Charcoal-bed espresso: the story behind Milan 2021

People still ask me about the charcoal.

In October 2021, on the WBC stage in Milan, I served espresso to four sensory judges by pouring it from a small carafe over a bed of activated charcoal, into the cup. It was the moment a lot of people first met me. Some thought it was theatre. A few thought it was witchcraft. The truth is much simpler and much better.

What we were trying to deliver

The routine used a blend of Kenyan Batian and Ruiru 11 from Maguta Estate in Kirinyaga. Both are disease-resistant cultivars that have spent twenty years being dismissed as "yield coffees" by buyers who never actually tasted them well-grown.

The story I wanted the judges to taste was: these cultivars are the future of Kenyan farming, and they cup as well as the SL28 you all remember from 2009.

To get there in nine minutes, every flavour note in the espresso needed to land cleanly. No mud. No fight with milk fat. No clash with the porcelain.

Why charcoal

Activated charcoal does three things to a flavour signal:

1. It adsorbs volatile compounds. It grabs aromatics and holds them for a beat before releasing them.
2. It scrubs astringency. Tannins and bitter alkaloids bind to its surface area.
3. It is, mechanically, an enormous surface area. A teaspoon of activated coconut charcoal has the internal surface area of a small football pitch.

What this means in practice: if you pour a hot espresso slowly through a thin bed of charcoal, you give the cup a tiny extra polish. The astringent tail rounds. The aromatics arrive in a softer order. You're not changing what's there. You're letting what's there read more cleanly.

We tested it for months. We tested with cellulose, with bone char, with paper, with nothing. The activated coconut charcoal won every blind tasting. So that's what went on stage.

What it wasn't

It wasn't an attempt to filter out a defect. The coffee was clean to begin with.

It wasn't a coating or a topping. The charcoal stayed in the carafe pan; nobody drank charcoal.

It wasn't symbolic. It was a tool. The Kenyan story was symbolic.

What the judges said

After the round, one of the head judges came over and said something I've thought about ever since. She said, "I have never tasted Batian like that. I had no idea."

That is the line I'm working for, for the rest of my career. Not the score. The line.

What I learned from it

A few things I tell every barista I coach now, taken straight from that round:

• Build the signal first, then the story. The judges drink before they listen. If the cup doesn't deliver, no narrative saves it.
• Test every variable blind. I was sure cellulose would win. It didn't. Trust the cupping, not your taste-memory of the cupping.
• Use new techniques only when they earn their place. Theatre for theatre's sake is the fastest way to lose a sensory panel that has tasted everything.
• Tell an origin story that respects the origin. I am Kenyan. The coffee was Kenyan. The story was Kenyan. The technique served all of that.

The charcoal got the headlines. The Batian got the work. Martin