Science Friday - Police Behavior Research, Dermatology In Skin Of Color, Coffee Extraction. June 5, 2020, Part 1

Episode Date: June 5, 2020

This week, the killings of George Floyd, Breonna Taylor, and other Black Americans by police brutality and racial inequality continue to fuel demonstrations around the nation. In many cities, police are using tear gas, rubber bullets, and other control tactics on protesters.  A history of 50 years of research reveals what makes a protest safe for participants and police alike. The findings show that police response is what makes the biggest difference: de-escalating and building trust supports peaceful demonstrations rather than responding with weapons and riot gear. And, as thousands of protesters risk abrasive, cough-inducing tear gas and mass arrests, health researchers are concerned a militant response could increase demonstrators’ risk of acquiring COVID-19.  Maggie Koerth, senior science writer for FiveThirtyEight and a Minneapolis, Minnesota resident, joins Ira to discuss these stories.   Dermatologists presented with a new patient have a number of symptoms to look at in order to diagnose. Does the patient have a rash, bumps, or scaling skin? Is there redness, inflammation, or ulceration? For rare conditions a doctor may have never seen in person before, it’s likely that they were trained on photos of the conditions—or can turn to colleagues who may themselves have photos. But in people with darker, melanin-rich skin, the same skin conditions can look drastically different, or be harder to spot at all—and historically, there have been fewer photos of these conditions on darker-skinned patients. And for these patients, detection and diagnosis can be life-saving: people of color get less melanoma, for example, but are also less likely to survive it. Dr. Jenna Lester, who started one of the few clinics in the country to focus on such patients, explains the need for more dermatologists trained to diagnose and treat people with darker skin tones—and why the difference can be both life-saving and life-altering. A cup of coffee first thing in the morning is a ritual—from grinding the beans to boiling the water and brewing your cup. But following those steps won’t always get you a consistent pour. Researchers developed a mathematical model to determine how the size of grind affects water flow and the amount of coffee that gets into the final liquid. Their results were published in the journal Matter. Computational chemist Christopher Hendon, who was an author on that study, talks about how understanding atomic vibration, particle size distribution, and water chemistry can help you brew the perfect cup of coffee. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. A bit later in the hour, why having more black dermatologists could improve skin cancer detection for patients with darker skin, and we'll pour over the science behind your perfect cup of coffee. But first, Americans are protesting in every state in the nation, in scores of cities, people are marching in the streets in opposition to police brutality and racial inequality. In cases where the police respond with barriers, projectiles, tear gas and pepper spray, and mass arrests in a time of pandemic, you can bet there is science, research, saying what actually promotes safety for protesters and police alike. Here to explain is Maggie Kerth, senior science writer for 538.

She joins me from Minneapolis. Welcome back, Maggie. Hi, thank you for having me. You know, this is for me. I know you're out in Minneapolis where all these protests originated following the death of George Floyd. and for me, this is like a deja vu talking with a journalist covering protests because I started my career 50 years ago covering protests. So I can only imagine how difficult it is for you as a journalist

and as a resident of Minneapolis. Tell us a little bit about that. Well, I have been out a couple of times doing reporting in the street. Last Thursday, I had another reporter, a freelancer with The Washington Post, went, ended up at the third precinct when it was being burned. down. And then Saturday night, we were out again when there were very, very few protesters, but a lot of police aggression. So we have kind of seen what the violent end of things looks like from both the protester part and the police part. It's been a really, it's been a really

long week in Minneapolis. The story that I'm talking to you guys about today, I actually filed a little late because I had to help my neighbors hunt through our bushes for incendiary devices. No. Yeah. Yeah. There were a couple of cases where people had found jars full of gas and another case where somebody found a basket that was full of gasoline-soaked firewood. And so everybody in town all of a sudden found out about this and had to kind of go out and look for it. Wow.

Sorry to hear that. I know there have been a lot of stories about the conduct of the protesters and the conduct of the police in response to them, questions about looting and vandalism by some protesters and questions of police escalating the conflict into violence, even when protesters are just sitting there like we saw outside the White House the other day. And I know you reported just this week on what the research says. There is research about what keeps protests safer for everyone involved. and it turns out it's all in the power of the police. Tell us about that. Well, so I thought it was interesting that you were talking about protest 50 years ago because this research on police and

protestor interactions dates all the way back to the 1967 Kerner Commission to investigate urban riots. So the broad consensus is that police escalation of force plays a major factor in whether a peaceful protest turns violent. For example, that Kerner report, which looked at 24 riots in detail, found that police action had been pivotal in starting half of them. And what we're talking about police action, police force here, what we're talking about is pretty broad. The researchers I spoke to described, when peaceful protesters show up at a location and the police are already in riot gear, that can be an escalation of force. And that's actually something that we saw happen in Minneapolis on Tuesday night when the first March in protest of George Floyd's death made it to. the third precinct. There's also things like moving into protesters space and the use of these

