SciFri Live: Bourbon Science Quiz
16:10 minutes
How much do you know about the science that goes into making bourbon? One would think the citizens of Kentucky — the epicenter of the corn-based whiskey — would know more than the average Joe on the topic.
At a taping of PRI’s Science Friday with Ira Flatow earlier this year at the Brown Theatre in Louisville, two teams composed of local bourbon enthusiasts tried their luck at a few questions connected to the popular hard liquor. The teams’ names reflected two the most popular bourbon-based concoctions: Hot Toddy and Old Fashioned.
“I definitely think people underestimate the amount of science that it takes to make a glass of bourbon,” says Marianne Barnes, the master distiller at Castle & Key Distillery in Frankfort, Kentucky. She was under the spotlight to help provide insight behind the stiff alcohol of choice for many Kentuckians — and well beyond.
Barnes, who is the state’s first woman master distiller, earned a degree in chemical engineering from the University of Louisville before joining the industry.
“I really just kind of got lucky,” she says. “I went to school because I thought I was going to do biodiesel, and then learned that there are a lot more fun things that you can make with corn.”
Castle & Key sits on the site of what is known as the Old Taylor Distillery, which dates back to 1887 when Col. Edmund Haynes Taylor, Jr. founded it. The current distillery, which began in 2014, bases its recipe on a sample of bourbon made in 1917 — two years before the start of Prohibition — that was found in a “dusty old liquor cabinet in a horse farm in the area,” according to Barnes. The original sample and the current version share a genetically similar strain of yeast, she says.
“He had a very special way of making bourbon,” Barnes says of Taylor.
So what is some of the science behind it?
For starters, to be classified as bourbon, the composition of bourbon mash has to be made up of 51 percent corn. Corn’s most important contribution to the fermentation process is the starch that it produces when compared to the other two main grains of the recipe: rye and barley.
“It’s got vastly more starch than the other two grains,” Barnes says, “so it’s the workhorse of your grain recipe. That’s where the enzymes are going to break down to produce sugars, which then the yeast consumes.”
After fermentation, the mash itself later goes through a distillation process in which ethanol — the actual drinking alcohol — is separated from water by heating the now-liquid mash, given that ethanol has a lower boiling point than water.
“So when you think the process of distillation it all has to do with a difference in those two temperatures. So the bottom of the still — whether it’s a pot still or a column still — that’s where you get your hottest temperature,” Barnes says of the devices that are often made of copper.
“So your alcohol and your water are both going to turn into a vapor, but as it moves up in the still, it’s going to lose temperature. It’s going to lose energy. That alcohol will stay in a vapor phase and the water will turn back into a liquid and head out of this still, so you’re condensing your alcohol back into a liquid and that’s when it goes into the barrel.”
And the barrel may be the most important part. Although fellow liquors — like the vodka that Castle & Key makes — can be up to 190 proof in its purest form, bourbon has to be distilled at 160 proof to preserve the flavor that comes from aging in charred oak barrels.
The drink actually gets its vanilla flavoring from the degraded lignins (complex organic polymers that are vital to the building of cell walls) that are found in the charred oak.
“So the wood lignin, if you think about it, it’s like a ligament,” Barnes says. “So this is what holds the cellulose and the hemicellulose of the barrel together. So it’s in the presence of heat and alcohol that you start to break down those lignins into different acids.”
One of those acids is coniferyl acid, which turns into coniferyl aldehyde in the presence of oxygen — then turning into vanillin, an organic compound, which accounts for the vanilla flavor.
Highly skilled workers known as coopers, using oak that is at least 40 years old, meticulously craft the barrels.
“You get basically one barrel per tree and you have to cut it in a very particular way so that the grains lock together when you assemble a barrel so that it doesn’t leak,” Barnes says.
The barrels undergo a process called “seasoning the wood,” which softens the wood and gives bourbon its distinct taste.
The final question posed in the quiz, to provide a smattering of just some of the science being conducted around the liquor of the hour, was as follows:
Which of these is not a real study — fake news, if you will — about bourbon or whiskey?
