Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=218148
Story Retrieval Date: 2/28/2015 11:28:03 AM CST
The pungent aroma of spicy cinnamon and yeasty grains that hangs in the air of North Shore Distillery in Lake Bluff signals that Derek Kassebaum is in the midst of an experiment.
A chemical engineer by trade, he uses basic scientific principles to create the distillery’s unique spirits.
“He’s like a mad scientist mixing together his secret formulas,” said Sonja Kassebaum, Derek’s wife and business partner.
While the precise amount of spices used to flavor North Shore’s vodkas, gins and absinthes remains tightly under wraps, the process by which alcohol is produced is hardly a secret.
“It all starts with fermentation, which is how we get the alcohol,” Sonja said.
One of the oldest known chemical processes, a fermentation reaction breaks down sugar into ethyl alcohol and carbon dioxide in an oxygen-free environment.
The process takes place in sealed barrels. The Kassebaums use locally grown grains as the source of sugar. Yeast is added to the barrels to eat away at the grain until only alcohol, gas and water remain.
“At the end of this process you have the basis of beer,” Sonja said. “The alcohol is at a very low concentration at this point, so you want to remove the water to raise the proof.”
Distillation achieves this goal.
“All we’re really doing is separating liquids with different boiling points,” said Derek, who has run North Shore Distillery since 2004.
While water boils at 100 degrees Celsius, alcohol boils at a significantly lower 78 degrees Celsius. By heating the fermented mixture slowly, alcohol will become a gas while water remains a liquid.
North Shore’s still, nicknamed "Ethel" after ethyl alcohol, facilitates this process.
“Ethel’s head is this shape for a very particular reason,” Derek said. “There’s an expansion of space that is far from the heat source. The water that’s in the vapors has the chance to cool down, turn back into a liquid and drop back down into the kettle. [This allows] us to refine the [alcohol] vapors coming out.”
The result is purified alcohol that has increased from 30 to 90 proof.
Though having a single still limits the amount of liquor they can produce, Derek and Sonja are happy with their small-scale operation.
“It gives us the opportunity to work with a lot of different things to see how they’ll behave in our spirits,” Sonja said. “It’s part of that constant experimentation and getting to explore new things that keeps it fun for us.”