The Science of Coffee

The Speed of Heat: How to roast more coffee, faster!

To roast coffee faster, you need to turn up the heat….right?
 
No! 
 
In this episode, we explore the three powerful methods of heat transfer that revolutionised roasting. We’ll journey from humble beginnings—when roasting three kilos took half an hour—to machines that now roast hundreds of kilos of coffee in the time it takes you to boil a kettle. 
 
But beans roasted at lightning speed look strange, and taste… well, you’ll find out. Join us as we test-drive an industrial tangential roaster where first crack remind me of fireworks crackers. 
 
We also see the whale-sized roaster so massive it’s worth you a Guinness World Record. 
 
We have the technology today to roast coffee faster than ever, so why aren’t we all roasting at recording-breaking speeds?
 
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Check out the Probat roasters mentioned in this episode:
 
Emmerich Spherical Roaster - "Pink Hydrant"
Large ball roaster - “Sputnik in a pizza oven”
G45 early drum roaster - “Old school steam train” 
Early tangential roaster
Sample tangential roaster - "Shoebox"
Neptune 4000, the largest drum roaster in the world! - "The whale"
 
And there are lots of other specialty roasters from Probat I didn't have time to showcase, including their new hydrogen powered roasters. See them all for yourself!.
 
Theodor von Gimborn's wikipedia page
 
 
Go deeper into the science of roasting
 
Read Mark Al-Shemmeri’s coffee roasting blog
Do a Certificate of Advanced Studies with the Coffee Excellence Centre
Explore Barista Hustle's online roasting learning
Learn more from Morten Münchow and his coffee roasting courses
Read Morten’s paper in collaboration with the University of Copenhagen on Roasting Conditions and Coffee Flavour
Follow Filter Stories on Instagram for my infographics
Learn more about first crack on my episode Coffee Roasting, Part 1: How heat transforms coffee beans
 
 
Season 3 is made possible by these leading coffee organizations:
 
The Coffee Quest | BWT | TODDY | Algrano | Probat
 

Coffee Roasting: How baby plant food transforms into delicious coffee flavours

A mother coffee plant gifts its baby everything it needs to grow—a green seed packed with food. But when we roast coffee, we hijack that gift and turn it into something else: flavor.
 
But what is flavor, at a microscopic level? What actually happens inside the bean when heat meets those nutrients?
 
In this episode, we shrink down to witness the Maillard reaction up close—a wild chain of molecular collisions that transforms baby plant food into aromas we adore. 
 
Grab your popcorn - you’re getting a front row seat at the wildest chemistry show in coffee. 
 
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Please spread the word about The Science of Coffee!Leave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple Podcasts
Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter
Ethiopian forest sounds curtesy of George Vlad. Hear more nature sounds here.Explore Probat's roasters
 
 
Go deeper into the science of roasting
 
Do a Certificate of Advanced Studies with the Coffee Excellence Centre
Grab a copy of Anja Rahn's upcoming book on coffee science through her Instagram
Explore Barista Hustle's online roasting learning
Learn more from Morten Münchow and his coffee roasting courses
Read Morten’s paper in collaboration with the University of Copenhagen on Roasting Conditions and Coffee Flavour
Follow Sebastian Opitz on LinkedIn
Follow Filter Stories on Instagram for my infographics
 
 
Season 3 is made possible by these leading coffee organizations:
 
The Coffee Quest | BWT | TODDY | Algrano | Probat
 
 

Fruit juice or creamy almonds? Your guide to controlling cold brew flavors

When I started making cold brew this last year, I treated it like hot brew filter coffee. But no matter how I adjusted the grind or tweaked the brew time, I hardly got any differences in flavor…
 
Then it hit me: cold brew isn’t just a slower hot brew—it’s a completely different game with its own rules!
 
In this episode, I speak with leading coffee researchers who break down the microscopic dance between water and coffee that explains why cold brew plays by its own playbook.
 
