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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Leave a 5 star rating on Spotify
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Explore 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

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.

 

---------------

 

Please spread the word about The Science of Coffee!

Leave a 5 star rating on Spotify
Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts

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Explore 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

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

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! 



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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 Podcasts
Follow me on Instagram and tag me in an Instagram story
Leave 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 course
Learn from Lance Hedrick where the sweet spot is for buying a coffee grinder
Get super nerdy with Jonathan Gagné’s writings on grinding
Read up on Samo Smrke’s work on coffee fines


Connect with my very knowledgeable guests 

Arnaldo Rodrigues - LinkedIn
Luca Lange - LinkedIn
Chris Meier - LinkedIn
Dario Burger - Instagram


The Science of Coffee is made possible by these leading coffee organisations: 

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig



The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

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 Spotify
Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts

Explore Mahlkönig’s range of world leading grinders, trusted by baristas globally.



Dive deeper into the science of coffee freshness

Do a Certificate of Advanced Studies with the Coffee Excellence Centre

Pick up a copy of the SCA’s Coffee Freshness Handbook


Connect with my very knowledgeable guests

Samo Smrke - Instagram
19 Grams Coffee Roasters in Berlin - Instagram
Arnaldo Rodrigues - LinkedIn


The Science of Coffee is made possible by these leading coffee organisations:

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

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!

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Leave a 5 star rating on Spotify
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Write a review on Apple Podcasts

Discover this episode’s sponsor BWT’s water filtration products. I use their Penguin magnesium filter cartridges and cafes can use their BestAqua ROC


Dive deeper into the science of slurping, water and Signal Detection Theory

Do a Certificate of Advanced Studies with the Coffee Excellence Centre
Read Georgiana’s paper on soup slurping
Learn more about Signal Detection Theory
Explore 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 video


Connect with my very knowledgeable guests

Morten Munchow - Coffee Mind website
Jeremy Nelson - LinkedIn
Samo Smrke - Instagram
Georgiana Juravle - Google Scholar
Young Baek - Instagram
Frank Neuhausen - LinkedIn
Sergio Barbarisi - LinkedIn
Alessandro Genovese - LinkedIn


The Science of Coffee is made possible by these leading coffee organisations:

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

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 newsletter

Leave a 5 star rating on Spotify
Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts

Bring out vibrancy in your coffee with BWT’s magnesium water filters for the home and cafe


Dive deeper into sensory science methodologies

Take Becky Bleibaum’s free introductory sensory science course! 
Set up a triangulation yourself with DragonflySci’s worksheets
Understand Rose Marie Pangborn’s three step process better with Morten Münchow (“Pangborn’s Razor”)
Do a Certificate of Advanced Studies with the Coffee Excellence Centre


Connect with my very knowledgeable guests

Morten Munchow - Coffee Mind website
Becky Bleibaum - LinkedIn
Samo Smrke - Instagram
Sophie Vo - LinkedIn


The Science of Coffee is made possible by these leading coffee organisations:

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

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 newsletter

Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts
Leave a 5 star rating on Spotify


Dive deeper into organic coffee

Learn more about Sustainable Harvest’s Most Valuable Producer programme, their cupping app Tastify, and explore their range of certified organic and Fairtrade coffees

Explore RAOS (Cooperativa Regional Mixta de Agricultores Organicos de la Sierra)'s story for yourself

Are you a coffee farmer? Get in touch with Lalo Perez Varaona


Connect with my very knowledgeable guests

Lalo Perez Varaona - LinkedIn
Jorge Cuevas - LinkedIn
Andrea Futterer - GEPA website
Osman Contreras - LinkedIn
Roberto Rene Gonzales - Farm website


The Science of Coffee is made possible by these leading coffee organisations

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

The world’s farming soils are deteriorating quickly.

Conventional coffee farming where plants are grown using agrochemicals allowed farmers to reap huge harvests these last 70 years. But these agrochemicals have been at the expense of soil health.

