How Do You Define Terroir in Whiskey?

Does the taste of rye whiskey differ based on where the rye it's made from is grown? Bryce T. Bauer on the Pennsylvania distillery that's trying to find the answer.

Is rye, rye?

That’s not some existential koan (well, maybe it is). But for Pittsburgh-based Wigle Whiskey, this question has been the inspiration for an ongoing, back-of-the-barrelhouse science project to explore whether rye grain has, like the wine grapes of the world, terroir. In other words: Does rye whiskey taste different depending on where the rye it’s made with is grown?

To get to the bottom of this, Wigle put the first batch of rye for the project into barrels a little over a year ago. Today, they have rye from farms in seven different places aging in their barrelhouse—two from Pennsylvania and one each from New York, Ohio, Minnesota, Saskatchewan province in Canada and the Whistle Pig distillery in Vermont.

The question is of particular interest to David Harries, the distiller leading the project, because Wigle’s distillery is located in Pennsylvania’s Monongahela Valley, an area that was famous for its rye whiskey during America’s early years. In fact, at the time, the rye was so popular it was often known simply as “Monongahela.”

“We wanted to see if there was any credence to the idea that Pittsburgh, or the area around us, produces rye grain that in turn produces superior rye whiskey,” says Harries.

The idea of terroir-based spirits is nothing new: Scotch must come from Scotland, after all, and bourbon must come from America, to say nothing of spirits such as Calvados, rhum agricole and the agave spirits, which fall under even more stringent place-of-origin controls. But what people mean when they say “terroir” isn’t always the same. Sometimes it’s used to refer strictly to the how the land and climate of a certain place effects the ingredients grown there. But for many products, it can also refer to the human element of how tradition and culture dictate the way something is made and the style that’s considered authentic.

What has traditionally set many American whiskies apart from the aforementioned spirits, as well as the grapes that go into wine, is that the grain used is rarely grown by the distiller or even sourced from the surrounding region. Instead, whiskey grain tends to be purchased as a commodity on the open market, which means that its terroir is, effectively, everywhere.

Harries, who studied chemistry in college, said that the distillery is attempting to control as many variables as possible in this project to truly understand this potential aspect of whiskey terroir—from the distilling and fermentation techniques to aging the spirits in 23-gallon barrels made by the same cooperage. That said, there are limitations to working within a small distillery.

It’s just not possible to control everything to the level of precision needed for, say, an academic study. Subtle differences, such as where barrels are positioned for aging, or the fact that the distillery’s method of measuring by volume can only so precisely determine the amount of grain that goes into the mash, may have some impact on the whiskey’s flavor. And then there’s the rye itself: Farmers in the each of the areas tend to grow different varieties of rye based on what’s best-suited to their individual environment. Other variations in the fermenting and distilling process—essentially inevitable in a craft distillery—have caused proof of the various runs to also vary by a few points, which means that the liquids vary before they’re even in the barrel.

Despite all of the variables, by asking the question of whether grain from different regions impacts flavor, Harries and the folks at Wigle are entering an area that’s seen very little public research.

One of the few scientists who have studied the provenance of aroma and flavor in spirits is Tom Collins (yes, almost too good to be true), a chemist and professor in Washington State University’s viticulture and enology program. To determine how significantly the grains in the mash bill influence the aroma of rye and bourbon whiskey, Collins and his colleagues assembled a set of ten whiskeys, half ryes and half bourbons, from five major distilleries. They asked a panel of non-professional evaluators (students, faculty, residents from the University of California, Davis community) to nose each whiskey and sort them into groups based on similarity. What they discovered was that the strongest correlation the panel found between whiskies was the producer, followed by age and proof.

“With this particular set of whiskies and this set of panelists, the mash bill was not the main difference that the panel found,” Collins said. He emphasized, however, that the study was just an early one. Panelists, after all, only assessed based on aroma, they didn’t actually drink the whiskies.

To scientifically assess the differences in the whiskies Wigle is producing, Harries has been analyzing the composition of the grain as well as that of the whiskey straight off the still (he’ll also do periodic tastings as it ages). With regards to the grain itself, those tests showed differences in such things as protein and starch content, as well as mineral levels, in the rye from various places. And in tests of the new “make” (i.e. the spirit fresh out of the still) he found that there were there were existing differences in the chemical make-up of the whiskies before they went into barrel.

In my own assessment of a number of barrel samples Wigle sent along, I noticed that there were clear differences between the Vermont and Canadian ryes. While both had seen less than a year in oak and tasted quite young, the Vermont rye was fruitier with caramel notes, while the Canadian rye was fuller and spicier, with aggressive petroleum aromas. Both, quite obviously, needed more time in barrel.

Whether these differences can be attributed to ryes of different origins versus differences in the barrel, the proof, the grain bill or even the position of the respective barrels in the distillery is impossible to know.

Thankfully, more insight to those questions should be coming. Collins has more research planned, and Harries wants to keep expanding the rye terrior project by distilling grain from more regions. Meanwhile, those initial batches continue to age and should be ready for public release starting in a little over six months. No matter the results, Wigle’s identity is so resolutely tied to Pittsburgh and a commitment to sourcing local grain. In this, they are, perhaps, reaching toward yet another aspect of terroir—that of unwavering loyalty to a place.