The Science of Coffee

2) Coffee Extraction

The Science of Coffee

Show Notes

How you brew your coffee dramatically affects what you taste. And I do mean dramatic! Brewing up the same bag of coffee beans can taste like a slice of heaven, or a slap in the face.

So, what exactly is happening at a microscopic level when water swirls through coffee grinds? Why does boiling water extract certain flavours, while letting the kettle cool for five minutes make it taste markedly different?

In this episode, we dive deep into the academic research conducted at the UC Davis Coffee Center so you can choose your flavour adventure: Do you like your coffees when they’re a sour bomb? A floral caress on the lips? A smokey drag on a pipe? Or a treacle of sweet syrup?

We also explore why it can be so difficult getting the same flavours from the same beans consistently. And finally, I equip you with tools so you can begin finding your perfect brew.

—---

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

Explore this episode’s sponsor Marco Beverage Systems SP 9 brewer and how it delivers consistent brews in the cafe (https://link.filterstories.org/3Tgh18r)

Listen to the Adventures in Coffee episode about making dramatically different brews using the Aeropress: https://link.filterstories.org/3TghsQ7

Want more to listen to more documentary podcasts about coffee? Check out Filter Stories - https://link.filterstories.org/3zb5vnO

Want to go deeper into coffee extraction?

Mackenzie Batali’s fractionation research - https://link.filterstories.org/3CFnvH0

UC Davis’ brewing control chart research - https://link.filterstories.org/3CLoiGz

Take courses on coffee brewing with the Specialty Coffee Association - https://link.filterstories.org/3EQFoVV

Study at the UC Davis Coffee - https://link.filterstories.org/3TwSgod

Read ‘The Craft and Science of Coffee’ - https://link.filterstories.org/3zb7bN8

Connect with my very knowledgeable guests:

Samo Smrke - LinkedIn (https://link.filterstories.org/3EKrjtg) and Instagram (https://link.filterstories.org/3IdrfRz)

Bill Ristenpart - Academic profile (https://faculty.engineering.ucdavis.edu/ristenpart/)

Mackenzie Batali - LinkedIn (https://link.filterstories.org/3s7VRxr)

Peter Giuliano - LinkedIn (https://link.filterstories.org/3yT66tv)

Danny Pang - LinkedIn (https://link.filterstories.org/3Sd9mqq)

David Walsh - LinkedIn (https://link.filterstories.org/3VEH7Uo)

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

BWT Water and More

Marco Beverage Systems

Trabocca

Eversys

Oatly

Fiorenzato

Subscribe to A History of Coffee podcast: https://link.filterstories.org/2NArChO Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

What kind of racing car does the Gaggia Classic GT home espresso machine remind you of? Use discount code FS202610 to get 10% off.

More from The Science of Coffee

Dec 8, 2025

For twenty years, the 2004 cupping form profoundly shaped the specialty coffee world. But on the hillsides of coffee farms, some of the form’s byproducts have been disadvantaging producers. In this episode, we follow two producers whose lives collided with the myth of universal quality. These stories reveal how a single idea of “quality” can close doors for the people with the least power in the supply chain. The new coffee evaluation form, the CVA, is still young, and with any luck it will keep evolving. I hope for a form that can empower even the smallest producers. Please support my work directly at Ko-fi.com/FilterStories Other ways you can help: Leave a 5 star rating on Spotify Follow me on Instagram and tag me in an Instagram story Write a review on Apple Podcasts Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter Go deeper into the story of quality: The original Filter Stories episode about Murray Cooper in Ecuador, Firefly Specialty Coffee Association's new Coffee Value Assessment 2004 cupping form from the Specialty Coffee Association of America SCAA Coffee Cuppers Handbook (4th edition, 2011) Kenneth Liberman's book, "Tasting Coffee: An Inquiry into Objectivity" SCA's video series on the CVA presented by Peter Giuliano Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