less lethal projectiles that we're seeing all over the nation. You know, all of those things are forms of escalating force that can actually increase tension and promote violence happening. Did the study talk about how to de-escalate? That's something that researchers have been working on as well, a lot of this research is qualitative. It's not quantitative because it's really hard to compare one protest, one riot, one uprising to another. The circumstances are all just so different. But the de-escalation side of things, one thing that they all agreed on was that it starts long before there's actually ever a protest looming. It starts with making connections between community and police and not having relationships that allow you to avoid.

the need for a protest to begin with. And other examples that exist out there are things like the Berlin Police Department that has been working really hard at de-escalation techniques. And one of the things that they do is maintaining this constant, transparent communication with protests. So they kind of have information sent out over loudspeakers throughout the entire course of the protests, telling the protesters what they are doing, telling them, you know, where the police are going to be moving next, how things are happening.

and also, you know, kind of sending instructions to the crowd. And everybody kind of talks in this calm, neutral tone of voice that make that, make those voices sound more comforting and more like something people want to listen to. How exactly do you conduct research on protests? I mean, where does the data come from? So this is actually one of the really interesting things to me is that one of the ways these researchers do this work is to go out into the crowds themselves. I talked with Edward McGuire at Arizona State University, and he's one of the researchers who's done this, where you take a bunch of

grad students and you basically just embeds yourselves in a protest. And he told me what he does is have his cell phone up. So it looks like he's talking on the phone when what he's actually doing is recording notes to himself in voicemail about what's happening, what happened when, and how the police and protesters are interacting what kind of like that relationship looks like throughout the evening. Now, as you might suspect, that can end up going poorly for these researchers. McGuire has been shot in the face with a projectile. I'm just speechless. I don't know how to react to that.

Yeah. I mean, he's, I think what's interesting about him is that he is somebody that has really good relationships with the police and he actually does police trainings and he's been trying to convince departments across the country that they need to focus more on de-escalation. He was interviewed by the Washington Post after Saturday night when you had these pretty heavy-handed crackdowns all over the nation talking about how these things that he was seeing really did represent that escalating a force that his research was talking about. And that kind of ties in with some of the stuff that I saw.

You know, we had, my reporting partner and I were threatened with a projectile gun at one point. At another point, we saw video and met some people who had just had some police officers shoot at them while they were on their own porch. And we ended up meeting up with a local newspaper reporter whose window had been shot out by a police projectile. Does the research point to anything that protesters themselves do that might affect everyone's safety? Yeah, I mean, they also say that, you know, protesters pushing into the police's space can do the same kind of thing. You know, it's not that police are the only ones escalating. but what they have found is that police escalation is often a first step towards other groups escalating back and that police have an opportunity to stop that cycle by not escalating from the

beginning. As they say, we are still dealing with COVID-19, but there's also been some concern about whether the protesters and the protests are bringing people too close to get. What do we know about the protests and the pandemic? One of the things that I've been thinking about a lot in this past week is how those first protests on Tuesday here, right after Mr. Floyd's death, people were really working hard to try to make those be COVID aware. You know, people were masked up. They were socially distanced. I had some friends who were at that march and were sending me videos where this crowd, just looked completely massive because it turns out when everybody is six feet apart,

your march goes on just for miles down the road. When they were met at the police station by officers in riot gear and some kind of confrontation began, that pretty quickly shifted from this peaceful march with socially distanced people to officers firing tear gas and projectiles into a crowd in the way that my city councilman who was at that scene called indiscriminate. So the result was hundreds of people coughing, demasking, fleeing, being in each other's personal space in a way that they hadn't been up to that point. That the escalation of force wasn't just about the safety of the officers and the safety of the people and the safety of buildings around them. It was also about how you upping that risk for COVID-19 exposure.

And there's been several articles that came out this past week talking about the way that tear gas can actually up the risk of COVID-19 infection just by itself. Because you're talking about something that induces coughing and heavy breathing, which means more particles in the air that could spread coronavirus around. The New York Times also reported that military research in the past has found that exposure to this kind of gas can up your risk of contracting. a respiratory illness. And I know there are also the arrests where police crowd people together on a street, right, sitting down, waiting to be arrested or even at the police station? Right. We haven't seen a whole lot of that here in Minneapolis, but the videos that I've seen in other

places, it's definitely a technique that is going to force more people closer together. Is there a recipe they're saying? for a pandemic safe protest? I'm not seeing any clear recipes for a pandemic safe protest. What I am seeing is people talking a lot about balancing the risk of contracting coronavirus with the risk of doing nothing

about what they see as police brutality in their community. When the first protests were being put together on Wednesday, I saw people online having these conversations and sort of talking about, you know, how they were going to make sure that people were trying to wear masks and how they were going to make sure that people were trying to stay six feet apart. So it's definitely something that protesters are thinking about, at least here in Minneapolis. Maggie, always a pleasure talking with you. Please, I know, you hear it all the time.

