Could labs replace your natural chocolate?

Chocolate may fill grocery store shelves around the world, but the raw product that powers chocolate is far more selective. The majority of chocolate farms are found in West Africa and South America – just 20 degrees north or south of the equator. Each farm produces chocolate of a different flavor. Some cocoa tastes fruitier; others, more floral. Nutty. Earthy. Spicy. But what drives these different flavor profiles? And can it be recreated in a lab? A team led by scientists at the University of Nottingham in the UK sought to find out and published their results in the journal Nature Microbiology https://www.nature.com/articles/s41564-025-02077-6 this week. Curious about other ways science intersects with food? Email us at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:19Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:24Emily Kwong?

  Hey, Shortwavers. Hannah Chen here. And Emily Kwong. With our twice monthly Science News roundup, featuring the hosts of All Things Considered. And today, we have Mary Louise Kelly. We do.

• 0:34Speaker 02

  And I am so here for this because I hear we're talking about my favorite topic, chocolate, and what makes it delicious.

• 0:40Emily Kwong?

  Yes. We're also going to talk about how birds at sea poop way more than scientists thought. Plus, the molecules that might be responsible for your daytime sleepiness.

• 0:51Speaker 02

  Sorry, nodded off there. Go on.

• 0:54Emily Kwong?

  All that on this episode of Short Wave, the science podcast from NPR.

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• 2:23Speaker 02

  All right. To start off, we are talking chocolate. I am here all day and every day for great tasting chocolate. What do we got?

• 2:31Emily Kwong?

  Fantastic. Okay, so published in the journal Nature Microbiology, this research focuses on cocoa beans.

• 2:36Speaker 02

  Cocoa beans, which make chocolate, which grow on trees.

• 2:39Emily Kwong?

  Yeah, they do. And depending on where you go, you kind of get different flavor profiles from those cocoa beans. So it could be fruity, or floral, or spicy. And a team led by scientists at the University of Nottingham wanted to figure out what was driving these different flavor profiles, specifically at the level of microbes.

• 2:56Speaker 02

  The level of microbes, so very, very tiny microorganisms. How are microbes involved in how chocolate tastes?

• 3:03Emily Kwong?

  Well, after farmers pick cocoa beans, they ferment them, kind of let them sit in boxes or bags for days on end.

• 3:09Speaker 04

  They do this because this is what has been taught to them, generation, so from their parents.

• 3:14Emily Kwong?

  Research fellow David Gopulchun said it's during fermentation that these microbial communities emerge, and they give rise to all kinds of flavor compounds for the chocolate.

• 3:23Speaker 02

  Never thought about this. Do we know which microbes produce the best tasting chocolate?

• 3:28Emily Kwong?

  Well, Mary Louise, best is kind of subjective, but the researchers did sample the microbes from three different farms in Colombia. They genetically sequenced the DNA from these microbes, and then they built a computer model to see how those tiny organisms interacted. Then they went full Willy Wonka. Basically, the team created a cocktail of these microbes to start performing fermentation directly on beans in the lab to create their own chocolate flavor compounds. And it worked. Professional tasters confirmed that these beans, fermented with a synthetic microbial community, exhibited flavor notes similar to fine chocolate. Really?

• 4:04Speaker 02

  I'm skeptical. What did they taste like?

• 4:06Emily Kwong?

  David said it was really fruity, kind of bright and berry flavored.

• 4:10Speaker 02

  So I'm thinking through the implications. More chocolate, that I'm pro more chocolate. But if scientists can just recreate, recreate chocolate flavors in a lab, what does that mean for the poor cocoa bean and for small time chocolate farmers?

• 4:24Emily Kwong?

  Yeah, I mean, it could be disruptive. But one thing to know about the state of chocolate right now is that there's a worldwide cocoa shortage due to climate change. Maybe the science could lead to fermentation starters that can make the process more predictable.

• 4:37Speaker 02

  Wow. Okay, on a considerably more disgusting note, let's move on. Story number two, the bathroom habits of seabirds. Why, who wants to study this and why?

• 4:49Emily Kwong?

  It was kind of an accident. So a postdoc from the University of Tokyo, Leo Uesaka, was actually looking at the legs of these seabirds, which are called streaked shearwaters. He was studying how the birds take off from the water. And to do that, he'd strapped cameras to their bellies, facing backwards, towards their behinds. And that's when he noticed something that really caught his interest. Which was that they almost always took off to poop. And they were doing it way more and way more regularly than he thought they would. So Leo started a whole new research project to investigate.

• 5:22Speaker 02

  And what did he find out?

• 5:23Emily Kwong?

  Well, he ended up combing through more than 30 hours of bird bathroom tape, which he describes as Mentally difficult.

• 5:34Speaker 02

  Oh, go science. Such a labor of love.

• 5:37Emily Kwong?

  That's what we chant to ourselves every day in the mirror. And Leo found that while at sea, these birds defecate an average of every four to 10 minutes. And that didn't change based on their eating habits. They were going that often. And after doing some calculations, Leo concluded that birds lost 5% of their body mass every hour.

