Could labs replace your natural chocolate?

Summary

Short Wave – Episode Summary

Episode: "Could labs replace your natural chocolate?"

Date: August 22, 2025
Hosts: Emily Kwong, Hannah Chin
Guest: Mary Louise Kelly (from All Things Considered)
Length: ~10 minutes (core content)

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Overview

This fast-paced episode of Short Wave dives into three intriguing science stories:

1. How microbes shape the complex flavors of chocolate and whether lab techniques could one day "replace" traditional chocolate fermentation.
2. The surprisingly frequent bathroom habits of seabirds at sea and the ecological importance of their excretions.
3. New research into blood metabolites and what they reveal about why some people are sleepier during the day—even with enough rest.

Throughout the episode, the hosts bring lively banter, curiosity, and humor, making complex science fun and accessible.

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Key Discussion Points & Insights

1. Could Labs Replace Your Natural Chocolate?

[02:12–04:13]

• The Science Behind Chocolate Flavor

  • Research published in Nature Microbiology focuses on how microscopic communities (microbes) on cocoa beans influence chocolate’s taste.
  • Chocolate flavors vary according to where cocoa is grown—flavors can be "fruity or floral or spicy" (Hannah Chin, [02:28]).
  • Scientists from the University of Nottingham wanted to understand which microbes contribute to these flavor profiles.

• Microbial Fermentation

  • Fermantation is a crucial step after beans are harvested—microbes create flavor compounds.
  • "It's during fermentation that these microbial communities emerge and they give rise to all kinds of flavor compounds for the chocolate." (Emily Kwong, [03:03])

• Synthetic Fermentation in the Lab

  • Scientists sequenced DNA from microbial samples on Colombian farms, modeled their interactions, and then created a "cocktail" of these microbes to ferment cocoa beans directly in the lab.
  • Lab fermentation successfully produced distinct chocolate flavors, confirmed by professional tasters as similar to high-quality chocolate.

• Implications for the Cocoa Industry

  • Potential to make chocolate production more predictable amid worldwide cocoa shortages due to climate change.
  • Raises ethical and economic questions for small farmers if lab-based techniques become widespread.
  • "If scientists can just create, recreate chocolate flavors in a lab, what does that mean for the poor cocoa bean and for small time chocolate farmers?" (Mary Louise Kelly, [03:59])

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2. Seabirds' Astonishing Bathroom Habits at Sea

[04:13–06:47]

• Accidental Discovery

  • University of Tokyo postdoc Leo Uesaka, studying seabird movement, noticed unexpected data from cameras strapped to streaked shearwaters' bellies.

• An Unexpected Pattern

  • Seabirds were "almost always took off to poop" ([05:00], Hannah Chin).
  • Analysis of 30+ hours of footage showed seabirds defecate every 4–10 minutes while at sea, regardless of eating habits.
  • This results in birds losing 5% of their body mass every hour from defecation. (Leo Uesaka, via Emily Kwong, [05:25])

• Scientific Significance

  • Previous estimates of seabird poop were based on land observations; this is a rare glimpse into behavior at sea.
  • Guano is vital for nutrient cycling in the ecosystem. The study affects how researchers estimate seabird food needs—a critical input for fishing regulations and conservation.

• Ecological Implications

  • "If we are underestimate how much poop they are doing and it probably is connecting with how much food they are taking, we also underestimate how much food they need." (Daniel Plaza, [06:36])

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3. What Makes Us Sleepy During the Day?

[06:57–09:31]

• Prevalence of Excessive Daytime Sleepiness (EDS)

  • "This condition affects up to one in three people in the U.S. it's very common." (Emily Kwong, [07:11])
  • EDS can occur even when people get enough sleep at night; it is associated with higher risks of cardiovascular conditions.

• Measuring Sleepiness

  • The Epworth Sleepiness Scale is a survey that assesses how likely a person is to doze off during various daily activities.

• The Role of Blood Metabolites

  • Researchers surveyed 6,000 individuals, then analyzed their blood for 877 molecules (metabolites) potentially linked to sleepiness.
  • Ten metabolites were found to have significant associations—some increasing, some decreasing the likelihood of feeling sleepy.

• Key Findings

  • "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." (Emily Kwong, [08:46])
  • Omega 3 and 6 fatty acids (in fish, vegetable oils, nuts, and seeds) correlated with less sleepiness.

• Implications for Diet

  • Too early for dietary recommendations; future clinical trials are planned.
  • "Your charcuterie board is doomed." (Emily Kwong poking fun, [09:17])

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Notable Quotes & Memorable Moments

• Microbial Mystery:
  "The level of microbes. So very, very tiny microorganisms. How are microbes involved and how chocolate tastes, well?"
  —Mary Louise Kelly ([02:45])

• Willy Wonka Science:
  "Then they went full Willy Wonka."
  —Hannah Chin ([03:31])

• Lab Chocolate Taste:
  "The beans fermented with a synthetic microbial community exhibited flavor notes similar to fine chocolate."
  —Emily Kwong ([03:42])

• Seabirds Science Humor:
  "Such a labor of love."
  —Mary Louise Kelly, about analyzing seabird footage ([05:23])