Stay safe. You have our concerns with you. Maggie Kerth, senior science writer for 538 based in Minneapolis. Minneapolis. After the break, as a medical field, dermatology is literally skin deep. We'll talk to a doctor who is working to improve care and diagnoses for people with darker skin. Stay with us. This is Science Friday. I'm Ira Flato. Have you made an appointment to see your dermatologist recently? Maybe get a skin cancer screening or check out that inflammation. If you're a person of color, someone with darker melanin-richs, skin is statistically likely that your dermatologist is not. And while that shouldn't matter, it's also likely that they trained on photos that were more likely to be from light-skinned patients.

And in such an intensely visual field where redness and discoloration are important symptoms, what consequences does this lack of diversity in both practitioners and data have for the patients? My next guest has asked both these questions, and in response, opened one of the few clinics in the country that specializes in patients with melanin-rich-skinned skin, skin of color, the technical term. Dr. Jenna Lester, Assistant Professor of Dermatology, University of California, San Francisco Medical School, and director of their skin of color clinic joins me here. Hello. So what draw of you to open this clinic? A number of factors.

When I was a resident, I would always be struck by the reaction that patients of color would have when I'd walk through the room. They pretty much uniformly would say, wow, I've never had a black dermatologist before. I feel like you're going to understand my skin, especially if it was someone with a hair concern. They would say, you know, dermatologist X told me to use this on my hair and told me to wash my hair every day, something that if you've ever come in contact with a black woman, you know that that's not something that we do. It just, it spurred me to, well, first of all, I realized what a big issue that was and made me want to create a place where these patients felt comfortable. To dermatologists, are they able to recognize the differences in the skin? People have darker skin?

I mean, when you get training, does the training help you? I think the training does help, and I think that's one of the things that I want to focus on is education, because studies have shown that close to half of graduating dermatology residents don't feel comfortable diagnosing skin conditions and skin of color. And I think that has a lot to do with exposure. Part of it depends on where you trained. If you train in an area of the country that's less diverse, as opposed to a place that has a lot of racial and ethnic diversity, you may have had differential exposure to these things in the clinic. And so then you rely more on photographs that you look at from textbooks, et cetera.

So I think that is sort of the crux of the issue. Is there any bias in the photograph? So I have found that there is. We took, along with a group of medical students, took a look at photographs in common teaching textbooks and teaching slide sets and found that about a third of those images were of darker skin tones. And you may think, okay, well, a third, that's probably enough. But if you consider that many dermatologists need to know rashes that they may have never seen in real life, you realize how much more important those photos become. And I would say we need one-to-one representation of every skin condition in every different skin color.

That would be ideal. Why is this training deficiency so important for the patient outcome? Well, there are several disparities in dermatology in general, but in medical, across all specialties in medicine. And I think education on the differences. and what color looks like in different colored skin is really important in addressing those disparities and not contributing to delays in care and making patients feel comfortable and that you're informed and know what you're talking about. How differently do skin conditions present when your skin is darker?

Something like psoriasis, for example. That's a great question. So there's a concept called simultaneous contrast, which it comes from color theory and was first described in the mid-1800s. And that's the concept that color is dynamic. And so color surrounding anything in particular that you're looking at really affects how it hits your eye. And so erythema or redness, inflammation in the skin, when we see it, we describe it as red or pink. And in darker skin, can actually look more what we say in dermatology, violaceous, or purple, sometimes dark blue.

And if your eyes not trained to see that, then you miss it. So it's harder. You really have to be trained to see that. Yes. And I think repetition is the greatest teacher. So if you don't see this over and over and over again in situations where there's time pressure, where you don't have enough information or you have incomplete information, you have to make decisions quickly, this is something that you might miss. Well, so then should people, you know, with darker skin themselves be more cognizant of changes in their skin because they, you know, they might not feel that they need to.