- The effects of ethanol and bourbon on maze learning and goldfish.
- Heating whiskey and other alcoholic beverages to induce superconductivity in iron-based compounds.
- Using whiskey and ethanol to prevent wound infection in emergency settings.
- The effects of the microgravity of space on bourbon’s maturation.
The answer? No. 3 — in spite of what we may have learned from John Wayne and his counterparts when it comes to makeshift medical care.
“This is the one that I feel like is the most likely, which is hilarious, right?” Barnes says. “Because you see people with their bottle of whiskey in old Westerns.”
Segment Guests
Marianne Barnes
Marianne Barnes is a master distiller at Castle and Key Distillery. She’s based in Frankfort, Kentucky.
Segment Transcript
IRA FLATOW: This is Science Friday. I’m Ira Flatow. Now we’re going to raise a glass and toast the holidays with our bourbon quiz. Earlier this year, we recorded this show at the Brown Theater in Louisville, Kentucky. No conversation there is complete without talking about bourbon. Master distiller Marianne Barnes tested our smarts about the spirit in a quiz. So we’re going to take you to the stage. Play along and see how much you really know about bourbon. Trip to Kentucky would not be complete without talking about?
AUDIENCE: Bourbon.
IRA FLATOW: Oh, you know your stuff here. And we’re not talking rye or whiskey, we’re talking about the corn-based barrel-aged bourbon. And there’s a lot of science, actually, that goes into bourbon, from picking strains of yeast to formulating the right mash, and the process of distillation and aging.
They are all about getting the timing and a temperature right, and we’re going to be talking all about this with my next guest, who is here to help us break down the science. Marianne Barnes is the master distiller at Castle & Key Distillery in Frankfurt. Welcome to Science Friday, Marianne.
MARIANNE BARNES: Thank you so much, Ira.
IRA FLATOW: Now, I understand that you have a degree in chemical engineering.
MARIANNE BARNES: Yes, that’s correct.
IRA FLATOW: Does that make a bourbon better if you know the chemistry about what’s going on in there?
MARIANNE BARNES: I definitely think people underestimate the amount of science that it takes to make a glass of bourbon.
IRA FLATOW: And you’re here to tell us about this. How did you get into this? How do you go from being a chemical engineer to being involved in making bourbon?
MARIANNE BARNES: I really just kind of got lucky. I went to school because I thought I was going to do biodiesel, and then learned that there are a lot more fun things that you can make with corn.
IRA FLATOW: And you are a master distiller, is that right?
MARIANNE BARNES: That’s correct.
IRA FLATOW: And you make the recipes for the bourbon? You help make the recipes?
MARIANNE BARNES: Oh, absolutely.
IRA FLATOW: Wow. So what is the recipe, the basic recipe, for making the bourbon?
MARIANNE BARNES: Well, the regulation states that for bourbon, you have to be at least 51% corn, so the rest of your recipe can be made up of any cereal grain. Folks most often are using rye or wheat and barley.
IRA FLATOW: And so when you work at Castle and Key, how do you make your bourbon distinctive from other bourbons? What’s the secret chemistry in there?
MARIANNE BARNES: The secret chemistry of Castle and Key bourbon is all about history. So Castle and Key Distillery was built in 1887 by Colonel E.H. Taylor, and he had a very special way of making bourbon. In fact, we’ve based our recipe on a sample of bourbon of his that was made in 1917.
So distilled pre-prohibition that had been preserved in the bottle, and we discovered it in the back of a dusty, old liquor cabinet in the horse farm in the area, and actually used that. Did an analysis on it, some GC HPLC, decoded the recipe, found a genetically similar yeast strain, and that’s how we based our recipes.
IRA FLATOW: From a dusty old bottle in the back somewhere?
MARIANNE BARNES: That’s right.
IRA FLATOW: We’re going to get into the more details on our quiz, and you’re going to stick around and help us do that. And all of you, ready to play? Are you ready to play up for this now, audience? Play this [INAUDIBLE]? OK.
