By Richard Thomas
Bourbon and scotch are arguably the two most famous styles of whiskey. Irish whiskey has its niche, of course, as do non-bourbon American whiskeys like rye. Yet the two big contenders are whiskey’s Kentucky gentleman and its Scotland laird, and that simple fact leads to inevitable comparisons. The ill-informed unfortunately come away with the idea that scotch is intrinsically superior to bourbon, based upon a poor understanding of how scotch (and whiskey in general) is made.
I grew up on straight bourbon whiskey, but now I live in Europe, where small batch and single barrel bourbon is scarce and scandalously overpriced. Necessity and my whiskey-loving nature drove me into the welcoming arms of scotch. The two styles have their own distinctive features, and while I have my preferences, the matter isn’t as simple as one being better than the other.
The two whiskeys use very different grain recipes, and that speaks to the core differences between them. The American term “mashbill” is irrelevant to single malt scotch, since it uses only malted barley. Even the smoky character of the two whiskeys are different. Bourbon draws its smoke from the charred surface of the barrel, whereas the smoke in scotch is drawn largely from the peat burned in the barley malting process. These two different, yet similar flavors underline the relationship between the two whiskey styles (and keep in mind that not all scotches have a peaty flavor in the first place!). I think of it as comparing apples to pears – similar, but not similar enough that one can be declared objectively better than the other.
The single largest misconception in comparing bourbon to scotch is that scotch is somehow superior because generation-long aging periods are a fixture of the scotch industry. A quick glance at virtually any liquor store shelves reveals many scotch labels aged 12, 15, 18 or even 25 years, while bourbon is usually in the six to nine year range.
This misunderstands a critical element in the aging process, namely the relative climates of Kentucky and Scotland. If you are in Glasgow, summer temperatures average a modest 66 F (19 C), but on the other side of the globe in steamy Kentucky that average daily high is 86 F (30 C). The hotter weather accelerates the aging process to some extent, but it is too simple to say that whiskey ages more quickly in Kentucky than in Scotland. As any true student of whiskey knows, simply moving the barrels around the warehouse during the aging process can have a significant effect on the final product, and the substantial differences in climate between the two regions greatly alter the very character of their respective aging processes.
Kentucky’s hotter climate also means more of the whiskey evaporates away as “the angel’s share” than is the case in Caledonia, so aging a barrel of whiskey in Kentucky for 25 years produces far less whiskey than would be the case in Scotland, and therefore a more rarefied product.
Another aging aspect the comparison misunderstands is what kind of barrels are used to age Scottish and American whiskey. All bourbon is aged in new oak, whereas almost all scotch is aged in used oak. The only time bourbon-making ever makes use of an old barrel is for finishing, a practice borrowed from scotch-making. New oak contributes a lot to the color and flavor of a whiskey, but the longer you leave whiskey in new oak, the more likely it is to develop an undesirable astringency. This is less of a problem for the used barrels put to work in scotch-making, since some of those chemical interactions were spent during the barrel’s first run.
By law, all bourbon whiskey must be aged in new charred oak barrels. Scotch must be aged in oak barrels, but any sort of oak barrel can be used. This variety is part of a tradition of creative experimentation in using sherry casks, beer barrels and even old bourbon barrels to age scotch. It has also give rise to the practice of finishing scotch in secondary barrels, a step that has only recently caught on with bourbon-makers.
This ability to choose among aging vessels contributes to scotch as a whole having a wider variety of flavors, whereas bourbon tends to operate within a set group of characteristics. The variability of how scotch is aged makes for a more interesting storyline, but whether it is an advantage depends entirely on whether how you feel the finished product.
Whiskey vs. Whisky
The Whiskey Reviewer has already tackled this semantic issue, and spelling has no real bearing on the character of either spirit.
Bourbon and scotch each come with their own distinctive identities, and those identities are what have made these two separate spirits the world’s leading styles of whiskey-making. One might prefer scotch over bourbon (or visa versa) because of those characteristics, but that is a matter of personal preference rather than absolute superiority.