Yeah, I think many are, and I think what I've heard from patients is they come to the doctor and are told nothing's wrong sometimes. I do also think that there is education that we as dermatologists need to give our patients about the fact that, you know, skin cancer, while it's less common in patients with darker skin, still happens. And when patients with African American patients, for example, when they present with melanoma, are more likely to have advanced disease and are more likely to present with nodal metastases or. spread to other parts of the body. Is that because they've waited so long? I think it's, yeah, I think it's because they've waited. Maybe they've been told skin cancer is not something that can happen to you. And in patients with darker skin, these are more likely to happen on areas of the body,

like the palms of the hands or the souls of the feet. Maybe you don't look in those areas as much. I think people think that, you know, if you have a darker skin color, that the melanin protects you. Is that a mythology? That's not a mythology. That's absolutely true. And we see that in the incidence of different skin cancers.

And oftentimes skin cancers that patients of color get are not UV related to UV or sun exposure. But I still think that you have skin, you can get skin cancer. I think that's kind of the bottom line. So you have opened up a clinic. Yes. And do you see people coming to you who are sort of refugees from other doctors or other clinics? Patients do travel from far to come see me, and I think that happens for a number of reasons. They want reassurance that the path that they're on is the right one.

They've maybe had a bad experience, and I think a lot of people are just, they've never, they want their doctors to look like them, I think, in a lot of situations. So it's quite powerful. Is there any part that you see misdiagnosed more often on the body than anything else? You mean any part of the body where there's a misdiagnosis? Face, hair, shoulders. Yeah, I actually see a fair number of patients who come in with issues of hair loss and things that, a particular condition where we can give a patient a name, we can do a biopsy, we can make a diagnosis and start them on the road to treatment. Maybe was brushed off before and said, you know, there's nothing we could really do about this.

So just sort of deal with it. I have a tweet from Chidi who says, are people with darker skin more prone to certain skin problems? If so, what are they? That's an excellent question. And I think largely that's something we're still discovering. There's a condition that provider at UCSF, Haley Nyack, is working a lot on called Hydridonitis Separativa. We think that there are racial, ethnic differences in that particular condition. But a lot of these studies haven't been done, and so we're working to figure that out.

We've talked about skin cancer. or melanoma? Are there any other kinds of skin conditions we're identifying it correctly could be a life or death situation? Yeah. So a particular example that comes to mind is something called toxic epidermal necrolysis. Say that again? Toxic epidermal necrolysis or TEN for short. And this is one of the severe dermatologic emergencies. People think dermatologists don't treat life-threatening conditions. And to the contrary, this is one that dermatologists can have a life-saving impact. And a patient in my medical training, I trained at many different institutions, a patient with darker skin sat in the emergency room for eight or ten hours because

the redness, which can be subtle in patients with darker skin, that's the sort of hallmark feature of this condition, was missed in this person. What about jaundice, right? You're supposed to skin get yellower from jaundice? Could this be missed with people who have darker skin? It could be missed. I think places where you could still look are the sclera, the eyes, the palms of the hands, but oftentimes John just doesn't reach those areas until it's pretty far advanced. Wow, that's interesting. In your clinic, what do you need?

What that you don't have a blank check question? I don't have the real blank check. If you had a blank check and you needed to buy equipment or a better test for something, what do we really need? I think I would need a medical photographer. I need someone who could set up and take photographs of literally. every single thing that I ever saw during the day because part of the huge issue is this disparity is in the existence of photos. People are interested in including these in their talks,

but they don't exist in the numbers side by side with the photos of lighter skin, and we need really good photos. But there are doctors manuals of skin diseases. They're not good enough, is what you're saying. I say they could be better. They could be better. They definitely could be better. And there are atlases of patients with skin of color, but they're separate. And if you're a dermatology resident, say, in San Francisco, who's struggling to pay your rent and also eat and doing all of these other things, buying a separate textbook is really something you can't do. And I think it also signifies that this is not something that should be part of the mainstream of dermatology. We have to have a separate book for it. You need to take an extra step to learn about

this, so it's optional. And you need to collect more data from people. Right. Are they willing to volunteer? I think that's a tenuous question because there's a history. There's a legacy in our country of mistreatment and experimentation that a lot of people remember. And there are some very well-known examples, but I think people also have personal examples where they're hesitant to do that. So if they're hesitant to come to you as a doctor or a dermatologist, they may be hesitant to go to another kind of doctor and miss out on a different disease. Have you ever referred to patient? Oh, all the time. My 10-minute appointments often extend to 20 and 30 minutes when I get into blood pressure control and other things these patients should be doing because they do see me as someone that they want to tell all of their problems to, and I see it as an opportunity. Any interaction someone has with the medical system is an opportunity where they either turn towards care or away from care. And so I see myself as a gateway for a lot of patients. So what do you say to people? We have a large audience. I have 2 million people listening. What's your message to them about going to see that can't all come to your clinic?

