The Serious Eats Guide to Single Malt Scotch

Last week, we examined the distinction between single malt and blended Scotch whiskies. Today, we'll step back a bit and take a more detailed (much more detailed) look at the single malt. I'll describe what single malts are, explain how they're made and aged, discuss the concept of Scotch terroir, and explore some of the regional variations.

Grab a tasting glass and let's get started!

What Is Whisky?

The word whisky derives from a Gaelic term uisge beatha, or "water of life." This latter term may seem familiar to you; it's also reflected in the Latin aqua vitae, the French eau de vie, and the Scandanavian aquavit.

Defined, whisky is simply a distillate made from fermented grain mash. It does not necessarily need to be aged.

What Is Scotch Whisky?

Barley field. Wikimedia Commons

Scotch whiskey is more specific; it has the following required characteristics:

  • It must be made in Scotland...
  • ...From water and malted barley.
  • As we saw last week, it may contain other cereal grains, such as corn and wheat, but it must contain barley.
  • It must be converted into a fermentable substrate only by endogenous enzyme systems. What in the world does this mean? I'll discuss this later.
  • It must be fermented only with yeast.
  • Scotch can be distilled to no higher than 94.8 percent alcohol by volume (ABV), and bottled at at least an ABV percentage of 40 percent. (In practice, most Scotch is distilled to about 60 to 65% ABV.)
  • Scotch must be matured in oak casks, in Scotland, for no less than three years.
  • Nothing may be added to Scotch whisky except water, caramel coloring, or a combination of both.
  • A person must not manufacture any whisky in Scotland except Scotch Whisky.

Single malt Scotch goes a couple of steps beyond these requirements:

  • It may be distilled in one or more batches...
  • ...At a single distillery...
  • ...From water and barley alone (no other grains).
  • Finally, it must be made in pot stills. Other Scotch whiskies may be made in column stills, but not single malts. So, in other words, if you buy a blended whisky such as Dewar's, some of the grain whiskies in the blend may have been column-distilled, but if you enjoy a single malt such as Dalmore, all the whisky in the bottle is from pot stills.

Scotch Production: Malting, Mashing, and Fermentation

Malting floor at Highland Park Distillery. Wikimedia Commons

Scotch whisky starts with malted barley, water, and yeast. Whole kernels of barley don't ferment well, so distillers need to take an additional step and first partially germinate the barley; they steep it in water to allow it to begin to sprout. The barley is then dried on a malting floor, which is a perforated platform. Heated air is forced through the perforations, drying the barley. In some cases, distilleries use smoke, usually from burning peat, to dry the barley and impart a smoky flavor. We'll talk more about peat and smoke a little later.

This process releases enzymes that break down the starches in barley and convert them to sugars; this allows yeasts to begin the process of fermentation. Earlier, I mentioned the term "fermentable substrate." That's what the malting process produces. "Endogenous enzyme systems" refers to the enzymes that malting produces, those that originate from within the grain itself. This language is important; whisky producers in some countries are allowed to add enzymes. Scotch producers are not allowed to.

Traditionally, distillers malted their own barley, produced on nearby farms. A few places still do this—although even those places supplement their own malt with purchased malt—but most distilleries these days purchase malted barley from large producers.

The dried malt is then ground into a flour, mixed with hot water, and allowed to steep. It's during this steeping process, which is called mashing, that the enzymes released in malting convert starches to sugars. Yeast is added, and this liquid—called a "mash"—begins to ferment.

"Wait a second, did you say malted barley, water, and yeast? Isn't that beer?" Yes; you can think of Scotch as a beverage that starts as a beer, albeit one that's produced without hops. This "beer" goes into the still at about 5 to 7 percent ABV.

Scotch Production: Distillation

Pot stills at the Lagavulin Distillery. Wikimedia Commons

No one knows exactly how or when distilling reached Scotland. Some theories have it reaching the Scots via Russia and Scandanavia; others say it arrived via Ireland. What we do know, from examining historical documents, is that by the time Columbus sailed west across the Atlantic, a friar in Fife was purchasing malted barley to make a distilled spirit.