We have a couple of teams. We have two brave teams of Louisville Public Radio fans, who are going to ferment over our questions. Get it? And then they get to distill the answers. Oh, oh. And Annie Nero, who is the voice of Science Friday– you might have heard her during our shows– is helping us with the official scorekeeping. Hi, Annie.
ANNIE NERO: Hello, Ira.
IRA FLATOW: Oh, sound of God. OK, tell us what the prizes are.
ANNIE NERO: The winners will get a Science Friday T-shirt, and from Louisville Public Media, you’ll get a T-shirt and two tickets to the upcoming Moth StorySLAM.
IRA FLATOW: Oh.
MARIANNE BARNES: The stakes are high here, folks.
IRA FLATOW: Oh. I want to play, but I can’t. OK, let’s meet our teams. Over here on my right is the team we’re calling Team Hot Toddy over here. Tell us about yourselves. How do you take your bourbon, for example?
TEAM HOT TODDY: I take my bourbon usually with sweet and sour mix, which is, I know, a terrible thing to say right now.
IRA FLATOW: And your partner?
TEAM HOT TODDY: Hi, my name is Allison, and I like my bourbon on the rocks, please.
IRA FLATOW: And our team on the left here, team Old-Fashioned, we’re going to call that team. Welcome, Old-Fashioned to the competition. Tell us who you are and how you like your bourbon.
TEAM OLD-FASHIONED: I am Heather. This is my husband, he’s the sweetness. And I prefer my bourbon to be neat.
IRA FLATOW: Mr. Sweetness?
AUDIENCE: Ironically, old-fashioned is my favorite bourbon drink.
IRA FLATOW: All right, let’s hear it for our teams. We’re going to get ready for the competition. Marianne’s going to judge the answers and tell us which one is the correct one and why it is the correct one. And the questions, as we go along, they’re going to get harder. But the good news is that you get more points. Let’s start out with the first question.
OK, one point, worth one point. By regulation, as you’ve told us before, corn makes up at least 51% of the grain recipe for bourbon. So here is your question. What is corn’s most important contribution to the fermentation process? Is it A, enzymes, B, starch, C, flavor, or D, none of the above. What is the correct answer? You have 15 seconds to think about it. Go.
Corn’s most important contribution to the fermentation process. Hm. The all popular D up there. Everybody [INAUDIBLE] Well, 15 seconds are about up. There’s [? Bueller, ?] the buzzer. OK, what is the correct answer? Let me go to our friends in Hot Toddy. What’s the correct answer?
TEAM HOT TODDY: I believe it’s B, starch.
IRA FLATOW: B, starch. Let’s go over to Old-Fashioneds.
TEAM OLD-FASHIONED: I’ll go with B.
IRA FLATOW: B. Both said B.
MARIANNE BARNES: That is correct.
IRA FLATOW: Starch is the right answer. Tell us why that was the right answer.
MARIANNE BARNES: Yeah so when you think about the composition of a bourbon mash bill, it has to be at least 51% corn. And although it does contribute flavor, it’s most important contribution is the starch. It’s got vastly more starch than the other two grains that you make it up with. So it’s the workhorse of your grain recipe. That is what the enzymes are going to break down to produce sugars, which then the yeasts consume to make all of the beautiful bourbon.
IRA FLATOW: Anybody make a bourbon out of quinoa?
MARIANNE BARNES: Oh, I’ve heard of it.
IRA FLATOW: Give her an idea, I get 10%. OK, our official scorekeeper, Annie. What’s the score?
ANNIE NERO: Well, team Hot Toddy has one point, and team Old-Fashioned also has one point.
IRA FLATOW: Oh, it’s pretty close, OK. Ready for our next question. This question– thank you– this question, number two, is worth two points now, because they are getting harder. We’re going to talk about distillation. The distillation process separates ethanol, which is the good stuff that we want, from water by heating the liquid mixture.
