The Subtle Science of

Scotch Whisky

Rachel Barrie, Master Blender




July 6, 2012

No one has ever said that women are overrepresented in the beaker- and-Bunsen-burner world of science, though at least they have had more chances there than in the tweed-and-testosterone world of Scotch whisky. This makes Rachel Barrie a double anomaly—a chemist whose work crafting celebrated Scotch malt whiskies has earned her the rare rank of Master Blender.


Science is crucial to the distiller's art. One has to know how to measure the "physical parameters" of the whisky—hydrometers to determine the percentage of alcohol, pH meters to test acidity. And then there are the more elaborate modern technologies of analytical chemistry, such as "gas chromatography" and "high-performance liquid chromatography," which Ms. Barrie said can map the chemical makeup of malts thoroughly enough "to provide a 'fingerprint' of our whiskies for quality and authenticity purposes."


Yet trying to understand Scotch whisky with a gas chromatograph is like trying to plumb the mysteries of consciousness with an fMRI brain scan: interesting—even helpful—but woefully insufficient. Whiskies from the island of Islay are known for being briny—the distilleries are all but in the sea—but lab instruments can't nail down that oceanic quality. When it comes to assessing the interaction of hundreds of "aroma compounds" that shape how we taste, said Ms. Barrie, "the most sophisticated measurement tool remains the human nose." Taste buds are a clumsy substitute and would never survive the gantlet of casks that must be gotten through every week.


It was Ms. Barrie's nose that sniffed out a new career. With a degree in chemistry from the University of Edinburgh, she landed a gig testing the chemical makeup of Newcastle Brown Ale. In 1991, she won an internship at the Scotch Whisky Research Institute on the strength of her ability to identify scents. "Part of the interview was nosing 20 little bottles," Ms. Barrie recalled. "I had to detect, recognize and describe" the various aromas, which included classic scotch overtones ranging from phenol, birch tar and camphor to eucalyptus, lavender and juniper. Before acing that test, she had never realized that she had an extraordinary sense of smell.


After an apprenticeship at the whisky institute, Ms. Barrie eventually landed at the famed whisky maker Glenmorangie. There she rose to become Whisky Creator and Master Blender, in charge of the company's flagship Highland single malt, as well as Ardbeg, a whisky made on the peaty island of Islay. (Her special Ardbeg "Corryvreckan" bottling was named by Whisky magazine in 2010 as the "World's Best Single Malt Whisky.") Early this year she moved to Morrison Bowmore Distillers, where she is in charge of making whiskies from the company's distilleries: Bowmore on Islay, Auchentoshan outside of Glasgow and Glen Garioch, near where she grew up in Aberdeenshire.


Many factors go into creating a single-malt whisky—the shape of the still, the barley used, how it is malted. Put it in a cask that previously held bourbon and you'll get a result very different from aging it in sherry-soaked oak. But even with barrels of the same sort, there are differences. The endless variations provide the Whisky Creator with a palette of aromas and tastes to combine.


As Master Blender, Ms. Barrie keeps a notebook in which she jots down descriptions of every barrel that she samples, notes that she then enters into a computer database. When it comes time to bottle—whether the house's standard version or a special variation—she uses that database to recall the casks she will need to combine for the balance she's after.


When creating a special small-batch bottling, Ms. Barrie doesn't think of the whisky in terms of scent or taste. "Usually I look for a sense of place." She imagines where a whisky might be enjoyed, who would be drinking it and then strives to make a pour right for that moment. To make a fresh 10-year-old version of Bowmore, she pictured a little sailboat bobbing off the coast of Islay, helmed by a weekend sailor wet from drizzle and choppy swells. He gets to shore as the sun breaks through the clouds. In that moment of clashing seasons he debates whether to have a tot of whisky or a pistachio ice-cream cone. How would the perfect whisky for that moment taste? It won't be the same as the whisky you would want for the fireside after shoveling a heavy, wet snow, or the whisky right for drinking under Chinese lanterns after dessert at a summer garden wedding.


But on rare occasions, the whisky will make itself. For all the moving of barrels and blending of casks to create spirits for the tableaus she envisions, perhaps the greatest skill is knowing when to leave a whisky alone. Ms. Barrie has sampled more than 100,000 casks, and among them she has found "several" extraordinary ones. "Recently, I nosed a stunning Bowmore cask from the early 1960s," she said. "The exotic fruits of mango and papaya were simply remarkable alongside rich, dark fruits, camphor and wisps of peat smoke."


Blustery seashore or cozy fireside, that sounds fine.