The Science of Coffee

I travel to Colombia’s Huila region to answer a question that’s puzzled me for years: if specialty coffee pays more, is better for the environment, and brews tastier cups—why don’t more farmers grow it?

 

I speak with two producers in the same region whose choices couldn’t be more different. One stakes his future on specialty. The other opts out.

 

Their decisions come down to more than passion or a hard work ethic. Instead, I unco...

Volume. Cheap. Lame flavours. This is the traditional way of growing coffee in Brazil, and almost every farm does it this way. 

 

But what if you wanted to produce beautiful, distinctive flavours instead—and make a living from it?

 

In this episode, we travel to Fazenda Paraíso in Minas Gerais, Brazil, where farmer Vicente Pereira and his daughter are on a steep learning curve finding buyers for their beautiful coffees. 

 

Part 2 e...

Volume. Cheap. Lame flavours. This is the traditional way of growing coffee in Brazil, and almost every farm does it this way. 

 

But what if you wanted to produce beautiful, distinctive flavours instead—and make a living from it?

 

In this episode, we travel to Fazenda Paraíso in Minas Gerais, Brazil, where farmer Vicente Pereira and his daughter are on a steep learning curve finding buyers for their beautiful coffees. 

 

Part 1 u...

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 o...

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 p...

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 expl...

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 ...

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 ...

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 p...

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 we...

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 elab...

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 Sc...

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...

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 ...

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 th...

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 epis...

Ever wonder why you and your friends can taste the same coffee, but you can’t agree on the flavour notes? Join me as I explore this metaphysical mystery! I speak with leading scientists and ask: are the flavour receptors in your nose and mouth the same as mine? How does music and the shape of a cup affect what we taste? What about our different cultural backgrounds and language? Best of all, I put all these questions to the tes...

So you’ve just taken a sip of a very rare coffee, and flavours of passion fruit explode in your mouth. But here’s the thing: that flavour of passion fruit is not coming from your mouth. It’s not even coming from your nostrils. It’s being picked up behind your eyes! In this first episode of The Science of Coffee's second series, I unravel how our sense of smell and taste works to help you be a better coffee taster. I shrink us d...

We’re back with another series of The Science of Coffee! Across 10 science stories, narrative audio producer and coffee professional James Harper takes you on a journey into coffee's hidden microscopic secrets. James has spent the last year traveling to Central America, Greece, Norway, Switzerland and interviewing dozens of the world’s leading coffee scientists. This insights will help you appreciate coffee more deeply and make ...