to halt the process.
Peat fires infuse the grains with a distinctive smoky, earthy flavour that persists all the way through distillation. This unique flavour became synonymous with Scotch and is still widely used today despite access to alternative fuel sources with a lower environmental impact. The final flavour of peated malt whisky is so desirable that many New World regions, such as Japan and Canada, infuse their grains with peat smoke.
What Makes a Whisky Taste Peaty?
The smoke from the peat fires used to dry malted barley is responsible for infusing the grains with a distinct smoky profile. However, peat is a unique fuel source that comes with an unmistakable flavour profile compared to wood or coal. Due to its high moisture content, heavy smoke, and low sulphur content, peat smoke creates a richer, yet more pleasant flavour than wood or coal.
What Defines Peat in Whisky?
Peat flavours are obviously characterised by heavy smoke. However, the dense carbon content and partially decayed vegetation are also responsible for earthy, herbaceous and medicinal flavours which vary from region to region. Explore the chemical compounds responsible for peaty flavours:
- Guaiacol – Produces the classic smoky and woody aroma.
- Syringol – Contributes to a sweeter, campfire-like smoke.
- Cresols – Imparts medicinal, tar-like, or antiseptic notes reminiscent of iodine or TCP.
- Phenol – Adds an earthy, herbal, and slightly burnt aroma.
- 4-Methylguaiacol – Brings spicy and meaty undertones reminiscent of a barbecue.
How Peat Influences the Chemical Composition of Whisky
During the drying process of peat whisky production, the heavy, phenol-rich smoke is absorbed by the barley kernels, acting like a sponge. These phenols remain during the fermentation process and can interact with other by-products, slightly altering flavours and yields.
Smoke-derived phenols are heat-stable, which means they comfortably travel through distillation into the final product.
Finally, the lightest phenol chains are the fastest to break down - these offer forward smokiness. With age, peated whiskies mellow and complexify, leaving behind longer-chain phenols and a deep richness – expect flavours of leather, tobacco and spice.
Producing Peated Whisky – What Affects the Peatiness?
Peat Composition & Source
The chemical composition of the peat depends on two main factors – location and depth. Surface peat contains more fresh, herbaceous and floral flavours. Whereas, at deeper levels, the peat is rich in medicinal and earthy qualities.
The flavours of the peat are heavily influenced by the types of plants that grow there, such as moss, heather, shrubs, grass, worts or ferns.
Moisture Considerations
Peat with higher moisture content burns more slowly with a heavier smoke. Meanwhile, too moist and doesn’t combust properly. The moisture content of the germinated barley is also crucial - damp grains absorb more smoke.
Duration of Peat Smoking
The longer the barley spends in the peat smoke, the stronger the final flavour. Generally, lightly peated expressions spend less time in the kilning process.
The Distillation Process: Refining Smoky Flavours
The various smoky phenols will boil off at different temperatures, which means that distilleries can decide when to cut the spirit for their desired flavour of the final product. Most of those rich, smoky flavours have higher molecular masses, so they boil off later in the process. Late cut points capture those unctuous, oily and smoky characteristics.
Moreover, the type of stills influences which flavours make it through distillation. Pot stills retain a lot more of those heavier, longer-chain phenols. Column stills produce a lighter spirit with less pronounced smoke. The amount of reflux (evaporating and condensing) and the distillation rate contribute to the spirit’s clarity.
Finally, the number of distillations varies between producers; the more times a batch is distilled, the fewer the impurities and heavier phenols it contains.
Navigating the World of Peated Whiskies
How Can Peat Levels Vary Between Distilleries?
Originally, when peat was the predominant fuel source, there may have been fewer options for lightly peated styles. However, modern distilleries can now fine-tune the amount of peat they use. Explore how different levels of peat can be crafted by tweaking production techniques.
- Subtle Peat: Use of peated casks, column or triple distillation, early cut points or very short smoking periods.
- Light Peat: Use of triple distillation, surface peat, early cut points and short smoking periods.
- Medium Peat: Use of double pot distillation, moderate smoking periods and generous cut points.
- Heavy Peat: Use of pot distillation or downward-angled lyne arms, long smoking periods, late cut points, longer maturation and deeper peat sources.
- Intense Peat: Use of low reflux distillation (downward-angled lyne arm), late cut points, moderate maturation lengths and the barley is fully dried under peat smoke.
Whisky Producers: Cotswolds Distillery, Auchentoshan & Springbank
Whisky Producers: Highland Park, BenRiach, Talisker
Whisky Producers: Bowmore, Ardmore, Kilchoman
Whisky Producers: Laphroaig, Lagavulin 16, Ardberg
Whisky Producers: Octomore (the peatiest in the world), Legaig, Lagavulin 12
Identifying Different Levels of Peatiness in Whisky
Typically, the level of peat can be estimated by testing the concentration of phenols in the barley. However, because the phenols are measured in the malt (before fermentation and distillation) the amount of peat in the final whisky can change.
Phenols are measured in parts per million (PPM). Here is a general guide below:
- Unpeated Malt → 0–5 PPM
- Lightly Peated Malt → 5–15 PPM
- Medium Peated Malt → 15–30 PPM
- Heavily Peated Malt → 30–55 PPM
- Extremely Peated Malt → 55–300+ PPM
Nuances in production will affect the peatiness of the whisky, so consider the following:
| What makes a whisky peatier than expected | What makes a whisky lighter than expected |
|
|
Recommendations for First-Time Peated Whisky Tasters
- Cotswolds Peated Cask Single Malt Whisky: Aged in peated quarter casks, subtle flavours of smoke, sweet vanilla, and tropical fruit make this an exceptionally moreish dram.
- Talisker Skye: Gently smoked, this Scotch whisky expresses honey, citrus, black pepper and maritime peat. Its approachable profile makes it a great starter whisky.
- Springbank 10: Two-and-a-half times distilled, this whisky offers soft, approachable peat with oily, maritime and briny notes which aren’t overpowered by smoke.
Frequently Asked Questions
How should I pair peated whisky with food?
Peated whiskies usually pair well with robust flavours. Savoury recommendations include blue cheese, charcuterie, twiglets, miso nuts, anchovies or crispy seaweed. Dark chocolate, sea salted caramel or espresso are excellent dessert pairings.
Is age a factor in the taste of peated whisky?
Yes, longer ageing periods result in deeper, mellow and more complex flavours with more intricate smoke profiles. You may get a softer hit of peat with more emphasis on leather, earth, umami, tobacco and herbs coming through on the finish.
Tips for storing peated whisky to preserve its flavour
Exposure to heat, light and oxygen causes smoky phenols to degrade over time, so it’s important to keep your peated expression in a cool, dark spot (you can use the original storage box). Store upright, and tilt the bottle to wet the cork every 6 months if you’re ageing a bottle for 10+ years.
Is there such a thing as lightly peated whisky?
Yes, lightly peated whiskies are quite common. They usually rely on short smoking periods, triple distillation or column stills to craft a light, pure and smooth spirit. Learn how to choose a lightly peated single malt.
How is smoke measured in whisky?
Smokiness is estimated in relation to the amount of phenols present in the malt before fermentation. This is measured in parts per million (PPM). Lightly peated whisky will have 5- 15 ppm, heavily peated malts with have over 50 ppm.
What to read next
How does cask selection influence whisky flavour