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Short Wave

Coffee is complex. Can science standardize it for the better?

01 May 2026

Transcription

Chapter 1: What factors affect the flavor of coffee?

1.718 - 22.024 Unknown

On Consider This, NPR's afternoon news podcast, we cover everything from politics to the economy to the world. But every story starts with a question. At NPR, we stand for your right to be curious, to make sense of the biggest story of the day and what it means for you. Follow Consider This wherever you get your podcasts.

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24.787 - 28.452 Rachel Carlson

You're listening to Shortwave from NPR.

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29.866 - 35.015 Emily Kwong

Hey, short wavers. Emily Kwong here. And Rachel Carlson with our biweekly science news roundup.

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35.196 - 41.648 Rachel Carlson

And this time with a special guest, our colleague Sasha Pfeiffer. Sasha, how's your love of science these days?

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41.888 - 47.578 Sasha Pfeiffer

Well, I, as I think you two know, I am married to a science teacher. So I would say that my love of science is always pretty high.

47.699 - 48.921 Rachel Carlson

We love it. We love it.

Chapter 2: What problems arise from current coffee measurement standards?

48.981 - 53.95 Rachel Carlson

Shout out to all science teachers. Question for you. Is your husband or are you a coffee drinker?

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54.571 - 61.64 Sasha Pfeiffer

He is. I am not. I try not to be dependent on it. And I also honestly need so much sugar in it that I just figure why make that a habit.

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62.12 - 69.51 Emily Kwong

I'm so jealous. A house divided. Emily and I both need coffee in the morning to function. Sorry, Emily, for calling you out. Affirmative.

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Chapter 3: How can electrochemistry improve coffee flavor assessment?

69.53 - 81.945 Emily Kwong

Sasha, we are more than coffee aficionados on the show. We also have updates for you on dream research and what's going on in Scorpion's arsenal of weapons at the molecular level.

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82.162 - 90.169 Sasha Pfeiffer

I think I read a little bit about this. This is kind of the makeup of their stingers and their claws and all that other terrifying weaponry that is built into their bodies.

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90.229 - 97.675 Emily Kwong

Stuff of nightmares. Exactly. And you can let us know at the end if it's more exciting and cool to know about scorpions or terrifying.

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99.317 - 121.984 Rachel Carlson

So today on the show, from your dreaming hours and waking coffee-making hours indoors to your time with critters outdoors, science has fun answers for you. You're listening to Shortwave, the science podcast from NPR. Okay, Rachel and Sasha, we have so much to get through today.

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Chapter 4: What insights does research provide on coffee roasting?

122.065 - 124.833 Rachel Carlson

Sasha, I'm going to let you pick the first story.

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124.853 - 129.688 Sasha Pfeiffer

Where do you want to start? Why don't we start with coffee since it's where so many people start their days?

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130.008 - 146.474 Emily Kwong

Fair. Here's the thing about coffee. It's extremely variable. Visit the barista at your local fancy cafe, and they'll tell you the flavor of your cup is affected by so many different things, like the coffee beans, the way those beans were fermented and roasted, the temperature it's brewed at, the chemicals in the water that you use to brew it.

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146.615 - 161.848 Rachel Carlson

Oh, you're making me want coffee. And even though there's a technique the industry uses to measure the concentration of coffee, that misses those other aspects of flavor, like acidity or brightness or fruity or sweetie or nutty notes that coffee drinkers care about, which causes all kinds of problems.

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162.014 - 165.182 Sasha Pfeiffer

All right, when we say problems, what kind of problems related to coffee?

165.643 - 178.453 Rachel Carlson

Yeah, with, say, the degree of bean roasting. You know, coffee consumers may be familiar with roast type, a light, medium, or dark roast. But a light roast from a national coffee chain may be considered a dark roast by your local gourmet coffee house.

178.585 - 187.415 Emily Kwong

So scientists at the University of Oregon wanted to see if they could change that. They used a tool that's usually used to measure the charge in batteries to assess the flavor of coffee.

187.715 - 202.872 Rachel Carlson

Sasha, they basically ran voltage through a cup of coffee. And based on the electrochemical response, the scientists found they could get a quantitative sense of the acid levels and the intensity of a cup of joe. Basically, they could tell how strong the coffee was and how dark the roast was.

202.919 - 212.902 Christopher Hendon

You're just basically sticking two pieces of conductive metal into coffee, and then the coffee acts as a resistor, and at different voltages, you have different molecules reacting with that applied voltage.

Chapter 5: How do personality traits influence dream content?

220.908 - 235.886 Sasha Pfeiffer

You know, because you said they use a tool that's usually used to measure the charge in batteries, I feel like there's definitely a coffee battery acid joke here. Totally. Tell us how voltage measures what and is it actually a useful measurement to coffee makers?

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235.906 - 246.559 Emily Kwong

It is. Yeah. Based on the test they ran, this method was at least as good as human experts at telling when a roast is bad. And Christopher is an expert. He used to coach in the competitive coffee circuit.

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247.081 - 261.404 Emily Kwong

But Sasha, just to be clear, this doesn't mean that coffee tasting is going to be outsourced to lab devices. But Christopher is hoping it could help the industry develop a more numbers-based way to describe those tastes, sort of like the International Bitterness Units in beer.

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261.825 - 274.405 Christopher Hendon

In the beer industry, they have IBU, which is somehow inferring how hoppy a beer is going to be, and they put a number on it. And so there's nothing that prevents us from implementing something very similar based on this measurement on coffee bags.