What's your message? Or to doctors who might be listening, we need to have more clinics of your type opening? I think that doctors should, we all have a responsibility to care for all patients. Sure, maybe black patients or patients of color want to see me. There's not enough of me or there's not enough of doctors that look like me. So as a medical community, I think we all have a responsibility to fill the gaps in our knowledge and to educate ourselves. This is a field of lifelong learning. It never stops.

So you have a responsibility to all of your patients to do this so that you can adequately diagnose them, treat them, give them the right medications that work for their particular condition. Amara Flater, this is Science Friday from WNYC Studios. Talking with Jenna Lester, assistant professor of dermatology. at UC San Francisco Medical School. Is this a topic of discussion at medical school conventions or dermatology conventions? Do they doctors realize this? I think this is something that more and more people are realizing. And it's catching more traction.

I think as we talk about diversity in the specialty of dermatology, dermatology is the second least diverse specialty. So I think this sort of goes hand in hand with the issues and the conversations that happen around diversity of our workforce. Because I know of cases where there have been cases of melanoma, for example. And I know people who have been diagnosed with melanoma, but it was not the typical, you know, five, six, seven variations that you're supposed to look for. It was something totally different.

And when I talked to a doctor about this, he says, you know, we couldn't list everything that will show up in patients. So we just list the most common types. It seems like what you're saying is the same sort of thing that's happening here. Yeah, I think education is central to this because what I think of when I diagnose melanoma often, patients say, oh, this one has changed. And these are often patients who have been told since they were younger, skin cancer is something you should get. You should wear sunscreen. You should stay out of the sun.

These are the signs that you look for. So when subtle changes are something that's picked up on, you have to think that education is at the basis of that. Yeah. Let's see if we have time for a call before we go. So, Octavia in Decatur, Alabama. Hi, welcome to Science Friday. Hi. How are you?

You all. Fine. Go ahead. Okay, so my question is, well, I have a doctor, a dermatologist, that's Indian, and his skin is really dark. And a lot of the patients that I see coming in and out of his office are darker skin, you know, people up in Indian descent. descent and African Americans. So I'm just kind of wondering how closely related are our skin makeup? Because I know with me, he always hits the nail on the head. So is our skin makeup related? That's a really good question. And I think overall there are more similarities than

differences. A lot of what a lot of the differences have to do with skin tone. And so in dermatology, You have something called the Fitzpatrick scale that was developed as a way to determine someone's likelihood of developing skin cancer, but has also become a proxy or a stand-in for a skin tone. And so it goes from one to six, and six is the darkest, and one is the lightest. And so, you know, there are people of different ethnicities that would fit into the same skin tone. So I think a lot of that has to sort of draws the similarities between the skin as well. So where do you professionally go from here? Oh, professionally.

You can expand the clinic? So research is something that I'm a research program is something that I'm developing now. I'm also developing curriculum, trying to teach the next generation of physicians how to care for patients with all different skin tones. I think education is the way to have sort of a reverberating impact, since, as I said, I don't think there will ever be enough doctors of color to see all the patients of color that want to see them. We hope we've made a dent in the education process today. Yes, I hope so, too.

Dr. Jenna Lester, assistant professor of dermatology at the University of California, San Francisco a medical school. Thank you. Thank you for having me. Thank you for having time to be with us today. Let me just tell you that one of the things we love most about Science Friday is creating live radio. But two months ago, along with everyone else, we've had to adapt to the pandemic. So we moved the show from our studios into our Homes, our SciFri Home Edition. And as you know,

working from home yourselves, producing a radio show from home requires a bit of, shall we say, creativity. We've been building blanket fort sound booths, creating events online. And I've had to time my interviews around the racket of my neighbor's lawnmowers and leaf blowers. Producer Christy Taylor recounts how she went from one place to another in her apartment looking for the most soundproof room. And my snug basement bedroom is actually the quietest place for recording. The closet is bad. I check that.

When our neighbor runs the water, you can hear all of the pipes gurgling. You can take a peek behind the scenes to check out how we're putting together Science Friday's home edition at Science Friday.com slash staff. stories. And of course, due to social distancing, this hour is pre-recorded. We won't be taking your calls, but that doesn't mean we don't have some really great stuff coming up after the break. For example, we'll talk about how chemistry might be the key ingredient to your perfect cup of coffee. Get your beans ready and stay with us. We'll be right back after the break. This is Science Friday. I'm Ira Flato. Is making your morning cup of coffee like a sacred

ritual, carefully grinding the beans just a certain way, depending on if you're having an espresso or a drip. Next, you boil the water to the exact temperature, not too hot. And finally, you brew. Are you going to steep it, pour it over, or leave it up to the coffee maker? There's a lot of details that go into coffee. But what is the science going on behind those steps? Because as we know, a dose of science can make most things better and your coffee more consistent. A team of researchers used math models to figure out the optimal grind size to get the most out of your espresso poll. The results were published in the journal Matter. Christopher Hendon is one of the authors on that study, an assistant professor of chemistry at the University of Oregon in Eugene.

