I had to restrain myself – many times – while writing my last post about the Jim Beam distillery. I kept veering off into technical definitions of Bourbon so I could lay them against equally technical descriptions of Scotch and thereby highlight the differences between the spiritual cousins. It would have derailed the post and been an injustice to Jim Beam.
But I realized I needed to write about this topic, especially since my aim in going to the Kentucky Bourbon Trail was to compare America’s spirit against Scotland’s and highlight the differences for the whisky fans among my readers.
I hope this will prove to be a useful reference for the rest of my series on the Kentucky Bourbon Trail. So here it is, a brief guide to the differences between Scotch and Bourbon gleaned from my visits to distilleries at home and abroad.
Whiskies are liquors made from cereal grains, which is a pretty large category. Barley, corn, oats, wheat, rye, sorghum, millet, and triticale all fit the bill. Both Scotch and Bourbon use water and yeast, but the primary difference between the two spirits is their choice of grains.
Bourbon is made with at least 51% corn, though many distilleries use up to 75% corn in their Bourbons. Corn imparts that Bourbon sweetness people seem to love or hate. The other 49% of the mash bill can be made of whatever grains the distillery wants to use, though rye, malted barley, and wheat usually make up the difference. Across the Kentucky Bourbon Trail, distilleries used a second grain, either wheat or rye, which they called the flavoring grain, to make up the second biggest percentage. In general, malted barley composed 10% of a mash bill to “round off the flavors” as some guides told me. Rye typically imparts a spicier, less sweet element to whiskey while wheat yields a sweet, inoffensive smoothness.
Scotch is made with malted barley, to which other whole grains may be added. Single malt whisky, arguably the most popular type of Scotch whisky, is made with 100% malted barley. Blended Scotch can have other grain spirits added to it, often referred to as neutral grain spirits, but there are still two separate distillations happening: one for the malt whisky and one for the neutral grain spirits. These two distillations are then blended together; there are no mash bills in Scotland. Malted barley yields smooth, complex flavors in the final product.
Both Scotch and Bourbon have some interesting laws surrounding the strengths of their spirits. I don’t know the backstories on how these proofs were chosen, but I’m willing to bet these were some of the most divisive topics between distillers and their respective governments. After all, the higher the proof the more alcohol in the bottle, and alcohol is truly what is being bought, sold, and taxed here.
Scotch cannot be distilled to more than 94.8% alcohol by volume, not that you could get a much higher ceiling. That said, in my experience, most Scottish distilleries are cutting their newmake spirit between 120 and 150 proof. On the other end, Scotch cannot be called Scotch once the ABV drops below 40% (80 proof). This is one of the parameters that makes aging Scotch for a very long time difficult. Alcohol evaporates every year and many distillers have to cut short maturation because a given cask is hovering at 40.1% ABV after a few decades in the warehouse.
Bourbon, on the other hand, cannot be distilled to more than 80% ABV (160 proof). Interestingly, there’s a unique proof law that states Bourbon cannot be entered into barrels at higher than 62.5% ABV (125 proof). Finally, like Scotch, Bourbon must be bottled at no lower than 40% ABV (80 proof).
Generally, the proofs don’t mean much for the flavor of the whiskies, though they are the primary data point for calculating speed to drunkenness and severity of hangover. Scottish distillers have a lot more freedom with their proofs, but distillers might tell you it doesn’t mean much for them. There are impurities in the spirit at too high and too low ABV. The heart cut, that sweet spot chosen by each master distiller, is where the purest flavors live.
The second most important difference between Scotch and Bourbon resides in how the two spirits are matured.
Scotch must mature in oak casks in Scotland for a minimum of three years. These oak casks must not exceed 700 liters and must age in excise warehouses. Furthermore, laws recently changed such that Scotch must also be bottled in Scotland. Previously, distillers could sell casks to buyers outside Scotland. This allowed buyers to continue aging the spirit in its cask after sale and potentially sell it again, later on, for heaps more profit.
Bourbon must mature in charred, new oak barrels, and age for at least two years.
On the face of it, these requirements might seem random, but temperature and wood play important roles in these laws. Kentucky experiences broad temperature fluctuations – hot summers, cold winters – and this has a huge impact on the “aging” of whiskey in barrels. As temperatures change, barrels contract and expand, releasing more of the angel’s share and speeding up the process of flavoring the spirit, whereby the wood absorbs and expels the liquor. Since they must use charred, new oak barrels, too, there are loads of flavors coming off the wood. You can have a nice Bourbon in a fraction of the time it takes to get a nice Scotch.
In Scotland, temperatures are consistently cool all year long. Rarely do they have heat waves or bone chilling cold. So the barrels work much more slowly on the whisky inside their staves. Additionally, Scottish distilleries primarily use oak barrels that have been used to age another alcoholic beverage previously, such as Bourbon, Sherry, Port, wines, beer, and Scotch. Used barrels have lost some of their original wood flavor and gained others, and distilleries in Scotland use barrels over and over again (sometimes as many as five times!). It takes longer to bring out the flavors in the wood with each successive use of the barrel.
This might seem obvious, but you can’t make whisky outside of Scotland and call it Scotch (though the Japanese have tried). Whisky can only be called Scotch if it follows the previous rules and is made and aged in Scotland. Other countries make whisky with the exact same ingredients and methods, but they are forced to use the much less prestigious term “malt whisky.”
Bourbon…well, now this is interesting. Many people believe Bourbon can only come from Kentucky. That is wrong. Bourbon must be made in the United States of America, but it can be made anywhere within the country (so long as all the other rules are followed). Bourbon’s name derives from Bourbon country in Kentucky, but the manufacture of Bourbon isn’t relegated to this region by law. In other words, you can drink Texas Bourbon or Wisconsin Bourbon and that would be legal and right.
The Bottom Line
Whew, that was a lot of minutiae. Does it make sense to you? Contradict what you’ve always known? Support it?
Knowing all this information, the best way to ferret out the differences between Scotch and Bourbon is really simple. Taste it. I think you’ll pick up on the differences pretty quick.