And I bring you in on the brewing secret that can turn your brews from fruit juice to nutty creaminess. 
 
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Please spread the word about The Science of Coffee!Leave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple Podcasts
Discover how I make these Filter Stories episodes by subscribing to my Substack newsletterExplore TODDY’s cold brewing kits
 
 
Go deeper into the science of cold brew
 
Do a Certificate of Advanced Studies with the Coffee Excellence Centre
Read Jiaxin (Jessie) Liang’s equilibrium extraction SCA 25 article and her published article
Discover all of UC Davis' cold brew research through the Coffee Science Foundation
Learn how to do a cold brew cupping with Toddy
Follow Filter Stories on Instagram for my infographics
 
 
 
Season 3 is made possible by these leading coffee organizations:
 
The Coffee Quest | BWT | TODDY | Algrano | Probat

Hot vs Cold: The science behind temperature and taste

For years, I used cold brew as a last resort—the only brew method to tame dark, oily beans that were too bitter for hot water. 
 
Then one day, I took a chance on a Guatemalan Gesha and brewed it cold. The result? A massive explosion of florals I’d never tasted before. That single cup sent opened my eyes into how extraordinary cold brew can be.
 
In this episode, I speak with world-leading coffee scientists who explain why brewing with cold water tastes so different from chilled hot coffee. 
 
You’ll learn how certain flavors leap into your cup (and how others mysteriously vanish) when you lower the brew temperature.
 
You’ll also discover there are hidden “cold brew gems” in beans you thought you knew. So before you grab the kettle, consider this: sometimes all you need is cold water.
 
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Please spread the word about The Science of Coffee!Leave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple Podcasts
Discover how I make these Filter Stories episodes by subscribing to my Substack newsletterExplore TODDY’s cold brewing kits
 
 
Go deeper into the science of cold brew
 
Do a Certificate of Advanced Studies with the Coffee Excellence Centre
Listen to my episode on Coffee Extraction for insights into how polarity affects flavor extraction
Read the UC Davis cold brew vs chilled hot brew study
Listen to my episode on 'How to think like a scientist'
Learn how to do a cold brew cupping with Toddy
Follow Filter Stories on Instagram for my acidity infographic
Go deeper into Paul Breslin's work at the Monell Chemical Senses Centre
Discover all of UC Davis' cold brew research through the Coffee Science Foundation
 
 
Season 3 is made possible by these leading coffee organizations:
 
The Coffee Quest | BWT | TODDY | Algrano | Probat

Introducing: Season 3 of The Science of Coffee

We’re back with another series of The Science of Coffee—and this time we’re diving even deeper into coffee’s hidden microscopic secrets!
 
Over the past year, narrative audio producer and coffee professional James Harper has scoured academic journals, ventured deep into coffee farms, and conducted bold tasting experiments.
 
Now, he’s weaving those discoveries into captivating audio stories that reveal why coffee tastes the way it does—and how we can make it taste even better.
 
In this new series, you’ll learn about cold brew extraction science, explore innovations in roasting, and follow the shifting business models that shape farmers’ livelihoods. You’ll also take a journey through commodity vs. specialty supply chains and examine the historical, sociological, and philosophical perspectives that define what “specialty coffee” truly means.
 
Press the “Subscribe” button so you don’t miss an episode!
https://bit.ly/3TdDnHO
 
For more coffee science and behind-the-scenes content, follow James on Instagram @filterstoriespodcast.
https://bit.ly/2Mlkk0O
 
The Science of Coffee is a spin-off series from James Harper’s documentary podcast, Filter Stories. 
https://bit.ly/3ajoT5e
 
Season 3 is made possible by these leading coffee organizations:
 
