Diminishing Terroir

So a couple of years ago, during an impromptu Cognac tasting that I put together while on a river cruise in Bordeaux, I was asked the following question by the Director of the American Wine Society, “Does terroir in spirits end with distillation?” My initial answer, with minimal thought, was yes and no. To me, distillation captures the congeners created during the fermentation stage. If a spirit is bottled following distillation, then the terroir does end. For barrel-aged spirits, the majority of which utilize oak, I would say no, because the wood for the casks is entirely terroir, and will yield different characteristics depending upon the type of oak.

American Oak is primarily sourced from the Ozarks and the Appalachian mountain chains, both of which offer a rich source of flavorful extract via their hemicellulose layer, or the “Red Layer” that is formed in a new charred barrel.  This layer is composed of many different sugars with lower molecular weights than those found in cellulose, which accounts for its easy solubility in alcohol.  The char level will determine how much flavor and aroma is extracted, with a Level 4 Char yielding more than a Level 3 Char.  Common flavors such as caramel and vanilla are due to the Red Layer, along with some spices.  American Oak also offers high oxidation potential due to the porous nature of the oak, and over time, oxidation can create additional esters.  Each year that a spirit ages in new charred oak barrels, terroir from the grain and yeast diminishes because of the sugars and flavors being extracted from that layer.

Hungarian Oak has become more and more popular for wine and spirits ageing.  The Zemplén forest usually gives the best oak for barrel making.  Because the climate is colder, winters are longer, and the average altitude is higher, the trees grow slower, creating a tighter, less porous grain.  In France, oak from the Limousin and Troncais forests will offer different characteristics to Cognac.  Two varieties of oak were selected because of their special characteristics: Quersus pedunculata and Quersus sessiliflora. Those wood varieties are hard but at the same time flexible.  The Tronçais forest is situated in Allier and provides slightly softer and grained wood. The wood from the Limousin forest is medium grained, a bit harder and even more porous than the Tronçais.  The tannins in Tronçais oak are popular because of their softness – the Limousin oak is more about being strong but balanced.  Apparently, a Cognac will extract more tannins in a Limousin oak barrel.  What’s more, Limousin oak is known for the rich vanilla-like flavor it imparts to eau-de-vie.

                Since that conversation, I’ve seen different articles on terroir and whiskey, but it had me cogitating beyond that.  I think only a fool would say that terroir doesn't exist in spirits or whiskey. Rye grown in Canada, western Pennsylvania, and Germany will yield three different flavor profiles off the still if produced exactly the same.  However, I do feel that a legitimate question is when, and how much does terroir diminish, especially in new charred oak barrels for Bourbon and many American Whiskies.  I've read and heard that between 50% - upwards of 60% of the flavor in a bourbon can come from the barrel.  Personally, I think it sits in the middle, but still depends upon many factors.  Given that, where does terroir from the grain, yeast, etc. start to diminish because of the new charred oak and ageing?  I ponder this while gazing at a label touting Bloody Butcher Corn in their bourbon.  For more insight, I posed this question to Alan Bishop, Master Distiller of Spirits of French Lick, whose motto is “Respect the Grain”. 

As Alan says, “Good Question. I agree, oak itself can impart terroir as you said and I certainly agree. The rest depends on distilling technology, ingredients, and methodology. For example, a pot still is exquisite at expressing terroir, on the other hand in a column still it is minimal. Pot stills in particular do break down long chain fatty acids into esters and phenols, but those are just more refined versions of terroir. Our methodology at Spirits of French Lick is all about a blend and balance. 50% raw material, fermentation, and distillation and 50% maturation. At some point will the terroir diminish with age? Yes, but so will all other positive aspects of a spirit’s character. For Bourbon in a traditional warehouse, I'd say 8 years at the max. But that’s just me.”