What is peat, anyway?

Sure, it’s a stock image, but it does a great job of showing what peat looks like!

Editor’s note: throughout this post, we’ll refer to Scotch as “whisky” and other products in general as “whiskey.”

Last week, we released our fifth batch of Peated Whiskey, an exemplar in the freshly-official American Single Malt Whiskey category. Peated #5 is full of smoky, oaky flavors balanced by subtle fruit, grain, and even green tea flavors. Of course, we think it’s a winner.

But before we go too far in singing the praises of our own whiskey, we should take a moment to address an opportunity for education.

While sharing Peated #5 with our recent Whiskey 101 classes, we discovered that while some have heard of peated whiskey, they’re not exactly sure what it is.

While they may be unsure why, many bring up Scotch whisky when asked about peat. Maybe an elder—a parent, grandparent, or other—is a fan of Scotch, and has waxed about the things that give Scotch its characteristically bracing, complex flavors. Some are even good at identifying the specific flavor of peat in a whiskey and would pass a blind taste test comparing a peated with an unpeated whiskey. However, the source of peat’s role in whiskey remains elusive.

In any case, knowledge of peated whiskey without knowledge of peat—and its role in making whiskey—can make peat’s inclusion in an American whiskey feel confusing, or even improbable. In the spirit of diffusing confusion in pursuit of appreciation, let’s review the nature, origin, and evolution of peated whiskey.

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Peat is a naturally occurring, turf-like substance found in and around wetlands across the globe, including the bogs of Scotland. But don’t mistake it for moss or mud; peat possesses qualities unlike those other substances.

Surprisingly, peat is combustible when dried. Despite its initial mushiness, peat can be cut into bricks and stacked (see above). This combination of qualities makes peat a convenient source of domestic fuel.

Wetlands dwellers have harvested and burned peat for warmth, cooking, and other applications for as long as anyone can remember. Peat even plays an important environmental role on a global scale, absorbing carbon like a sponge. In all, it’s a remarkable organic substance. But where does this magical muck come from?

Peat is the result of dead plant matter gradually collecting on top of itself, avoiding decay because of its relative acidity and submersion in water. Over thousands of years, peat continually accumulates and compacts itself, building at a rate of about one millimeter each year. The process is not unlike the formation of fossil fuels such as oil and coal.

So peat is densely compacted, decayed plant matter. Great! But still—how did peat end up in whiskey? Where the history of Scottish distilling and the natural ecology of Scotland intersect offers the answer.

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According to the Scotch Whisky Association, the earliest documented record of distilling in Scotland comes from tax records dated 1494. It’s safe to assume that if related taxes were being collected then, distillation was already commonplace.

Given they encountered distillation sometime during the Middle Ages, the Scots simply leveraged the most abundant natural materials on hand to make their whiskey. Because fields of barley and bogs of peat were in abundance, the Scots used barley as their primary grain for fermentation and peat as their primary heat source for firing their stills.

Industrialization eventually brought more economic sources of heat to all parts of Scotland. However, Scotch—and other whiskeys—are still peated today. Clearly, peat’s persistent influence on whiskey isn’t about heat.

What’s it about, then? It’s about flavor.

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The quick assumption about peat flavor in whiskey might be that peat is added directly to the whiskey. After all, the same “just throw some in there” approach works great for other kinds of whiskeys (e.g. Honey or Maple). However, as offensive as some may already find peated whiskey to be, such an approach would likely yield an undrinkable spirit. (And potentially poisonous?)

As it turns out, there are two steps in the Scottish style of making whiskey that require heat. On the one hand, there is the expected firing of the stills for distillation. On the other hand, though, is the key: the roasting of barley.

Since starting to distill in the Middle Ages, the Scots have roasted barley over burning peat to arrest the malting process prior to fermentation. Smoke rising from the peat seeps into the grains, adding flavors that continue through the rest of the distilling process.

This choice imparted a combination of smoky, earthy, and oily aromas and flavors that were fingerprint-unique to each distillery. Over centuries, neighboring Scottish distillers traded ideas about using peat: how much peat to burn; where, when, and in what shape to cut the peat; how long to roast the barley; whether to add other smoking agents; etc. This sharing accentuated local character and led to the regional styles of Scotch whisky that we still see today.

While modern technology offers more economical heat sources for the stills, only burning peat can still impart barley with the unique characteristics necessary to give Scotch its bold flavors.

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Fortunately, the secret of making peated whiskey didn’t stay in Scotland forever. While peat was specific to Scotch whisky for centuries, Scots brought their whisky-making approaches with them when they eventually traveled abroad to places like Canada and the U.S.

Additionally, foreigners who discovered Scotch whisky upon visiting Scotland would seek to learn from the Scots how to distill with peated malt, aiming to recreate the flavors of Scotch at home.

The use of peated malt in making whiskey is now a global pursuit; distillers everywhere have become interested in putting their own spin on peated whiskey.

Manatawny is part of this new tradition, as we plan to release a peated whiskey every year. It’s a lot of fun to experiment with barley sources, aging lengths, barrel finishes, and more to make a peated whiskey we enjoy. Through these whiskeys, we aim to build a bridge between respective Scottish and American flavors and traditions.

If you’re a fan of either Scotch or American whiskeys, you’ll surely enjoy Peated #5. As always, we encourage you to stop into one of our tasting rooms to try it and formulate your own opinion—firsthand!