What is fourth wave coffee?

Fourth wave coffee extends the third wave from roughly 2015 onward by layering science, data and technology on top of it: controlled fermentations (anaerobic, co-ferments), AI-assisted roasting, sensor-driven extraction, blockchain traceability and more individual profiles. Where the third wave revealed terroir, the fourth wave puts it on the lab bench.

The 'fourth wave' label is not a registered trademark or an official standard like SCA specialty coffee. It is an editorial shorthand that began circulating in the English-speaking coffee press from around 2015-2017 to mark a shift: where the third wave had centred on origin and roasting, the fourth wave reaches upstream into post-harvest processing and downstream into measured extraction. A symbolic turning point is Australian barista Sasa Sestic's victory at the 2015 World Barista Championship in Seattle, where he used a Panamanian Sudan Rume from Boquete processed with carbonic maceration — a technique borrowed from Beaujolais wine. That moment popularised so-called 'innovative' fermentations: anaerobic washed and natural, co-ferments with fruits or selected yeasts, thermal shock, lactic process, kombucha process.

The fourth wave is also a technology wave. On the roasting side, platforms like Bellwether Coffee (an electric roaster with cloud-controlled profiles) and Decent Espresso (an open-source espresso machine with real-time pressure, flow and temperature sensors) embody the philosophy: extract, measure, adjust, share. On the traceability side, blockchain projects such as Farmer Connect — a consortium launched in 2020 with IBM and several industry players — let the drinker scan a QR code and trace the cup back to the cooperative, sometimes to the individual farmer. NFT experiments around microlots appeared between 2021 and 2023, without yet becoming mainstream.

Lastly, the fourth wave is the wave of espresso without a traditional machine: manual presses like Flair and Cafelat Robot, compact stove-heated units like 9Barista, and the AeroPress (invented in 2005), which has become a global experimentation platform through the World AeroPress Championship. In Europe, the Belgian scene — Brussels, Ghent, Antwerp, Liège — gradually integrates these tools, often in specialty-oriented wine bars that treat morning coffee as another vertical of their drink list, notably around La Hulpe and Genval.

Markers of fourth wave coffee