Bourbon Chemistry

Last weekend I paid a visit to the Maker’s Mark distillery outside of Loretto, Kentucky. The tour of the distillery was fascinating, as they not only showed off their entire manufacturing facility (which is surprisingly small), but they also described the process in detail, including its chemistry!

The Maker’s mash, which they actually allow you to taste by dipping your finger into a fermenting vat, is 70% corn, 16% wheat, and 14% barley. Like other distilleries, Maker’s mixes a little bit of used mash in with the new stuff, to create a “sour mash” and ensure equal pH across batches. Yeast is added that converts the sugars in the mash into alcohol and carbon dioxide, which you can actually see evolving off the top of the liquid. The liquid mash spends three days in a massive vat made of cypress wood, some of which are over one hundred years old! Also, FYI, from personal experience…the fermenting mash is delicious.

After three days, the mash reaches 8-10% alcohol by volume, at which point it’s aptly called “distiller’s beer.” A double distillation process brings the alcoholic liquid up to 130 proof (65% ABV). Maker’s actually markets this stuff as unaged “Maker’s White”—the aging process introduces the familiar brown color and oaky flavor. Unaged bourbon is basically corn whiskey or moonshine.

The oak barrels used to age the whiskey are aged themselves for nine months in order to allow the tannic acid present in the wood to seep out. Maker’s uniquely rotates their barrels within the warehouse, so that alcohol spends about three years at the top and three years at the bottom. However, bourbon aging is not an exact science, as differences in the wood and alcohol can result in different “times to maturity.” Maker’s ages anywhere from five years, nine months to six years, three months.

Maker’s has a semi-automated bottling line; however, every bottle is hand-dipped in sealing wax before being shipped off. Workers dip roughly one bottle every three seconds, but rotate off the dipping line every thirty minutes. In the gift shop, visitors can dip their own bottles.

I honestly thought I was going to be bored out of my mind during this trip, but it turned out great. Highly recommended to any chemists interested in food chemistry out there!

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