HMNS Beyond Bones Podcast · Houston Museum of Natural Science

The Science & History of Bourbon

·54 min·4 clips

Find out how used bourbon barrels are shipped to Scotland to age scotch whisky.

Johnny Hemberger hosts this episode with Randy Bruner, a bourbon expert from the HMNS Sugar Land location. They explore the intricate science and rich history behind America's native spirit. The conversation delves into the specific geographic, geological, and historical factors that shaped bourbon's identity. Bourbon must be made in the United States, with 95% of it produced in Kentucky due to the state's unique limestone-filtered water and four-season climate. The spirit's legal definition requires it to be made from at least 51% corn, aged in new, charred oak containers, and distilled to no more than 160 proof. Randy explains that the primary "flavor grains" besides corn are typically rye or wheat, with malted barley added for its starch-converting enzyme, amylase. The fermentation process takes three to five days, while distillation in column and pot stills is a matter of hours. The iconic amber color comes solely from the charred oak barrel, which imparts caramelized sugars and flavors as the spirit expands and contracts with temperature changes. A used bourbon barrel can only be employed once for bourbon but is often shipped to Scotland for aging Scotch. The aging process involves about 300 different compounds interacting within the barrel, and barrels lose about 6% of their volume in the first year and 3% annually thereafter. Professional tasters and blenders, often younger women for their acute senses, work to maintain consistent flavor profiles by blending hundreds of barrels. Surprisingly, the location of a barrel in the rickhouse significantly impacts the final product, with barrels at the top aging faster and stronger due to heat. Maker's Mark is unique in rotating its barrels to achieve uniform aging. While some seek rare pre-Prohibition bottles, the liquid inside does not continue to age once bottled, making its historical production methods part of its allure. During Prohibition, six Kentucky distilleries were permitted to remain operational to produce bourbon for medicinal purposes. The tone is conversational and educational, seamlessly weaving together chemistry, history, and industry anecdotes. The style is accessible, with the host asking layperson questions that guide the expert through complex topics. This episode is perfect for history buffs, science enthusiasts, or anyone curious about the craftsmanship behind their favorite drink. Listeners seeking a fast-paced narrative or those with no interest in spirits might choose to skip it.

As heard by us

A patient bourbon talk that turns geology, aging, and proof into something easy to picture.

Bourbon is framed as a meeting point of science, history, and place. Kentucky limestone, low-iron water, barrel aging, proof shifts, and the industry's long arc are threaded into one steady conversation.

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Why you'd press play

If you want bourbon explained from limestone to rickhouse, start here.

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