And this happens because A, water is less dense than ethanol, B, water has a lower boiling point than ethanol, C, ethanol has a lower boiling point than water, or D, water and ethanol have similar boiling points. You have 15 seconds starting now. Why does that happen? Think amongst yourselves out there. Well, that seems like it took forever. Time’s up. This time we’re going to start with Old-Fashioned team. What do you choose?
TEAM OLD-FASHIONED: We’re going to go with C.
IRA FLATOW: C. You think ethanol has a lower boiling point than water. And let’s go over to Hot Toddies. What was your choice?
TEAM HOT TODDY: We’re going to go with A.
IRA FLATOW: What does the audience think?
AUDIENCE: C.
IRA FLATOW: C. And the answer is?
MARIANNE BARNES: C is the correct answer.
IRA FLATOW: C is the correct answer. Tell us why that’s important.
MARIANNE BARNES: So when you think about distillation and the process of distillation, it all has to do with the difference in those two temperatures. So the bottom of the still, whether it’s a pot still or a column still, that’s where you get your hottest temperature, at the heat source.
So your alcohol and your water are both going to turn into a vapor, but as it moves up in the still, it’s going to lose temperature. It’s going to lose energy. The alcohol will stay in a vapor phase and the water will turn back into a liquid and head out of the still. So you’re condensing your alcohol back into a liquid and that’s when it goes into the barrel.
IRA FLATOW: So it sounds like you’re starting out actually making beer and then converting it?
MARIANNE BARNES: Absolutely.
IRA FLATOW: Is that’s what’s happened?
MARIANNE BARNES: Yes. So through the mashing process and fermentation, you turn it from, we call it mash, into distillers beer, and then you strip off your alcohol during the distillation process.
IRA FLATOW: Now I know with Castle and Key, you’re also making gin and vodka. What’s the difference between that? Why do you do that?
MARIANNE BARNES: So if you think about the vodka and the way that it’s distilled, we take it up to 190 proof plus. And at this point, you’ve taken all of the flavor out, so it’s very pure. We have regulations in bourbon that it has to be distilled below 160, and that’s to preserve a lot of the flavor. So that’s the biggest difference.
IRA FLATOW: Wow. Now we’re going to move on. Annie, what’s our score? Where are we now?
ANNIE NERO: Team Hot Toddy has one point, while team Old-Fashioned has three points.
IRA FLATOW: Team Old-Fashioned is pulling ahead. We’re going into the far turn. All right, question number three, worth– thank you– worth three points now. Ethanol breaks down the charred barrel over time. What part of the wood contributes to the vanilla flavoring? Is it A, lignin, B, oak lactones, C, tannins, or D, McCormick’s vanilla extract? Time’s starting now. Somebody was having fun with the questions here. Which one? All right, let’s go over to team Hot Toddy. What do you say?
AUDIENCE: We’re going to go with C, tannins.
IRA FLATOW: C, tannins. Old-Fashioneds, what do you think?
AUDIENCE: B.
IRA FLATOW: Audience, what do you say?
AUDIENCE: [INTERPOSING VOICES]
IRA FLATOW: Everybody’s all over the place. What’s the right answer?
MARIANNE BARNES: The correct answer is A.
IRA FLATOW: Oh, tell us why. Wow, everybody got that wrong.
MARIANNE BARNES: Yeah.
IRA FLATOW: We love that.
MARIANNE BARNES: Yeah. I’m going to give you some real science here. So the wood lignin, if you think about it, it’s like a ligament. So this is what holds the cellulose and the hemicellulos of the barrel together. So it’s in the presence of heat and alcohol that you start to break down those lignins into different acids. Coniferyl acid is the one that turns into coniferyl aldehyde in the presence of oxygen, and then that turns into vanillin, which is the vanilla flavor.
IRA FLATOW: Ah. What kind of wood is the barrel made out of?
MARIANNE BARNES: So the barrel must be oak, and for bourbon, it has to be new charred oak. A lot of people think that it has to be white oak, but there’s actually not a regulation there.
