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

Ask any coffee aficionado, and they’ll tell you: A good cup is about more than the beans. The flavor is affected by lots of things – the roast and fermentation of the beans, the coarseness of the grind, the brewing temperature and even the chemicals in the water used to brew it. But there are very few quantitative ways to assess all the flavor variations. Current industry standards measure the concentration of coffee, but they often miss qualities like the acidity, brightness and fruitness. Scientists at the University of Oregon are trying to change that https://www.nature.com/articles/s41467-026-71526-5 using a tool called a potentiostat that’s often used to measure the charge in batteries. Interested in more food and beverage science? Email us your question at [email protected] mailto:[email protected] and we may turn it into an episode! 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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• 0:18Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:23Speaker 02

  Hey, Short Wavers. Emily Kwong here.

• 0:25Emily Kwong?

  And Rachel Carlson with our biweekly Science News Roundup.

• 0:28Speaker 02

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

• 0:35Speaker 03

  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.

• 0:41Speaker 02

  We love it. We love it.

• 0:42Emily Kwong?

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

• 0:48Speaker 03

  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?

• 0:55Speaker 02

  I'm so jealous.

• 0:56Emily Kwong?

  A house divided.

• 0:57Speaker 02

  Emily and I both need coffee in the morning to function. Sorry, Emily, for calling you out.

• 1:02Emily Kwong?

  Affirmative.

• 1:02Speaker 02

  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 scorpions' arsenal of weapons at the molecular level.

• 1:15Speaker 03

  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.

• 1:23Emily Kwong?

  Stuff of nightmares.

• 1:24Speaker 02

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

• 1:32Emily Kwong?

  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 Short Wave, the science podcast from NPR.

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• 3:04Emily Kwong?

  Okay, Rachel and Sasha, we have so much to get through today. Sasha, I'm gonna let you pick the first story. Where do you want to start?

• 3:11Speaker 03

  Why don't we start with coffee, since it's where so many people start their days?

• 3:15Emily Kwong?

  Fair.

• 3:15Speaker 02

  Here's the thing about coffee. It's extremely variable. Visit the barista at your local fancy café 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.

• 3:31Emily Kwong?

  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.

• 3:47Speaker 03

  All right, we say problems. What kind of problems related to coffee?

• 3:50Emily Kwong?

  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.

• 4:03Speaker 02

  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.

• 4:12Emily Kwong?

  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.

• 4:28Speaker 05

  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.

• 4:38Emily Kwong?

  This is Christopher Hendon, a chemistry professor and a coffee expert. And he's the lead researcher on a study about this in the journal Nature Communications.

• 4:46Speaker 03

  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.

• 4:53Emily Kwong?

  Totally, totally.

• 4:54Speaker 03

  But tell us how voltage measures what? And is it actually a useful measurement to coffee makers?

• 5:01Emily 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. 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.

• 5:27Speaker 05

  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.

• 5:40Emily Kwong?

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

• 5:41Speaker 02

  I didn't either.

• 5:42Emily Kwong?

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

• 5:45Speaker 03

  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.

• 6:00Emily Kwong?

  Yes, so a recent study in the journal Communication 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.

• 6:14Speaker 03

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

• 6:26Emily Kwong?

  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.

• 6:45Speaker 02

  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.

• 6:54Speaker 03

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

• 6:58Emily Kwong?

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

• 7:21Speaker 02

  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.

• 7:33Speaker 06

  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.

• 7:47Emily Kwong?

  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.

• 7:58Speaker 03

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

• 8:02Speaker 02

  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.

• 8:09Speaker 03

  Oh, really?

• 8:09Speaker 02

  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.

• 8:16Speaker 03

  Good advice. All right, for our third item, something all of us hope will never be in our dreams, and this is scorpions.

• 8:23Speaker 02

  Yes.

• 8:24Speaker 03

  And their anatomical weaponry. Tell us about this.

• 8:26Speaker 02

  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.

• 8:38Speaker 03

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

• 8:42Speaker 02

  Yeah, that's part of the idea. It's a very heavy metal trait, you could say. And researchers wanted to find out why these metals might be in scorpion weapons, and whether a scorpion's hunting style could have anything to do with it.

• 8:55Emily Kwong?

  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.

• 9:05Speaker 03

  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?

• 9:15Emily Kwong?

  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.

• 9:24Speaker 02

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

• 9:38Emily Kwong?

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

• 9:43Speaker 03

  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?

• 9:54Speaker 02

  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's stingers or find ways to build their hard shells.

• 10:13Emily Kwong?

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

• 10:20Speaker 03

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

• 10:25Emily Kwong?

  That's smart.

• 10:29Emily Kwong?

  Well, Sasha, let's end there. This was so much fun. Please, please come back soon.

• 10:33Speaker 02

  Yes, it was a delight.

• 10:34Speaker 03

  Yes, it's always fun to do this with you. Thank you so much.

• 10:37Speaker 02

  And short waivers for more science stories just like these. Follow Short Wave on the NPR app or wherever else you're listening from.

• 10:44Emily Kwong?

  The app is honestly very cute.

• 10:46Speaker 02

  It is.

• 10:46Emily Kwong?

  It's got such great integration of podcasts with broadcasts, with digital stories, and it's just like stuff to help you know what's going on in the world. We all know our phones are full of distractions, but you can make your phone a portal of insight and information and occasionally scorpion science. Download the NPR app now and sign up for push notifications so you can know when the latest Short Wave episode drops. This episode was produced by Jeff Pierre and Hannah Chin. It was edited by Rebecca Ramirez and

• 11:17Speaker 02

  Christopher Intagliata. Tyler Jones checked the facts. Sina Lefredo was the audio engineer. I'm Rachel Carlson. And I'm Emily Kwong. Thank you for listening to Short Wave, the science podcast from NPR.

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