Experimental Coffee Processing: Anaerobic, Carbonic Maceration & More
Experimental coffee processing means changing how coffee cherries are fermented and dried after harvest to create new flavors, beyond the traditional washed, natural and honey methods. The most common experiments are anaerobic fermentation (fermenting without oxygen), carbonic maceration (fermenting whole cherries in carbon dioxide), and co-fermentation (fermenting with added fruit, yeast or other ingredients). These coffees often taste intensely fruity, boozy or candy-like, and they tend to be divisive.
If you're new to processing, start with the three traditional methods in our introduction to coffee processing methods.
Photo: Cafe Imports
Experimental Processing Methods at a Glance
| Method | How it works | Typical flavors |
|---|---|---|
| Anaerobic fermentation | Cherries or beans ferment in sealed tanks with no oxygen | Intense fruit, tropical, sometimes boozy or spicy |
| Carbonic maceration | Whole cherries ferment in tanks filled with carbon dioxide, a technique borrowed from winemaking | Juicy red fruit, wine-like, very sweet |
| Extended fermentation | Cherries ferment much longer than usual before drying | Ripe fruit, fermented, winey |
| Yeast inoculation | Specific yeast strains are added to control fermentation | Cleaner, more predictable fruit and sweetness |
| Co-fermentation | Coffee ferments with added fruit, spices or other ingredients | Very pronounced flavors, like cinnamon, strawberry or tropical fruit |
| Thermal shock | Beans are soaked in hot, then cold water after fermentation to lock in aromatics | Bright, aromatic, very fruity |
How Experimental Processing Differs From Traditional Methods
Traditional processing comes in three main styles. Washed coffees have the fruit removed before drying, for clean, bright flavors. Natural coffees dry whole inside the cherry, for jammy, fruity flavors. Honey coffees have the skin removed but some sticky fruit left on, landing in between. Experimental methods add controlled steps, like sealed tanks, set temperatures, timed fermentations or added yeast, that push flavors in specific directions.
Why Producers Experiment
- Higher prices. Distinctive, high-scoring coffees can sell for much more, which helps small farms stand out.
- More control. Sealed tanks and measured fermentations can make results more consistent than open-air fermentation.
- New flavors. Experiments let producers show off what their varieties and farms can do.
The Debate Over Experimental Coffees
Experimental coffees can be stunning, but not everyone loves them. Some drinkers find the flavors too intense or boozy, and critics argue that heavy processing, especially co-fermentation with added ingredients, can hide the coffee's own character. There's also an ongoing conversation about labeling: many in the industry want co-fermented coffees clearly labeled so buyers know when flavors come from added ingredients rather than the coffee itself. Done well, experimental processing is a real craft. Just know what you're buying.
How to Brew Experimental Coffees
- Pour over is the best place to start. It keeps the cup clear so the unusual flavors stand out. Try our pour over recipe.
- Go a little coarser or cooler if it tastes harsh. Very fruity, fermented coffees can taste sharp when over-extracted. Try 195 to 200°F water.
- Try it iced. Fruity experimental coffees make excellent flash brew.
- Taste as it cools. Fruit and floral notes often come forward as the cup drops from hot to warm.
Try Something Different
Want to explore beyond blends? Our seasonal single origins rotate as new crops arrive, and natural process coffees like our Ethiopia Natural Guji show how much processing shapes flavor. Roaster's Choice brings you a different coffee every two weeks, picked by our roasters. Learn to describe what you taste with our guide to coffee tasting notes.
Quick Answers
What is experimental coffee processing?
New ways of fermenting and drying coffee after harvest, like anaerobic fermentation or carbonic maceration, used to create distinctive flavors.
What is anaerobic coffee?
Coffee fermented in sealed tanks without oxygen. It usually tastes intensely fruity and sometimes boozy or spicy.
What is carbonic maceration coffee?
Coffee made by fermenting whole cherries in tanks filled with carbon dioxide, a method borrowed from winemaking. It often tastes juicy, sweet and wine-like.
What is co-fermented coffee?
Coffee fermented with added ingredients like fruit, spices or yeast. The added ingredients strongly shape the flavor, so it should be labeled clearly.
Is experimental coffee better?
Not necessarily. It's different. Some people love the bold, fruity flavors, while others prefer classic washed or natural coffees.
How should I brew anaerobic coffee?
Pour over is a great start. If it tastes sharp, grind a little coarser or use slightly cooler water, around 195 to 200°F.