• Poop and Conservation:
  "If we are underestimate how much poop they are doing and it probably is connecting with how much food they are taking, we also underestimate how much food they need."
  —Daniel Plaza ([06:36])

• Sleepiness and Cheese:
  "Your charcuterie board is doomed."
  —Emily Kwong ([09:17])

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Timestamps for Key Segments

| Time | Segment Description | |--------|-----------------------------------------------| | 02:12 | Introduction to chocolate flavor research | | 03:03 | Importance of microbial fermentation | | 03:31 | Lab-created chocolate flavors | | 03:59 | Social/economic implications of lab chocolate | | 04:13 | Seabird bathroom behavior discovery | | 05:25 | Seabird excretion frequency and mass loss | | 06:36 | Ecosystem links: poop, fish, and conservation | | 06:57 | Introduction to sleepiness research | | 07:40 | Survey method for sleepiness (Epworth scale) | | 08:46 | Metabolite findings: tyramine and sleepiness | | 09:07 | Omega-3s, omega-6s, and less sleepiness |

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Summary

This episode of Short Wave delivers bite-sized but impactful science. From the future possibilities of lab-fermented chocolate (and concerns for farmers), through the surprising ecological implications of seabird bathroom habits, to the molecules in our blood that may be making us sleepy, the show brings rigorous research and irrepressible curiosity. Playful banter ("Your charcuterie board is doomed") and enthusiastic questioning ("How are microbes involved and how chocolate tastes, well?") make this episode a lively listen for any science lover.

Transcript

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[Emily Kwong]

You're listening to Short Wave from npr.

[Hannah Chin]

Hey, shortwavers. Hannah Chin 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.

[Emily Kwong]

We do.

[Mary Louise Kelly]

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

[Emily Kwong]

Yes. We're also going to talk about how birds at sea poop way more than scientists thought.

[Hannah Chin]

Plus the molecules that might be responsible for your daytime sleepiness.

[Mary Louise Kelly]

Sorry, nodded off there. Go on.

[Hannah Chin]

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

[Mary Louise Kelly]

This.

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[Mary Louise Kelly]

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?

[Emily Kwong]

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

[Mary Louise Kelly]

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

[Hannah Chin]

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.

[Mary Louise Kelly]

The level of microbes. So very, very tiny microorganisms. How are microbes involved and how Chocolate tastes well.

[Hannah Chin]

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

[Fernando Madera]

They do this because this is what has been taught to them generations from their parents.

[Emily Kwong]

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

[Mary Louise Kelly]

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

[Hannah Chin]

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.

[Emily Kwong]

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?

[Mary Louise Kelly]

I'm skeptical. What did they taste like?

[Hannah Chin]

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

[Mary Louise Kelly]

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

[Emily 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 this science could lead to fermentation starters that can make the process more predictable.

[Mary Louise Kelly]

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?

[Emily 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.

[Hannah Chin]

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.

[Mary Louise Kelly]

And what did he find out?

[Hannah Chin]

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

[Mary Louise Kelly]

Ghost science. Such a labor of love.

[Emily Kwong]

That's what we chant to ourselves every 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. Every hour from defecating.

[Mary Louise Kelly]

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

[Hannah Chin]

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.

[Mary Louise Kelly]

At sea. And why is that important?

[Emily 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.

[Fernando Madera]

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

[Hannah Chin]

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.

[Mary Louise Kelly]

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?

[Emily Kwong]

Apparently yes. Excessive daytime sleepiness, EDS happens when people fall asleep repeatedly during the day. This condition affects up to one in three people in the U.S. 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.

[Mary Louise Kelly]

One in three people you said, Hannah. How do we find out if we're among them?

[Hannah Chin]

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 of these activities.

[Mary Louise Kelly]

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.

[Emily 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 volunteer's blood that were associated with higher or lower self reported daytime sleepiness.

[Hannah Chin]

I just talked to Targ Faki. He was lead author of this study which just published Tuesday in the journal Ebiomedicine. And that study focused in on metabolites, these little that can come from things like diet or medication.

[Emily Kwong]

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.

[Hannah Chin]

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.

[Emily Kwong]

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.

[Hannah Chin]

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.

[Mary Louise Kelly]

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

[Emily Kwong]

Your charcuterie board is doomed.

[Hannah Chin]

So it's really too early to tell. Tariq wants to do a clinical trial next, giving people different types of diets, maybe richer in certain metabolites and not others to kind of how they affect people's daytime sleepiness.

[Emily Kwong]

So we'll come back to you and let you know when the food to sleepiness science is a little more clear.

[Mary Louise Kelly]

I will look forward to it.

[Hannah Chin]

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

[Mary Louise Kelly]

Totally my pleasure. Thanks so much for having me.

[Emily 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.

[Hannah Chin]

This episode was Produced by Burleigh McCoy, Rachel Carlson and Jordan Marie Smith. It was edited by Rebecca Ramirez and Christopher Intagliota.

[Emily Kwong]

Tyler Jones checked the facts. Tiffany Vera Castro was the audio engineer. I'm Emily Kwong.

[Hannah Chin]

And I'm Hannah Chin. Thanks for listening to Shortwave, the Science podcast from NPR.

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