Single malt Scotch, by law, must be distilled in copper pot stills. The advantage of using pot stills rather than column stills is that pot stills retain more of the character, texture, and flavor of the original mash. (Column-distilled liquor is closer to pure alcohol, with congeners and other flavor enhancers removed during the distilling process. By law, distillers are allowed to add some column-stilled product to blended Scotch.)

Scotch Production: Aging

Anything labeled and sold as Scotch whisky needs to be aged in oak casks for at least three years. This is true of every product that carries the "Scotch" name: single malts, single grains, blended malts, blended grains, and blended Scotch. (For more information on these various types of blends, see last week's article.)

UK law carries no provisions about the source of the casks used to age Scotch. In the United States, by contrast, Federal law states that only brand new charred oak casks may be used for aging bourbon whiskey. Now, this difference between UK and US law has two implications. The first is that UK law isn't so specific: it just says "oak casks." Scotch distillers can use any type of oak cask to age whisky—either new or previously used. Distillers can use casks that previously held bourbon, rye, sherry, port, madeira, rum, or brandy, for example. The second implication is that if bourbon must be aged in new casks, there are a lot of second-hand bourbon barrels on the market. Where do most of them go? Scotland. Most Scotches on the market today are aged in former bourbon barrels.

Why don't Scotch distillers use new barrels, like bourbon distillers do? There are three reasons. The first is economic: used barrels are simply cheaper than new ones. Additionally, new barrels impart stronger woody notes into the flavor and aroma of a whisky. Scotch makers consider those strong woody notes to be un-Scotch-like. The third reason is innovation: using previously filled casks allows Scotch makers to subtly influence the final character of a dram of whisky. A Scotch aged in a sherry cask takes on the nutty and floral notes of a great sherry, for example.

Maturation and Age Statements

Some, though not all, single malts carry age statements. These may refer to a single calendar year—for example, 1990—or they may describe the age of the whisky—for example, 15 years old.

If a whisky displays a calendar year, all of the whisky in the bottle was distilled in that year. If a whisky displays an age, all of the whisky in that bottle is at least as old as that age—for example, it's all at least 15 years old—and some of the whisky may be older. In practice, though, it's not in a distiller's interest to include whiskies that are much older than the age statement. So in a bottle marked "15 years old," don't expect that any of it is, say, 21 years old. The whisky is likely to all be about 15 to 18 years old.

Terroir and Flavor

Scotch makers speak of terroir in their product in much the same way that winemakers do. Generally speaking, the things that are unique to a given single malt are matters of tradition, recipe, and technique, not geography. The use of peat smoke is one example, as is the decision whether to use bourbon or sherry barrels.

On the other hand, the late whisky writer Michael Jackson wrote of scientific studies that suggest a link between the flavors of a malt, the sources of water used in distilling, the fields of heather through which it flows, and the rock formations from which the water sources arose. So some of this talk of terroir is hype and marketing, but that's not to say it's all nonsense. Geography does affect the flavors and aromas of Scotch, often in subtle ways.


Whisky loves temperate, damp climates, such as those of Scotland and Ireland. These regions are great for barley production, and even better for helping to achieve unique character of Irish and Scotch whiskies. Why? As whisky ages in a barrel, it expands and contracts into the wood as temperature fluctuates. The greater the temperature fluctuation, the faster spirits age. Scotch, in a temperate climate, ages more slowly than does bourbon, in the more volatile climate of Kentucky. This is also a reason that Scotch can easily age for 20 or 30 years, whereas bourbons of such age are rare and expensive.


Peat in Lewis, Scotland. Wikimedia Commons

I mentioned earlier that after barley is germinated, it gets spread across a malting floor and dried by the use of forced hot air. Historically, the "air" was peat smoke, but today, more energy-efficient means of heating air exist, and peat smoke is now specifically used as a flavoring component. (To this day, peat is harvested from bogs and moors as a source of fuel, and even energy production, in some parts of the world.) If you've ever had a smoky Scotch whisky, such as the single malt Laphroaig, or the blended malt Peat Monster, you've had a peated whisky.