I travel to Honduras to explore a potential solution: organic coffee farming.

Come with me as I show you the organic farming tricks of Don Rufino, one of the region’s leading organic farmers.

He nurtures the soil around his coffee trees using mountain microorganisms, a huge diversity of shade trees, attentive tree pruning, and very funky batches of homemade bug spray.

The results speak for themselves: when I pick up a handful of his soil, it is moist, dense and writhing with life.

Could these cultivation techniques be the answer to the coffee world’s declining soil health?


Please spread the word about The Science of Coffee!

Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter!


Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts
Leave a 5 star rating on Spotify



Dive deeper into organic coffee

Explore Sustainable Harvest’s range of certified organic and Fairtrade coffees
Are you a coffee farmer? Get in touch with Lalo Perez Varaona
Check out Don Rufino’s organic cooperative, RAOS


Connect with my very knowledgeable guests

Lalo Perez Varaona - LinkedIn
Tommie Hooft van Huysduynen - LinkedIn
Alison Streaker - LinkedIn


The Science of Coffee is made possible by these leading coffee organisations

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

Roasting coffee can be maddening. Just 4° Celsius is enough to make the same green beans taste distinctly different! And there are so many things roasters can play around with: temperature, time, fan speed, drum speed, types of probes…the list goes on and on.

So, if you want to start roasting yourself, where do you start!?

In the first half of this episode, I interview one of the world's leading roasting teachers who takes me through his published scientific research to give a clear answer. It’s as simple as 80%, 15% and 5%.

And then, in the second half, I show you why roasting coffee consistently batch-after-batch is so difficult. But these problems are finally being solved with smart technologies.

I visited the ROEST engineering team in Oslo and cracked open their innovative prototype P3000 roaster to show you the technology that allows anybody to roast coffee consistently and fully automatically.

I am so impressed with these innovations, I believe they’re going to change the coffee industry.


Please spread the word about The Science of Coffee!

Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts
Leave a 5 star rating on Spotify


Dive deeper into the science of roasting

Explore ROEST’s innovative products for the coffee industry.
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


Connect with my very knowledgeable guests

Sverre Simonsen - LinkedIn
Callum Gilmour - LinkedIn
Veronica Balduc - LinkedIn
Morten Münchow - Coffee Mind website
Scott Rao - Instagram


The Science of Coffee is made possible by these leading coffee organisations

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories

Subscribe to A History of Coffee podcast

What flavours do you want from your coffee?

Every coffee bean begins its life green. And if you brewed it up without first roasting it, you’d get a yellow-green cup of grass-flavoured water.

But, as soon you apply heat to a bean, the flavour can morph to from something quite vegetative to a very acidic unripe fruit, then a very sweet fruit, and eventually dark roasted flavours.

This is the magic of coffee roasting!

In this episode of The Science of Coffee, I show you a full roast in action on the ROEST P3000, taste how coffee flavours evolve from acidic to bitter, and speak to leading coffee roasting scientists to reveal the mind-bending chemical and physical transformations taking place.

See for yourself Roest's innovative P3000 fully automatic roaster.


Please spread the word about The Science of Coffee!

Follow me on Instagram and tag me in an Instagram story
Write a review on Apple Podcasts
Leave a 5 star rating on Spotify


Connect with my very knowledgeable guests

Mark Al-Shemmeri - LinkedIn
Callum Gilmour - LinkedIn
Veronica Balduc - LinkedIn
Anja Rahn - LinkedInIldi Revi - LinkedIn
Samo Smrke - Instagram
Morten Münchow - Coffee Mind website


The Science of Coffee is made possible by these leading coffee organisations

BWT Water and More
Marco Beverage Systems
ROEST
Sustainable Harvest
Mahlkönig


The Science of Coffee is a spin-off series from James Harper's documentary podcast Filter Stories
Subscribe to A History of Coffee podcast