Dec 8, 2025

If you ask two specialty professionals what makes a high-quality coffee, you’ll likely get a surprisingly consistent answer: clean, sweet, juicy, bright. To an outsider, they would be forgiven for thinking coffee quality is universally defined. But the truth is more sober. In this episode, we examine how a simple cupping form helped create a universal idea of quality. We then look at the evidence that, in fact, it’s just the personal preferences of a small group of people masquerading as universal quality. Please support my work directly at Ko-fi.com/FilterStories Other ways you can help: Leave a 5 star rating on Spotify Follow me on Instagram and tag me in an Instagram story Write a review on Apple Podcasts Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter Go deeper into the story of quality: 2004 cupping form from the Specialty Coffee Association of America SCAA Coffee Cuppers Handbook (4th edition, 2011) Cup of Excellence cupping form Kenneth Liberman's book, "Tasting Coffee: An Inquiry into Objectivity" SCA's video series on the CVA presented by Peter Giuliano Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

Dec 8, 2025

For the longest time, coffees were dull and bitter. But then a small group of pioneers changed the world. In this episode, we travel back to the 1960s and ’70s to meet the trailblazers who realised coffees could taste distinctive: sweeter, brighter, cleaner. We discover how their personal preferences became a movement, then a form, and eventually a global definition of “quality”. Please support my work directly at Ko-fi.com/FilterStories Other ways you can help: Leave a 5 star rating on Spotify Follow me on Instagram and tag me in an Instagram story Write a review on Apple Podcasts Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter Go deeper into the story of quality: Specialty Coffee Association's new Coffee Value Assessment 2004 cupping form from the Specialty Coffee Association of America SCAA Coffee Cuppers Handbook (4th edition, 2011) Michael Sheridan of CQI discussing the inter-organisational politics behind the Houston Expo announcement on Lee Safar's Map It Forward podcast Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

Jul 28, 2025

For the longest time, the coffee community only cared about water’s impact ruining espresso machine boilers and kettles. But what about water’s impact on coffee flavour? In this episode, I tell the story of how the specialty coffee community came to understand water chemistry: the pioneering work of the computational chemist Christopher Hendon and British roaster Maxwell Colonna-Dashwood, the genesis of the SCA’s Water Quality Handbook, and where we are today understanding the impact of minerals on our water. I strongly recommend listening to the two episodes before this one first: Getting great water for coffee, step-by-step & The two ingredients in water that ruin your coffee, and the ancient story behind them 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 Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter Want to go deeper into water chemistry? Read the SCA’s Water Quality Handbook BWT White Paper on the effects of magnesium (German) Christopher Hendon’s Instagram where he’ll announce his new version of his book, Water for Coffee Do an online Certificate of Advanced Studies at the Coffee Excellence Centre Season 3 of The Science of Coffee is made possible by these leading coffee organisations: The Coffee Quest | BWT | TODDY | Algrano | Probat Note: this is a reworked version of my 2022 episode Water for Brewing Coffee, including portions of my 2024 episode How to think like a scientist, part 2. Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

Jul 28, 2025

550 million years ago, earth was perfect. We had perfect water for coffee AND we were living in a vegetarian paradise! But then Earth changed—violently. The planet shifted from a peaceful, plant-eating paradise to a darker, more brutal world. And in this new world, the chemistry of water was forever altered. This is the wild story of how earth-shaking forces and the spirits of long-dead critters ruin your coffees today. This story will help you remember the two invisible ingredients in your water that have a huge impact on coffee flavour and your brewing equipment: calcium and hydrogen carbonate. Read Marcia Bjonerud’s amazing book, Reading the Rocks 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 Discover how I make these Filter Stories episodes by subscribing to my Substack newsletter Season 3 of The Science of Coffee is made possible by these leading coffee organisations: The Coffee Quest | BWT | TODDY | Algrano | Probat Note: this is a reworked version of my 2022 episode Water for Brewing Coffee. Use ProfilePrint to find the coffee your customers loved last year (without a week of cupping!). Use promo code "FILTER" to get 10% off your first year of a Mini Beluga subscription. Click here to discover ProfilePrint's many uses.

See all episodes →