He's here to talk about these results and to talk coffee science. Because we know the best part of waking up is having cancer. chemistry in your cup. Welcome to Science Friday. Hi, Ira. Thanks for having me. I know you spend a live. I've read all these papers you've written. You spend a lot of time on coffee chemistry, don't you? That's right. You know, I like to think of it as one of my more sophisticated scientific outreach programs. So I know you're working on building new kinds of materials, right? What does that have to do with coffee? Well, a lot of the chemical principles that I use in my day-to-day lab with my graduate students and undergraduates here at the University of Oregon are

Based on this or are an application of the same principles that we're using in the coffee science, what I study here at UO is related to energy materials, and more often than not, in energy, there is transfer of mass moving from one place in space to another. And you can actually think of that problem is the same problem when you're modeling or thinking about how you extract coffee. Let's get into the grind. Your study looked at getting a consistent shot out of your espresso pole. an espresso is right, usually brewed with a very fine grind size, but you found something different. Right. So currently, the average way of producing espresso is to grind very, very fine, and use something like 20 grams if you're in the United States, Australia, Germany, etc. And move about 40 to 50 milliliters of water through this 20 gram puck of coffee.

On average, you're going to extract something like about 20% of the mass. So 80% of the mass is going to be wasteful. and that 20% of the masses ended up solvated in the cup and hopefully tastes good to you as the end user. When we were examining building a model, we thought, well, okay, the extraction must be related to the surface area available from grinding the coffee. And so as we developed our model, we realized that as you grind finer,

you expose more surface area. And so one would then expect for the same amount of coffee and the same amount of water that you should be able to extract more, proportional to the surface area. But in reality, we found that actually grinders produce very small particles and very relatively large ones as well. And these two particle sizes coexist.

And when you produce a critical number of these small particulates, they tend to clump. Now, at certain grind settings, sufficiently fine. You'll find that the clumping actually causes the water to percolate through that bed in an in homogeneous or uneven way. And it is at these grind settings that we also happen to find. are widely used in the production of espresso. And so the conclusion from the, or at least when examining the status quo, is that conventional espresso today is used with an uneven exposure of the coffee to water, resulting in variation

in flavors that are not attributed to the human, but rather attributed to the method in which we produce espresso right now. All right. Let's say I want to make my own espresso, or I just want to do it in the coffee maker. How do I decide what's the best grind for me? because I can go to the supermarket and grind it to different consistencies. That's right. What can I do at home to make sure I'm getting the best grind?

And how to you experiment with that? That's right. So this is sort of touching on a flavor perception problem as well. So typically we would advise to start with coarsely ground coffee. And now by and large, when I mean course here, I don't mean French press course. I still mean an espresso grind. It's still quite fine to you, the human eye. you start grinding with that dose and you're going to brew some of coffee and if it tastes a little thin

and a little weak and perhaps a little too acidic and not enough chocolate then you want to grind a little finer and now you're going to progress doing this to a point but at some point you're going to notice that the concentration of the coffee in other words the strength is beginning to decrease and the flavor intensity is beginning to increase in a negative way and at this point you know you've gone over the hill and you're no longer evenly extracting from your coffee you're in in the side of uneven or in homogeneous extraction, and you need to back off from there. Once you're at that point, that's where the real fun begins. Wow, that's great.

I can experiment with that because I'm a geek and I can become a coffee geek, I think. One thing I've heard controversially over the years, and we've talked coffee for almost 30 years around Science Friday, is people have different opinions about how to best store their coffee. Right. In the freezer, in the refrigerator, on the counter. What have you found? So actually in 2016, I actually studied this, and we published that in an open access journal.

One of the key things with coffee is that it begins its life as a seed from a plant. So it has about 11.5% moisture contained within. And once you roast it, you're going to drive off almost all of that water, if not entirely all of it, and make it completely anhydrous. And so, obviously, this material is going to be much more dry than the atmosphere that it's surrounded by. And so it's going to want to condense water within. So the first and most important thing is to make sure the, that you keep the coffee air-free, but only because you're trying to keep away water or moisture.