274.688 - 276.492 Rachel Carlson

I didn't know IBU existed, by the way.

Chapter 6: What methods do researchers use to study dreams?

276.552 - 280.139 Rachel Carlson

I didn't either. I had no idea. Because I don't love hops, you know?

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280.2 - 294.79 Sasha Pfeiffer

And I didn't know there was a competitive coffee circuit. So all of us have some Googling to do later. All right. So we started with coffee, which is how many people start their days. Now let's go with how many people end their days, dreams. Tell us about the dream research you're looking into.

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295.04 - 309.218 Rachel Carlson

Yes. So a recent study in the journal Communications Psychology has some new insights for all of us dreamers on how personality and behavior traits may predict the types of dreams we have. Because some people's dreams are more vivid and others are more fragmented.

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309.417 - 320.519 Sasha Pfeiffer

Yeah, and I definitely fall in the category of people who can wake up and have just had a very intense dream, but then you forget it so quickly. So given that dreams fade quickly, how do scientists study them?

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321.16 - 339.374 Rachel Carlson

Yeah, so for two weeks, over 200 participants recorded voice memos of everything that was going through their mind just before they woke up. They also recorded their thoughts during the day, and they filled out questionnaires to assess different aspects of their personality. They also wore devices to track their sleep and waking patterns in bed.

339.855 - 349.011 Emily Kwong

Researchers at the IMT School for Advanced Studies, LUCA, in Italy then analyzed all of this data to see if any patterns emerged between who people were and the contents of their dreams.

349.332 - 352.317 Sasha Pfeiffer

Yeah, and tell us, what patterns? How does personality affect dreaming?

352.702 - 366.421 Rachel Carlson

Yeah, there were some stable patterns. So participants more prone to mind wandering tended to report more bizarre dreams, particularly dreams that rapidly change scenarios. So like you're in a hospital, you're on a desert, you're on a beach, what's happening?

Chapter 7: What discoveries have been made about scorpion anatomy?

367.363 - 375.514 Rachel Carlson

Whereas people who assigned more value and meaning to their dreams tended to have richer ones, more vivid and perceptual dreams.

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375.895 - 387.772 Emily Kwong

Lead author Valentina Elcha also found people who self-reported having better sleep quality also had more immersive dreams. And this aligns with an idea in psychology that dreams are guardians of good sleep.

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388.413 - 402.476 Valentina Elcha

Maybe the fact that we experience this very vivid dream is a way of the brain to protect our sleep, to let us into immersive worlds. where we can be less affected by the external environment.

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402.496 - 413.073 Rachel Carlson

Valentina also is the first to acknowledge that because the study depends on the reports of the participants, it has its limitations. They're not studying dreams, right? They're studying reports about dreams.

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413.174 - 417.1 Sasha Pfeiffer

Did she have any advice beyond just write it down quickly how you can remember your dreams better?

417.08 - 431.137 Emily Kwong

She did. Record your thoughts, she says, the moment you wake up in the morning. I actually do this almost every morning when I remember. And Valentina said a voice recording could actually be better than writing it down to get all those juicy details in before the dream floats away.

432.058 - 441.349 Sasha Pfeiffer

Good advice. All right. For our third item, something all of us hope will never be in our dreams. And this is scorpions and their anatomical weaponry. Tell us about this.

441.38 - 452.854 Emily Kwong

So scorpions have two weapons of choice. They're stingers to inject their prey with venom or death by claw. And it turns out these weapons are fortified with metal like zinc, manganese, and iron.

453.154 - 457.459 Sasha Pfeiffer

Oh, that is so interesting. Metal that I guess gives them strength. Is that the idea?

Chapter 8: How can scorpion research inform material science?

470.236 - 479.611 Rachel Carlson

Yeah, because some scorpions mostly hunt with their stingers, whereas others rely more on their claws. For example, the Trinidad thick-tailed scorpion tends to favor its stinger.

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480.211 - 489.406 Sasha Pfeiffer

So is the idea that scientists are trying to figure out if whatever weaponry the scorpion uses, there's more metal in that part of their body?

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489.927 - 498.64 Rachel Carlson

Exactly, yes. That was the question. So scientists use microscopy and micro X-ray imaging to look at 18 species across the scorpion tree of life.

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498.839 - 512.469 Emily Kwong

They found that iron, for example, was only found in scorpion claws, and manganese was only found in scorpion stingers. The researchers think that's because manganese could help harden stingers while maybe iron protects their claws from wear over time.

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513.211 - 518.282 Rachel Carlson

And all of that could support the idea that different metals may be related to different hunting methods.

518.583 - 528.821 Sasha Pfeiffer

That is so fascinating. But I am going to ask you the applied science question. So where do researchers want to go with this and how do they think that could inform human understanding of the world?

529.442 - 547.9 Emily Kwong

Right. Well, it turns out there are thousands of scorpion species. So future research could and probably should look at even more scorpions to see how these patterns play out. And the researchers said that one day it could be applied to things like material science, like trying to mimic scorpion stingers or find ways to build their hard shells.

548.401 - 554.733 Rachel Carlson

So with all that being said, Sasha Pfeiffer, do you find scorpions more exciting and cool or more terrifying?

555.134 - 559.963 Sasha Pfeiffer

I'm going to say equal parts of both. A good mixture of fear and respect.

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