Following up on last week's bourbon primer, we're going to shift our eyes and livers one step to the south this week, and look at bourbon's delicious and popular cousin: Tennessee whiskey.

The best known of the Volunteer State hooches is a brand that is also the best-selling whiskey in the world: Jack Daniel's. The state produces three other, somewhat lesser-known, whiskeys as well, though: George Dickel, Collier and McKeel, and Prichard's.

First, though, what is Tennessee whiskey, and what distinguishes it from bourbon?

He Guided Me to Tennessee

Unlike bourbon, gin, vodka, and other classes of liquor, Tennessee whiskey has no current legal definition in the Federal government's Standards of Identity for Distilled Spirits. The North American Free Trade Agreement offers the only current Federally recognized definition of Tennessee whiskey: "a straight Bourbon Whiskey authorized to be produced only in the State of Tennessee." That's not very helpful.

Generally speaking, Tennessee whiskey is nearly identical to bourbon. (But note the word nearly; I'll discuss the one major difference shortly.) Tennessee is a sour mash product, made mostly from corn, with a mix of other grains that includes wheat, rye, and malted barley. The grains are ground, mixed with water, and fermented in a method similar to that of bourbon. The fermented liquid is distilled in a column still (in most cases; I'll discuss exceptions below), before being aged in new, charred-oak barrels.

Between distillation and aging, though, comes an additional step, one that distinguishes Tennessee whiskey from bourbon. The additional step is charcoal filtering, also known as the Lincoln County Process.

Lincoln County

In the Lincoln County Process, a distillery first takes timbers of sugar maple and burns them to make charcoal chips. Jack Daniel's goes so far as to soak the sugar maple with 140 proof Jack (70% alcohol by volume, or ABV) before burning it.

The new-make (or white dog) whiskey is filtered through a tall vat of maple charcoal chips prior to aging. The vat can be as large as 10 feet tall and 3 feet wide. The whiskey filters through this vat from top to bottom before it's aged. The charcoal is said to mellow out the flavor of the whiskey, smoothing its rough edges, and resulting in a softer, drier liquor.

(Some bourbons, incidentally, are charcoal filtered, but bourbon filtering happens after aging, to remove fatty acids and impurities that might cloud the bourbon; a "charcoal-filtered" bourbon, therefore, is not similar in its final character to a Tennessee whiskey made in the Lincoln County style.)

Only three of the four Tennessee whiskeys use this process: Jack, George Dickel, and Collier & McKeel. Pritchard's is the exception. (The other major difference between Prichard's and other Tennessees is that Prichard's is distilled entirely in pot stills, not in columns.)

Why the name? In last week's history of bourbon, we saw how the boundaries of Kentucky's counties were drawn and redrawn over time; Tennessee's county boundaries have been also redrawn a number of times in the state's history. When the Jack Daniel's Distillery was established, it fell within the then-current boundaries of Lincoln County, before the boundaries shifted, and Jack found itself in Moore County. So although the distillery now resides in another county, the name of Lincoln County is still associated with the filtration process.

Jack Daniel's and the Proof Controversy

Today, Jack Daniel's Black Label is bottled at 80 proof (40% ABV), but it wasn't always so. Until 1987, Jack was sold at 90 proof, before being lowered to 86. Black Label was lowered again in 2004, to the current level, 80 proof.

Why does the proof level make a difference? In brief, it goes like this: According to a 2004 USA Today article about the brouhaha, Jack comes out of the barrel at approximately 125 proof. (Levels vary slightly from barrel to barrel, thanks to the vagaries of aging.) How do you get a spirit to its bottling proof? Dilute it with water. Jack Daniel's at 80 proof has more water in the bottle than does Jack at 86, which has more water than Jack at 90. It's that simple.

The folks at Jack Daniel's say that its marketing research clearly showed consumers expressing a preference for a lower-proof product, and I have no doubt that's so, but the decision has left more hardcore fans, like Frank Kelly Rich from Modern Drunkard magazine, less than pleased.

Eight years on, I think the 86 proof Jack is probably extinct for now, alas, but who knows. The whiskey industry has seen brands resurrected; other brands, such as Four Roses, have come roaring back from decades of mediocrity. This shows that a return to a higher-proof Jack is hardly the most surprising thing that could happen, so let's keep hoping.

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