Vacuum Distillation: When Gin Goes High-Tech
At first glance, the star of the show at Durham, North Carolina's brand-new Durham Distillery seems to be a custom-designed Mueller still, its copper curves and columns gleaming in the window of the renovated garage the gin distillery now calls home. But peer a little deeper into the back room where the production takes place, and you’ll see an unassuming contraption that does just as much work, but in a very different way. This is the distillery’s Buchi R-220SE Rotavapor, and if it looks like it belongs in a chemistry lab instead of a distillery, that’s because it does.
Used primarily in the pharmaceutical industry to remove solvents from materials in a vacuum, chemists use the Rotavapor to study the resulting compounds that can be used to create drugs. With a background of 18 years as a pharmaceutical chemist, Lee Katrincic is well suited to adapting this technology for a completely novel purpose.
Lee and Melissa Katrincic—a husband-and-wife team who live in Durham—founded Durham Distillery to create “traditional spirits of the new South” by bringing modern science into the age-old realm of distillation. They combine vapor distillation with vacuum distillation to produce—currently—two craft gins: the Conniption American Dry with 44 percent ABV, and the Conniption Navy Strength gin at 57 percent ABV.
“We were looking at how to really bring the art and the science of gin-making together,” Melissa says. “The art is in the balance of the gin, but the science just hasn’t been challenged. Gin is made the way it’s always been made.”
To create their gins, the Katrincics first distill high-quality ethanol through the fully electric copper still, and allow the vapors to blend with botanicals like juniper berries, coriander, and caraway. The vapor distillation is a familiar process, though the Katrincics use a wide tray, rather than a more conventional basket, to hold the botanicals in the pot. This way, all (instead of just some) of the vapors are forced through the botanicals, resulting in an enhanced and more rounded-out flavor.
A three-hour run produces a 200-liter batch of a base gin. The art, as Melissa puts it, is in blending fresh botanical distillates with this base, and the science is in their production.
“Juniper can handle the heat, caraway can handle the heat—it’s just your fresh components like cucumber that can’t,” Melissa says.
For these ingredients, like cucumber, honeysuckle, and fig, the Katrincics turn to the Rotavapor, which allows them to incorporate the flavors in the gin in a new way. Many other distillers rely on extracts, or else distill the sensitive botanicals with vapor or maceration, but the heat of these processes cooks them, resulting in an unpleasant bitterness.
The Katrincics place each of their fresh botanicals individually into the Rotavapor’s flask with ethanol, and then the pressure is lowered to nearly zero. In this vacuum, ethanol distills at room temperature, allowing the botanical flavors to blossom. The vapor from this distillation is collected on a coil cooled to about 41 degrees Fahrenheit, where it condenses and drips into a collection vessel.
“In pharmaceuticals, we are interested in what [remains] in the ‘pot’ of the Rotovapor after the distillation,” Lee says. “At the distillery, we’re interested in the distillate.”
The three botanical distillates are then mixed in careful proportions with the base gin and proofed to create Durham Distillery’s products.
While many distillers are experimenting with vapor distillation, the Katrincics don’t know of any using this type of vacuum technique to create gin in the United States. Because the Rotavapor is being used so unconventionally, they say their application of the pharmaceutical apparatus simply doesn’t occur to many people in the gin industry. Creating gin from both vapor and vacuum distillates is even rarer.
“Vapor distillation lends itself to a softer, more complex spirit, where you can taste many of the nuances of your botanicals that might be lost or muddied in maceration,” says Steven Cage, co-founder of Artisan Still Design and an expert on still design and manufacture. “But the combining of techniques is new,” he says, adding that while vacuum distillation has been around for some time in other industries, it’s an innovative approach to alcohol that’s beginning to gain some traction in a slow-to-change industry.
But the idea of bringing a new face to craft gin distillation—and creating bold and new flavors while they’re at it—is precisely what excites Melissa and Lee.