However, we're then put in a bit of a pickle because the erinius equation tells me that if I cool things down, most rates of reactions go slower. So if I want to preserve coffee for a long time, I want to keep it as cool as possible, perhaps in the freezer. But the problem with a freezer, of course, is it's pretty wet. So you're stuck in this sort of a in the middle here, a push-pull. And so what we actually end up recommending people do is to keep, to keep it. keep it in the freezer, but in a vacuum-sealed type vessel.

You see this occurring more and more, and at the moment, we don't have a polymer, the type of plastic bag, perhaps, that you would be able to reuse. So it's somewhat wasteful at the moment. And so, therefore, you only see this in very special cases where you're trying to preserve very high-value types of coffee. Why couldn't I put it in a jar and put the lid on time? That works perfectly fine. But if you open up the jar while the coffee is still cold in the room in the atmosphere, then you're going to condense water from the atmosphere on. onto the surface and inside those beans. And so the more times you do that, you know, progressively,

you're going to have more and more water being condensed within that vessel. So it's a tricky problem. Indeed, it is freezer burn, yeah. And you don't want your coffee smelling like fish sticks. That's true. Now, when I take the coffee out to grind it, do I grind it frozen? I want to grind it frozen that way? So we've actually found that temperature does directly affect the size of the smallest particles

in the grind. And it happens to be favorable. So actually, as you cool down, cracks propagate through materials more quickly and result in more unified particle sizes. And so these small particulates actually are formed and are very reproducible when we cool this coffee or cool any material for that matter. And so we do recommend actually grinding it frozen. And then once you expose the frozen grounds to hot water, they very quickly equilibrate to the temperature of the water. Brewing is as poor normal. All right, let me get to the water because I found something amazing in your research,

and that is we should not be using distilled waters, reverse osmosis, whatever. We should be using hard water when making coffee. Yeah, so this language of soft and hard is complicated because it's very easy to define soft, you know, water that doesn't have very many minerals dissolved within. But hard water is simply defined as water that contains lots of minerals. but it depends on their identity. So instead of talking about calcium and magnesium, and they are important,

the main mineral we're trying to avoid using is bicarbonate, because bicarbonate creates a buffer to try and stabilize the pH. And coffee itself is acidic. In fact, we like the acids in coffee, even if we don't perceive them necessarily as the peel of a lemon or whatever, we still enjoy the acids

because they taste like sweetness and acidity. So we simply don't want to use water that contains high levels of bicarbonate, but if we could have other minerals there that did not buffer acids, then that would be ideal. Doesn't water softener have bicarbonate in it? So typically a water softener actually is exchanging out calcium and putting in sodium. And so why it's softening the water is it's preventing calcium and carbonate to coexist forming limescale.

But it's not actually killing the bicarbonate. It's simply actually removing the thing that we actually want for coffee extraction, which is calcium. Wow. I'm just, you know, because I always thought the pure of the water. So, well, let me go back to that. Does that mean, you know, we here in New York, we talk about we take our coffee seriously, we take our bagels seriously. Very. I mean, could that be the same kind of watery thing going on in what makes a bagel better than what makes one coffee better? Interestingly, there is a company that has re-created the chemistry of New York water for making bagels.

So people have caught onto this idea already. The reason that we were talking, and you first mentioned, the idea of using soft or distilled water as being a positive thing for coffee, is not because it's somehow, you know, that's what's taught. It's not because it's somehow better or worse. It's because it doesn't have bicarbonated it. That's just a guarantee. So at least you know you're going to get some of the positive flavors out. But when you're looking at New York, tap water or municipal water provided wherever in the state of New York, You're right. It does impart some sort of terois, some chemistry related to New York's specific water, and that has enabled the production of things like bagels and exceptional coffee in the city.

See, you've just justified what we like to say here in New York. Thank you for that. You're welcome. Okay, let's go back to brewing methods now. I'm going to move on through because there's a lot of interesting things. There's a trend now at coffee shops where you can choose your brew method, right? You're pour over, you're steeping. How do these methods extracts? the coffee molecules out differently, and how do you choose which one is right? Yeah, that's extremely complicated. So shops that offer a wide variety of brew methods are really working hard to present that as an option for the customer. More often than not, you'll find maybe one or two choices for a given coffee. Typically, baristas, shop owners, roasters, home enthusiasts are making decisions about how they're going to extract that coffee based on primarily three things. First of all is the

roast degree. So it is typical in the coffee industry to find darker roasted coffee being used in espresso. And the reason is, is that you are going to sort of moderate some of the acids that exist in the green bean so that you're not going to get something that's extremely acidic and very hard to enjoy. And so you find the dark roasted coffee are more prevalent, and that pretty much summarizes the Seattle coffee scene at places like Italy and so forth. The next thing that practitioners typically want to consider is the concentration in which they want to to consume the coffee. So if you make a filter coffee, you're going to use 20 grams of coffee, say, but you might then pour over 250 milliliters of water on it. And that makes a much more dilute

