Sipping on Science with Coffee Fermentation
Sipping on Science — 6 Coffee Fermentation Methods Explained
Smooth, fruity, rich, bitter, buttery, spicy — every sip of coffee speaks a different taste story. Recently, fermented coffee has been gaining popularity as producers experiment with controlled fermentation to unlock exotic flavours and distinctive notes.
While every coffee bean undergoes some fermentation during processing, fermented coffees take it further — making fermentation the star of the show rather than a behind-the-scenes step. Learn more about how coffee processing and fermentation shape flavour.
1. Anaerobic Fermentation
Coffee cherries are sealed airtight in plastic bags or special metal tanks designed to release gases without allowing oxygen in. The cherries ferment for 12 to 100 hours depending on the producer's experience. No gases are pumped in — it's left alone in a low-oxygen environment.
Flavour result: Bright, crisp, and clean with traditional flavour notes.
2. Carbonic Maceration
Borrowed from the wine industry, this method places whole coffee cherries (unpulped) into airtight stainless steel barrels where carbon dioxide is injected to facilitate the breakdown of pectin within the cherries.
Flavour result: Bright, winey coffee with strong red fruit notes.
Coffeeza Salawara Single-Estate follows this process — an experimental approach that pushes the boundaries of flavour potential.
3. Fruit Fermentation
Wet-processed or semi-washed beans are pulped, then slices or mashed fruit are added alongside the coffee beans for fermentation. After fermentation, the seeds are dried and sent to the roastery.
Flavour result: Enhanced natural sweetness and body with a delicious fruity essence.
Coffeeza Baarbara Single-Estate uses a pineapple fermentation process — coffee beans fermented with pineapple slices for a uniquely tropical flavour profile. Other producers experiment with grapes, oranges, wine yeast, and passionfruit.
4. Koji Fermentation
Rooted in ancient Japanese technique (traditionally used for soy sauce, miso, and sake), koji fermentation uses spores of a filamentous fungus to enhance the complexity and body of coffee. Cherries undergo a 3-day initial fermentation, then are treated with fungus spores for an additional 60 hours.
Flavour result: Notes ranging from chocolate and gingerbread to tropical fruits like pineapple and mango — with a buttery, full-bodied mouthfeel.
5. Double Fermentation
Common in East Africa, this method ferments and washes coffee twice. Beans are placed in water-filled canals for fermentation, washed, then fermented and washed again before drying.
Flavour result: Incredibly clear cup with bright, crisp fruit flavours.
6. Barrel-Aged Coffee
Unroasted green coffee is placed inside barrels that previously housed whiskey, gin, rum, or wine. The beans absorb subtle notes and nuances from the prior contents, developing uniquely complex new flavours. Coffee producers are now forming partnerships with distilleries to perfect this method.
Flavour result: Boozy, complex, and deeply aromatic — unlike any other coffee.
Beyond These Six
Countless other fermentation methods are being created and experimented with every day — including yeast fermentation (using wine yeast) and nitro fermentation (using nitrogen instead of carbon dioxide). The world of specialty coffee fermentation is only just beginning.
Try Coffeeza's Fermented Single-Estate Coffees
Experience these innovative fermentation methods for yourself with Coffeeza Salawara (carbonic maceration) and Coffeeza Baarbara (pineapple fruit fermentation). Explore our full coffee capsule range and join the Coffeeza Gold Club Membership to earn rewards on every order.