• 5:56Speaker 02

  Every hour?

• 5:57Emily Kwong?

  From defecating.

• 5:59Speaker 02

  I mean, I guess if you're going every four minutes, I buy that. But I'm trying to figure out, we have all seen birds go to the bathroom. We've all seen that they do this frequently. Is this really groundbreaking?

• 6:13Emily Kwong?

  Well, a lot of estimates for how much seabirds excrete is based on land observations, but Leo's cameras and the research that he published in Current Biology gave both him and us a rare look at the bird's behavior at sea.

• 6:26Speaker 02

  At sea. And why is that important?

• 6:28Emily Kwong?

  Well, one reason is that feces or guano is important for how nutrients cycle in environments. Independent biologist Daniel Plaza studies how ecosystems function, and he says that fishing regulations, catch limits, they can be based on researchers' estimations of how much fish the birds need to eat to survive.

• 6:47Speaker 04

  If we underestimate how much poop they are doing, and it probably is connecting with how much food they are taking, we'd also underestimate how much food they need.

• 6:57Emily Kwong?

  So basically, if birds are eating way more than previously thought, we'd need to reduce fishing further to give the seabirds more opportunities to catch the fish that they need to survive.

• 7:07Speaker 02

  Moving right on. Our last story, we are tackling the causes of daytime sleepiness. I'm going to refresh my coffee and chug some caffeine while we work our way through this one. But daytime sleepiness, excessive daytime sleepiness, is this common?

• 7:22Emily Kwong?

  Apparently, yes. Excessive daytime sleepiness, EDS, happens when people fall asleep repeatedly during the day. This condition affects up to 1 in 3 people in the US. It's very common. And while it's often linked to sleep deprivation or other circadian disorders, EDS can still happen to people who are getting a full night's sleep. Plus, it's correlated with a higher risk of things like cardiovascular disease or hypertension.

• 7:46Speaker 02

  1 in 3 people, you said. Hannah, how do we find out if we're among them?

• 7:51Emily Kwong?

  Well, there's this survey called the Epworth Sleepiness Scale that's designed to measure daytime sleepiness. It basically gives you a list of activities, anything from reading a book, to watching TV, to riding in a car, and then it asks, how likely are you to doze off during each of these activities?

• 8:05Speaker 02

  And I'm going to guess that if you have a high likelihood of dozing off during multiple things, like watching TV, riding in a car, you're going to score higher on the sleepiness scale?

• 8:13Emily Kwong?

  Yes. Researchers gave this survey to 6,000 volunteers, and then they collected their blood samples to see if there were any molecules in the volunteers' blood that were associated with higher or lower self-reported daytime sleepiness. I just talked to Tarek Fakhi. He was the lead author of this study, which just published Tuesday in the journal eBiomedicine. And that study focused in on metabolites, these little molecules that can come from things like diet or medication.

• 8:39Speaker 05

  The most popular one I think people know is cholesterol. It's one of many, like thousands of metabolites in our bodies. There's so many of them.

• 8:47Emily Kwong?

  Altogether, Tarek and his team looked at 877 different metabolites, and then they found 10 that seemed to be linked, either positively or negatively, to people's self-reported sleepiness. Notably, a metabolite of tyramine, which is found in fermented foods, aged cheese, and alcohol, was associated with higher rates of self-reported daytime sleepiness, particularly in men. And on the other hand, they found that omega-3 and omega-6 fatty acids, which you find in foods like fish or vegetable oils or nuts and seeds, were associated with lower rates of reported sleepiness.

• 9:17Speaker 02

  So what does this mean for me? Let's bring it back to what we should be eating. It sounds like more fish, less old cheese and alcohol if we want to stay awake.

• 9:28Emily Kwong?

  Your charcuterie board is doomed. So it's really too early to tell. Tarek wants to do a clinical trial next, giving people different types of diets, maybe richer in certain metabolites and not others, to kind of see how they affect people's daytime sleepiness. So we'll come back to you and let you know when the food to sleepiness science is a little more clear.

• 9:46Speaker 02

  I will look forward to it.

• 9:47Emily Kwong?

  Exactly. In the meantime, Mary Louise, thank you so much for coming on the show. It's great to have you here.

• 9:52Speaker 02

  Totally. My pleasure. Thanks so much for having me.

• 9:55Emily Kwong?

  We appreciate you. And you can hear more of Mary Louise Kelly on Consider This. That's NPR's afternoon podcast about what the news means for you. This episode was produced by Burley McCoy, Rachel Carlson, and Jordan Murray-Smith. It was edited by Rebecca Ramirez and Christopher Intagliata. Tyler Jones checked the facts. Tiffany Vera Castro was the audio engineer. I'm Emily Kwong. And I'm Hannah Chin. Thanks for listening to Short Wave, the science podcast from NPR.

• 10:27Speaker 03

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