Who doesn’t love delving into a spirit and learning all about the ingredients that have gone into it? The process. Where it all comes from and what it gives to the flavour… One of these fascinating ingredients, peat, has traditionally been at the epicentre of whisky production, especially in regions such as Islay in Scotland.
This article digs into the world of peat, what it contributes to whisky’s flavour profile, and the process distillers use to imbue it into their spirits…
What is Peat?
Not to oversimplify it here, but it’s mud. A very specific type of mud, mind. Peat is an organic material formed from the partial decomposition of plant matter in waterlogged conditions over thousands of years.
You predominantly find it in bogs and mires, where the slow decomposition process under anaerobic conditions fosters a rich, carbon-dense material replete with a spectrum of complex compounds.
Influence on Whisky flavours
Including peat in the whisky production process introduces a range of flavour notes. The most prominent flavours include:
Smokiness. The iconic smoky note is the signature of peat-infused whiskies, a characteristic achieved through the phenolic compounds present in peat.
Earthy notes. Peat lends a deep, earthy undertone, offering a robust and grounded tasting note that is cherished by many whisky drinkers.
Medicinal and iodine flavours. Peat can introduce medicinal flavours, often described as somewhat antiseptic or with notes of iodine.
There are more nuances than this, clearly. Moreover, the amount of peat in a whisky will not only reveal different aspects upfront, but it will also have a profound affect once diluted or mixed.
Top tip for bartenders – peat tends to be more prominent once whisky is diluted (phenols are hydrophilic). So when assessing a whisky with peat in it, it serves well to taste both neat and with a splash before you decide on the quantity / suitability for a cocktail.
How does peat get into Whisky?
Peat becomes part of the production process at the malting stage.
To recap on malting as a process – Barley is soaked in water to initiate germination. It’s then spread along a malting floor (traditionally) over a period of time. Once ready, it is dried in a kiln to reduce the moisture content and halt any further growth.
It is at this juncture that peat comes into play.
Kilning and peat-burning
Peat is introduced into the kiln where it is burned to generate smoke. The damp malted barley is exposed to this smoke, allowing the grains to absorb the phenolic compounds — the agents responsible for the characteristic peaty flavours.
Distillers carefully manage this process, as both the peat smoke’s intensity and the duration of the exposure significantly influence the whisky’s final flavour profile. The more you add to the fire in the kiln, the greater the dose. Meanwhile, the longer the exposure, the more that’s absorbed.
The concentration of phenols, measured in parts per million (PPM), is a critical metric in the peat infusion process. A higher PPM denotes a more peat-heavy spirit.
It’s a balancing act that factors quantity, how long for and in what condition (moisture level) the barley is in.
Challenges distillers face when incorporating peat
Most small craft makers buy in their all their malt from a specialist supplier, meaning consistency of their peated supply isn’t an issue.
That said, there are some who process raw barley all the way thorough to end spirit (New World Whisky Makers in Tasmania, for example). For those producers, achieving a consistent peat flavour profile over different production batches can be a significant challenge.
There’s not much they can do at that scale either. Natural variations in peat, changes in climatic conditions affecting the peat beds, and slight alterations in the production process (such as temperature, time of year) can result in inconsistency in the amount of absorption.
For most, this is the joy of small batch single estate /malt distilleries. It’s also true that just because the start point of the barley might vary, many blend batches to reduce variability before laying them to rest in casks. There’s also a lot of blending once mature too…
As a drinker tasting peat in a whisky, knowing about this fluctuation, knowing that this natural absorption is hard to do with uniformity and how it’s always marginally different is a reminder that what you are tasting isn’t just the natural production process. It’s been honed. It’s been dialled in. There is a lot of the distiller’s hand involved in ensuring the levels are right. So, while you can taste the material – peat – appreciate that you can also taste the craft of whisky making itself.
A more universal issue is regulatory and environmental concerns.
Peat extraction poses serious environmental concerns due to habitat destruction and carbon emissions. In fact, there are regulatory frameworks governing the extraction and use of peat. In many places of the world, distillers must adhere to environmental regulations and standards when using it.
Moreover, the depleting peat reserves press distillers to explore sustainable alternatives and conservation techniques.
Scotland’s peat soils cover close to 20 per cent of the country, with estimates suggesting they store around 1,600 million tonnes of carbon. But research has also found that 80 per cent of these peatlands are regarded as being degraded. It takes several hundreds of years to replenish…
This might seem an absurd point to make against whisky producers when you compare the quantities of peat being used vs other industries. The Scotch whisky industry equates to less than 1% of the total peat extracted in the UK each year. But the concerns are valid nevertheless.
Thankfully, through alternative sources to mimic some of peat’s characteristics and better kiln efficiencies, there’s a lot of ways distillers are already working to reduce the quantities needed.
It’s also worth keeping in mind that while all carbon removal is an issue and must be avoided, there are other areas where there is far more substantive and enduring sustainability gains to be made.
Rightly or wrongly, the sustainability of peat will continue to be a talking point for years to come.
Extra takeaway’s for curious minds digging further…
Knowledgeable bartenders and whisky aficionados should become familiar with the term “phenol parts per million” (PPM). It’s a metric that denotes the peat intensity in whisky. Some whiskies state the number on the bottle. But you can also use it as a way of thinking about what a whisky distillery does in a different way too…
Just like some Rum distilleries produce different ester marks, so do some Whisky makers with the levels of peated new makes.
This gives them blending options for their range once matured. Meanwhile, there are also distilleries who make specific types of peated whisky for use in blends by parent companies, while their regular single malt isn’t peated at all.
Peat can be a polarising flavour. It’s such a distinct aroma and unique flavour note. Using that distinct edge can create some of the most spectacular food parings. The robust flavour of peated whisky can be complementary to the likes of smoked meats, strong cheeses, and chocolate.
The way it lingers can be accentuated, altered and contrasted is an endless opportunity to create extraordinary moments.
Be it through food pairings or just through sipping a dram, peat is more than an ingredient. It is a storied element rooted in tradition, a beacon of geographical essence, and a gateway to a rich, multi-dimensional flavour landscape.
So there you have it. That’s peat introduced and hopefully no longer a stranger to be feared!