beverage than if you were to use 20 grams of coffee and use only 40 milliliters in an espresso machine. And so indeed, it is coffee specific as to whether you want to taste the concentrate or the stretched out version. Let me just remind everybody while we're having our next cup of coffee. I'm Ira Plato. This is Science Friday from WNYC Studios, talking with Christopher Hendon, Assistant Professor of Chemistry at the University of Oregon and Eugene. Would you be a coffee geek, would that be the correct classification or coffee enthusiasts? I think now I'm a coffee researcher, I guess. Oh, okay. Yeah. Do you have your favorite method of brewing, brewing method that you use?

Yeah, so in my office, when we have academic visitors, I love to present them a coffee that has unusual flavors and so forth. But I typically find the most reproducible way for me to do that in my hands is a pour over method, something like a V-60 or a Kalita wave or something like this. But if I were to go out and enjoy a coffee, by far my favorite format is to try the coffee both as an espresso and with an espresso with a little bit of milk. And I call that a one-and-one, where you have the same shot split in half. That way you know you're getting the same espresso, but you can see how the flavors translate when you add milk. Is that called Caféole in France? The Cafe Ole is indeed, yeah, you're right. It's coffee plus milk, but probably a bit bigger than the old espresso and cortado combo I'm talking about.

I remember growing up with a percolator. Oh, yeah. How does that work differently than the way we brew coffee now? So it's interestingly, it's becoming more popular once again. There's been a resurgence in the percolator. Yeah, it's bad. Going into my basement. Yeah, well, it's probably worth a lot of money now.

The inventor actually recently passed away, and there was a big ceremony in Italy for this. It was, you know, it was essentially a party because indeed the percolator was sort of one of the earliest embodiments of the portable espresso machine. In the sense that you start with water at the bottom, you boil it, you create a critical pressure of steam. And that steam pressure that is then forced through the puck of coffee, that gives you an extraction that is only enabled by having that addition of pressure. and then you can get a very concentrated beverage out of it. And so actually a percolator is essentially a portable espresso machine without all the bells and whistles. Yeah, but it also recycles the coffee over and over again, doesn't it?

Goes through the basket, goes back up again. Yeah, there is a little – so it depends on the design. Of course, there's ones that look like a fractional distillation column where once the water is sufficiently boiled and steam passes through the puck, it then goes through this sort of cap and can no longer recirculate. So it depends on the embodiment. but you're right. You could.

That's the vacuum one, is it? With the big bowl on the top and the pot on the bottom goes up through? Yeah, so I think the one I'm referring to specifically is sometimes we're called the mocha pot. And the percolator coffee is, it does have this, it's more or less a mocha pot with a recycling feature. But, you know, either of them are having a resurgence because of its portability. So it really is. It's not the machine we think it is. Something a little more complex.

That's right. And, you know, just for someone who grew up with a percolator as a teenager, is something also, it helps your body. You feel good when a big pot of coffee comes over, you know, is the experience that you don't get from a little pourover in a cone. I'm sorry. Yeah. So in the percolator sense, you're thinking, in this case, we're referring to like a Mr. Coffee type product, one of these big pots that you find at the, oh, I see. So when I think of the percolator, I was referring more than mocha pot. I'm sorry.

No, no, I'm talking about the percolator that, you know, is the stainless steel thing you plug into the wall. Yeah. That's the one I'm referring to. Yeah, yeah. So you're right. You know, there's something that still, you know, it still resonates with me as well. And I go into a diner, for example, and I see this big pot of coffee sitting on top of the brewer. And, you know, it means it's going to be a good day.

I'm going to end it there because that's my cup of coffee also. That's the coffee kind of coffee I like. Thank you very. Thank you very much, Christopher. My pleasure. Absolutely. Enlightening us about coffee and everything we needed to know. Christopher Hendon, Assistant Professor of Chemistry at the University of Oregon, and Eugene. One more thing before we go.

We know you're listening to Science Friday because you love science and you know it's value in your everyday life. But I want to remind you, no, I need to remind you that your local public radio station is the one bringing you this show today. So please consider making a donation to your local station. Their work is underappreciated and very, very important. Charles Berkwest is our director. Our producers are Alexa Lim, Christy Taylor, Katie Feather, and Kathleen Davis, B.J. Leederman composed our theme music. And if you missed any part of this program or you would like to hear it again, please subscribe to our podcasts or ask your smart speaker to play Science Friday. Have a safe weekend. We'll see you next week. I'm Ira Flato.