The Coffee Quest | BWT | TODDY | Algrano | Probat

Freshness and Grinding, Part 2: How grinders work deep inside

Deep inside your coffee grinder, tiny changes can have massive consequences. This episode takes you deep inside Mahlkönig’s grinders to show you how coffee is ground and the importance of particle sizes on flavour. If you’re a home coffee lover, you could easily spend thousands of dollars on your coffee grinder. But after diving deep into the R&D of grinder manufacturing, I learned that after a certain point spending more probably won’t produce a better tasting cup of coffee for you! ---------Please spread the word about The Science of Coffee! Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter. Write a review on Apple PodcastsFollow me on Instagram and tag me in an Instagram storyLeave a 5 star rating on Spotify Explore Mahlkönig’s range of world leading grinders, trusted by baristas globally. Go deeper into the world of grinding Take Barista Hustle’s Advanced Espresso courseLearn from Lance Hedrick where the sweet spot is for buying a coffee grinderGet super nerdy with Jonathan Gagné’s writings on grindingRead up on Samo Smrke’s work on coffee fines Connect with my very knowledgeable guests Arnaldo Rodrigues - LinkedInLuca Lange - LinkedInChris Meier - LinkedInDario Burger - Instagram The Science of Coffee is made possible by these leading coffee organisations: BWT Water and MoreMarco Beverage SystemsROESTSustainable HarvestMahlkönig The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories Subscribe to A History of Coffee podcast

Freshness and Grinding, Part 1: Protecting your coffee’s flavours

For your coffee to taste its best, it’s crucial you buy fresh roasts and grind fresh.….….Or maybe not. When I began creating this episode, I was convinced that ‘fresh is best’. But, after delving into the science of coffee freshness, I don’t believe that anymore. This episode goes deep into how diffusion and oxidation changes a coffee’s flavours.You’ll learn what it takes to store your coffee grounds unbelievably well. So well, that if you do it right, you will struggle to taste the difference between two month old coffee compared to those same beans freshly ground!But here’s the weirdest thing: Maybe, just maybe, you will prefer old coffee more than the fresh stuff.----------Please spread the word about The Science of Coffee!Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter. Leave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple PodcastsExplore Mahlkönig’s range of world leading grinders, trusted by baristas globally.Dive deeper into the science of coffee freshnessDo a Certificate of Advanced Studies with the Coffee Excellence CentrePick up a copy of the SCA’s Coffee Freshness HandbookConnect with my very knowledgeable guestsSamo Smrke - Instagram19 Grams Coffee Roasters in Berlin - InstagramArnaldo Rodrigues - LinkedInThe Science of Coffee is made possible by these leading coffee organisations:BWT Water and MoreMarco Beverage SystemsROESTSustainable HarvestMahlkönigThe Science of Coffee is a spin-off series from James Harper's documentary podcast Filter StoriesSubscribe to A History of Coffee podcast

What Is Good Science? Part 2: How to think like a scientist

In the last episode, I discovered that rinsing my Chemex filter papers was a waste of time! As a result I’ve managed to claw back over seven days of my life left on earth. But why stop there? The coffee industry is full of elaborate ways of brewing and savouring coffee: fancy drippers, cold metal balls, “slurp-able” cupping spoons.These are very fun, but how many of them actually affect the flavour of our coffee?I fear elaborate coffee gear is wasting our time and money. They're distracting us from the existential crises in coffee that actually require all our attention now. For example, the issue of farmers who grow delicious coffees quitting the business because it’s just getting too hard. But to figure out whether a popular new coffee tool was actually waste of time or not, I needed to think like a scientist. This episode is the journey I went on to rewire my brain: I had to learn what good evidence looks like, what to do if I can’t find good evidence, and why it’s important to focus mostly on experimental results while resisting the allure of a compelling theory. Please spread the word about The Science of Coffee!Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter. Leave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple PodcastsDiscover this episode’s sponsor BWT’s water filtration products. I use their Penguin magnesium filter cartridges and cafes can use their BestAqua ROCDive deeper into the science of slurping, water and Signal Detection TheoryDo a Certificate of Advanced Studies with the Coffee Excellence CentreRead Georgiana’s paper on soup slurpingLearn more about Signal Detection TheoryExplore BWT White Paper on the effects of magnesium (German)Browse Christopher Hendon’s book Water for Coffee Take Barista Hustle's Water course Watch James Hoffman's water videoConnect with my very knowledgeable guestsMorten Munchow - Coffee Mind websiteJeremy Nelson - LinkedInSamo Smrke - InstagramGeorgiana Juravle - Google ScholarYoung Baek - InstagramFrank Neuhausen - LinkedInSergio Barbarisi - LinkedInAlessandro Genovese - LinkedInThe Science of Coffee is made possible by these leading coffee organisations:BWT Water and MoreMarco Beverage Systems ROEST Sustainable Harvest MahlkönigThe Science of Coffee is a spin-off series from James Harper's documentary podcast Filter StoriesSubscribe to A History of Coffee podcast

