All bourbons are grain spirits. Maker's starts from a blend of 70% corn, 16% red winter wheat, and 14% malted barley. (Bourbons range in their corn content from 60–86%, and malted barley from 5–14%.) Most use rye, according to distillery education director Dave Pudlo, with fewer making use of red winter wheat. The grain mixture used to produce bourbon is known as the "mash bill."
"You need corn because it's high in starch, and those starches break down into sugars," says Pudlo. "But it's bland. You need salt, pepper, and butter to flavor it up. Except in our case, our 'salt, pepper, and butter' are red winter wheat, barley, and Samuels yeast"—the strain of yeast used by the family distillery for generations.
Here Comes the Corn
All the grains are delivered in trucks, and their contents are put through an initial inspection. A long metal tube called a "grain thief" (what a fantastic name) sucks up samples at random spots throughout, and deep into, the grain load; "Farmers who want to get rid of their bad corn would put it all at the bottom," says Pudlo, "so we have to get deep in there."
Grain All Good?
These samples are visually scanned to ensure they are indeed mostly grain, without excess scraps of organic material. Then they're tested for moisture content (which should be below 14%, to protect from mold and mildew). A sample of corn is ground finely, hydrated, and then tested for the presence of genetically modified corn or herbicides ("We've got to test because of cross-pollination and cross-contamination; a farmer might not know if this is showing up in his corn," says Pudlo). Finally, the grains are ground finely, microwaved with water, and given a simple "smell test" from which the lab technician can sense many irregularities. Maker's averages around a 7% grain rejection rate, says Pudlo.
Shake 'em Up
The grains are agitated to clean them further, separating out twigs and such from the grains themselves, while a vacuum system sucks up and removes lighter particles. "These stalks are fermentable," said Pudlo, showing us short fibrous bits sorted out from the corn. "If they get in the mix, they'd alter everything."
These three grains then go through the roller mill press, which squeezes the grains out of their husks—keeping the core grain intact without also grinding up the bitter husk. (Other methods can actually pulverize the husk as well, says Pudlo; "Think of the husk like the orange peel, when you're making orange juice. You want to squeeze the orange for the sweet juice—you don't want to toss it in a blender, and grind the peel up in there as well.")
There's one more element: the yeast, which Maker's grows from a strain the family has used continuously for generations. Tasted alone, the yeast solution that starts every batch tastes something like a Belgian ale: a little yeasty, a lot sour, with a refreshing acidity and a scent that's all bread and bananas.
After it's grown and allowed to multiply for three days, it's lost that gentle yeasty smell and, as I learned when unwisely sticking my head in a vat, is a knockout sour-savory punch to the sinuses. (By knockout punch, I mean "I went reeling backward and almost fell off the narrow platform.")
Next comes the cooking process: when the different elements are first combined. Corn is full of crystalline starch, which yeast can't digest, so the corn, some pre-malt, and the water are first cooked extensively, boiled and then brought down to 161°F for three hours, to break the starches down. The red winter wheat is then added at that temperature (it can't go higher, or else the proteins would break down in the wheat shell, which they don't want); it's cooked for ten minutes, then dropped to 151°F and the malted barley is added.
(The water is actually boiled with hops, before it's used—they lend a preservative capacity and keep strains of yeast that aren't the desired ones from taking root in the mash bill.)
As this all churns, the rich, steamy smells in the distillery evolve, from sweet corn to malty barley.
Then: alcohol time! Here's where mashed-up grain first turns into booze. Yeast and mash bill meet in these cypress tanks, where they hang out for three days, as the yeast eats up the sugar and turns it to alcohol.
In the Tanks
Right when it lands in the tank, the taste is all sweet corn, like ground-up sweet cornbread or even breakfast cereal. After a day, it's a little more like bread dough. On day 3, its last, the taste is much closer to an Belgian ale: a little sour, a lot yeasty, and much less sweet. At this point, it's about 7–8% alcohol.
Temperature determines how fast the yeast work; in the winter, on our visit, the room was kept at a balmy 80°F.
The fermented mash then goes through distillation, to turn into the much boozier spirit that eventually becomes Maker's. It's pumped into the top of the "column still," a several-story vertical cylinder cut by a series of horizontal plates, with steam rising up from the bottom. Since alcohol boils at a lower temperature than water does, that alcohol evaporates and rises to the top (where it's then captured), while the progressively less alcoholic mash is brought down to the bottom and then discarded.
It then goes through a second distillation, after which point it's a clear, 130-proof spirit.
Where It All Happens
Everything from grain to spirit takes place in this one building.
Each shipment is examined for potential defects: chips in the wood, seams that might leak, anything that would compromise the integrity of the barrel for its 5+ years of aging.
The barrels are made of new oak, and that wood has been dried outside for at least eight months (and at least one full summer), allowing the bitter sap and tannic acids to dry out. They're then charred at 1200°F for 40 seconds, giving them the precise char Maker's wants, before they're delivered to the distillery. (Pudlo refers to the coopers as "wood chefs," as their composition affects the eventual taste of the bourbon so much.)
Each barrel is filled to capacity…
… And Sealed
and a walnut bung is pounded in to seal.
Rotating the Barrels
Each barrel is then stored in the warehouse for upwards of four years (there's no pre-determined amount of time, as conditions always vary; each barrel is pulled when, according to a panel of tasters, its taste is in line with Maker's standards).
There's as much as a 20–25°F difference in temperature between the warm top of the room, and the much cooler bottom. Each barrel spends its first three summers toward the top of the warehouse, where the wood of the barrel "breathes" and the alcohol is forced into the wood's pores—helping along the process of imparting flavor to the bourbon. The bourbon penetrates around halfway into the wood. "At this point," says master distiller Greg Davis, "if you tasted it then, you've got that spike of wood on the palate, but then it finishes flat and thin."
Later in its aging process, it's brought down to cooler temperatures at the bottom of the warehouse, where the flavors marry and concentrate.
Two different methods ensure consistent quality: a tasting panel, and the Maker's Mark lab.
A team of 15 to 17 Maker's Mark employees carries out an extensive blind tasting every day—but never know exactly what they're tasting. Each sample is assessed via "triangle test," in which tasters comment on three samples, two identical and one different, without ever being told which is which—showing the person analyzing the results whether the taster is consistent.
That tasting is backed up by chemical analysis—gas chromatographs that identify the incidence of major taste compounds; mass spectrometers that do the same.
The File Cabinet
Samples are kept of every bottling from years past, allowing any reported problem or defect to be checked against an original sample.
And Into the Bottle
All that before it's pumped into bottles and hand-dipped into red wax for Maker's signature seal. (Yes, really. But more on that in a future article.)