The regions of Scotch whisky. Wikimedia Commons

Geographically, the world of single malts is divided into five regions. These regions are protected in UK law, to ensure that a Scotch that's labeled with a certain region is actually made in that region. The five regions are Speyside, the Lowlands, the Highlands, Islay, and Campbeltown. Don't invest too much meaning in these regions. Historically, they played a larger role in single malt variations than they do today. But people still speak of the regions, so it's worth a general, broad look at them.


The region with the most distilleries, Speyside is located geographically in the center of Scotland. Speyside malts encompass a range of varying characters and styles, which is one reason such geographic classifications are no longer so meaningful as they were historically. Aberlour and Macallan, for example, sherry-ages many of their whiskies, producing a nutty, fruity dram. Balvenie carries notes of honey and orange, whereas its neighbor, Glenfiddich, tastes more of raisins and chocolate. Flavor and character in these malts depends more on house style than any regional characteristics. Other Speyside distilleries include Cardhu, Cragganmore, Glenfarclas, and Glenlivet.


Whiskies from this region are traditionally triple-distilled, making them smooth and light in character, much like Irish whiskies. (Malts from other regions are generally double-distilled, giving them richer character and a thicker body.) For this reason, Lowlands malts are often a good place for Scotch novices to begin. One well-known Lowland is Glenkinchie. A light, rounded, and flowery dram, it's great for beginners. As a bonus, the distillery is located near Edinburgh; it receives visitors and makes for a convenient side trip. Another option is Auchentoshan; triple-distilled, it's sweet and delicate and another option for newbies. Located near Glasgow, it's also a very accessible distillery for a side trip. The only other Lowland whisky currently produced is Bladnoch.


The Highlands encompass a huge region and a lot of distilleries, including the islands near the Scottish mainland (excluding the island of Islay). Drams are produced here in many different styles, and so it's difficult to generalize about a "Highland style." I started drinking Scotch with Glenmorangie, mainly because you can pretty much find it everywhere. A creamy and well-balanced whisky, Glenmorangie is the best-selling single malt in Scotland. The distillery regularly puts out special releases: whiskies aged in port or sherry casks, extra-mature releases, and limited-edition bottlings.

I've moved away from Glenmorangie in recent years to try other brands, though. Among my current favorites are Dalmore, Isle of Jura, and Highland Park. Although all three brands have pricy, limited-edition bottlings available, you can skip those and stay with the entry-level releases, all of which are well-balanced, reasonably priced whiskies with individual character and great depth of flavor.

In considering the range of styles available in the Highlands, I must mention Talisker, from the island of Skye. Talisker is a rich, heavy, and smoky malt—not as hugely peated as, say, Lagavulin, but definitely noticeably smoky. Talisker is a great introduction to the peatier side of Scotch, for someone who wants to start exploring those flavors and aromas.

Other Highlands brands include Balblair, Clynelish, Pulteney, Glen Garioch, Lochnagar, Ben Nevis, Dalwhinnie, Glengoyne, Loch Lomond, Oban, Edradour, and Scapa.


Here we go, the peat bombs. All but one bottling distilled on Islay is peated; Bunnahabhain is the exception, a sweet and nutty whisky that should appeal to any Scotch drinker. Bruichladdich produces a lightly peated drink, subtle compared to its neighbors. It's a good intro for someone crossing over into peatier styles. Beyond that, the other distilleries on the island all produce whiskies with varying ranges of peat, from mid-range to heavy. Other stylistic differences among these whiskies involve secondary flavors: Ardbeg, for example, is earthy and salty, whereas Laphroaig is iodine and medicinal. Other brands include Bowmore, Caol Ila, and Lagavulin.


The smallest of the whisky regions, Campbeltown was historically among the most active, with over 30 working distilleries. Now, though, things have changed, and the region is reduced to two: Springbank and Glen Scotia. Springbank is my current favorite Scotch; I'm presently working my way through a bottle of the 15-year-old that my wife got me for Christmas. It's a moderately peated Scotch, with the smoke held in check by other flavors, including a rich maltiness, some brineyness, and a sweet nutty taste.