What Is Good Science? Part 1: How to brew coffee like a scientist

Should you rinse your filter paper before making a filter coffee? Almost everybody in coffee internet says you should. But what if most of coffee internet was wrong?In this episode, I show you how I try to answer this question like a professional sensory scientist would. It’s hard. It’s frustrating. But ultimately, it’s worth it because I end up saving seven days of my life left on earth!Please spread the word about The Science of Coffee!Discover how I make these Filter Stories episodes by subscribing to my Substack newsletterLeave a 5 star rating on SpotifyFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple PodcastsBring out vibrancy in your coffee with BWT’s magnesium water filters for the home and cafeDive deeper into sensory science methodologiesTake Becky Bleibaum’s free introductory sensory science course! Set up a triangulation yourself with DragonflySci’s worksheetsUnderstand Rose Marie Pangborn’s three step process better with Morten Münchow (“Pangborn’s Razor”)Do a Certificate of Advanced Studies with the Coffee Excellence CentreConnect with my very knowledgeable guestsMorten Munchow - Coffee Mind websiteBecky Bleibaum - LinkedInSamo Smrke - InstagramSophie Vo - LinkedInThe Science of Coffee is made possible by these leading coffee organisations:BWT Water and MoreMarco Beverage SystemsROESTSustainable HarvestMahlkönigThe Science of Coffee is a spin-off series from James Harper's documentary podcast Filter StoriesSubscribe to A History of Coffee podcast

Organic Coffee, Part 2: Why don’t we see more organic coffee farms?

Farming coffee organically is amazing because soils are more alive, birds and insects are more plentiful, farmers avoid getting sick with agrochemicals. But, if it’s so great, why is less than 10% of the world’s coffee grown organically?The fact is, going organic is hard. Much harder than growing coffee conventionally. In this episode I show you the story of one of Central America’s most successful organic coffee cooperatives, RAOS, and the four big hurdles that stood in the way of their early founders who all dreamed of converting their farms to organic.This story changed my understanding of farming and is now the reason I choose organic specialty coffee whenever I can. Please spread the word about The Science of Coffee!Discover how I make these Filter Stories episodes by subscribing to my Substack newsletterFollow me on Instagram and tag me in an Instagram storyWrite a review on Apple PodcastsLeave a 5 star rating on SpotifyDive deeper into organic coffeeLearn more about Sustainable Harvest’s Most Valuable Producer programme, their cupping app Tastify, and explore their range of certified organic and Fairtrade coffeesExplore RAOS (Cooperativa Regional Mixta de Agricultores Organicos de la Sierra)'s story for yourselfAre you a coffee farmer? Get in touch with Lalo Perez VaraonaConnect with my very knowledgeable guestsLalo Perez Varaona - LinkedInJorge Cuevas - LinkedInAndrea Futterer - GEPA websiteOsman Contreras - LinkedInRoberto Rene Gonzales - Farm websiteThe Science of Coffee is made possible by these leading coffee organisationsBWT Water and MoreMarco Beverage SystemsROESTSustainable HarvestMahlkönigThe Science of Coffee is a spin-off series from James Harper's documentary podcast Filter StoriesSubscribe to A History of Coffee podcast