IRA FLATOW: Oh, is that right?
MARIANNE BARNES: That’s right.
IRA FLATOW: Wow, wow. Can you age? Can you age the wood? What, do you just literally charcoal it, the flame?
MARIANNE BARNES: The barrel making process is really interesting to me. We call them coopers, the people that make the barrel. They are artisans. The process that most people use– the tree, to start with, has to be at least 40 years old.
IRA FLATOW: No kidding.
MARIANNE BARNES: That’s right. You get basically one barrel per tree, and you have to cut it in a very particular way so that the grains lock together when you assemble a barrel so that it doesn’t leak. You often do what we call seasoning the wood. You leave it in the environment and it starts to break down some of these components, such as the tannins, and softens the wood and makes it a little more palatable.
IRA FLATOW: Wow.
MARIANNE BARNES: So seasoning.
IRA FLATOW: I didn’t realize all that stuff going into it. Wow.
MARIANNE BARNES: Yeah.
IRA FLATOW: Let’s ask Annie, our scorekeeper, what’s our score at this point?
ANNIE NERO: Team Hot Toddy with one, Team Old-Fashioned with three points.
IRA FLATOW: I’m Ira Flatow, and this is Science Friday from Public Radio International. You’re listening to our bourbon quiz, recorded at the Brown Theater in Louisville, Kentucky. Let’s go back to the stage for our final question.
OK, we’re going into the last question here. There’s a lot of science going on into making a bourbon, like we were just talking about it. What kind of science can you do with the bourbon? Hm. Question 4 is worth four points. Chance to make it up here.
Which of these– this is a little more difficult, you have to watch this– which of these is not a real study? Which is a fake news about bourbon or whiskey? Choose the fake study. Is it A, what are the effects of ethanol and bourbon on maze learning and goldfish? B, can heated whiskey and other alcoholic beverages induce superconductivity in iron-based compounds? Is it C, can whiskey and ethanol be used to prevent wound infection in emergency settings? D, how does the microgravity of space affect the maturation process of bourbon?
Remember, which of these is not a true study? The effects of bourbon maze on goldfish. Can whiskey induce superconductivity in iron? Can whiskey be used to prevent wound infection? How does the microgravity of space affect bourbon maturation? Which is a phony study? The other three are real. Time’s up. Let’s see what the teams came up with. Team Hot Toddy, tell us what you guess. You don’t agree with each other. Take a vote.
TEAM HOT TODDY: The goldfish is so ridiculous, but it’s like so ridiculous that it’s true, so let’s go with D.
IRA FLATOW: He just changed it?
TEAM HOT TODDY: Yeah.
IRA FLATOW: See, I thought you went to D. OK, D. What do you guys say?
TEAM OLD-FASHIONED: I’m going to go with B.
IRA FLATOW: B. Audience, what do you think?
AUDIENCE: [MIXED LETTERS]
IRA FLATOW: [MUMBLING A LETTER]
The correct answer is C. That is not a real study. You see it in the movies, right? They’re always putting [MUMBLE] on the wounds. Nah. It’s not real. No one has ever studied to see if that one is real. You do experiments with bourbon, you’ve never tried this one, right?
MARIANNE BARNES: So this is the one that I feel like is the most likely, which is hilarious, right? Because you see people with their bottle of whiskey in old westerns.
IRA FLATOW: Yeah. Chew on this leather strap and we’ll pour the whiskey on it in the meantime. Annie, what’s our final score?
ANNIE NERO: Well, the final score is team Hot Toddy with one point, and team Old-Fashioned with three points.
IRA FLATOW: Team Old-Fashioned, wow. Thank you all. Thanks for playing the show. Thank you, contestants.
That was a bourbon quiz with master distiller Marianne Barnes, recorded at the Brown theater in Louisville, Kentucky. That’s all the time we have for today and for the year. This is our last sci-fi broadcast of 2017. Thank you, and happy new year.
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