Anaerobic and Experimental Coffees: What the Labels Mean
Why Coffee Got Experimental
For most of coffee’s history, there were three ways to process it: washed, natural or honey . In the last decade, producers have borrowed ideas from winemaking and brewing to control fermentation, the work yeast and bacteria do on the coffee fruit’s sugars. The results can taste nothing like “coffee flavor”: tropical fruit, cinnamon, rum, bubblegum.
These lots are often expensive and always divisive. This guide explains the terms so you know what you are buying.
Anaerobic Fermentation
Fermentation without oxygen. Instead of fermenting in open tanks or drying in open air, the coffee (whole cherries or pulped beans) is sealed in airtight tanks or bags, sometimes for several days. Different microbes thrive without oxygen, and they make different flavor compounds.
- Tastes: intense, winey, boozy or tropical; sometimes yogurt-like or cinnamon.
- Label might say: “anaerobic natural”, “anaerobic washed”, “72-hour anaerobic”.
Carbonic Maceration
A winemaking technique, applied to coffee. Whole cherries go into sealed tanks flushed with carbon dioxide (CO₂), and they ferment from the inside out before being pulped or dried. It is a specific kind of anaerobic fermentation.
It became famous in 2015, when Australian barista Saša Šestić won the World Barista Championship with a carbonic-macerated Colombian coffee.
- Tastes: very fruity but often clearer and cleaner than other anaerobic coffees; red wine, grape, cherry.
Yeast Inoculation
Adding a chosen yeast. Just as brewers pick a beer yeast, some producers add a specific yeast or bacteria culture to the fermentation tank to steer the flavor and make it more predictable. Often described as “inoculated” or by the yeast’s name.
Co-Fermented and Infused Coffees
This is where opinions split.
- Co-fermented: coffee fermented together with fruit (mango, passion fruit, peach), spices (cinnamon) or other ingredients.
- Infused: flavor added to the coffee from another source, such as fruit, juice or flavorings.
Supporters see it as creativity, like fruited beers. Critics say it hides the coffee’s real character and can mislead buyers. In 2024 the Best of Panama competition disqualified four coffees it judged to be infused. The World Barista Championship takes the opposite view: since late 2023 its rules allow infused and co-fermented coffees, as long as the ingredients are added before the green-coffee stage.
There is currently no specific labeling rule for these coffees, so it is largely up to roasters to disclose them.
Tip: If a coffee’s tasting notes read like a candy store (“strawberry milkshake, cinnamon roll”) and the bag says “co-fermented” or names fruit in the process line, expect added ingredients. If that matters to you, ask the roaster.
Other Terms You May See
| Term | What it means |
|---|---|
| Thermal shock | Beans soaked in hot and then cold water after fermentation; producers claim it helps lock in aroma |
| Double fermentation | Two fermentation stages, e.g. in cherry and then after pulping |
| Extended fermentation | A longer-than-usual washed or natural fermentation |
| Lactic process | Fermentation steered toward lactic acid bacteria; tastes creamy, yogurt-like |
Should You Buy One?
| You might love it if… | You might skip it if… |
|---|---|
| You enjoy natural wines, sour beers or fruit-forward naturals | You want to taste a farm’s origin and variety clearly |
| You want a “wow, that’s coffee?” moment | You drink coffee with milk (the subtle notes get lost) |
| You are happy to pay extra for something unusual | You prefer predictable, everyday coffee |
Try one as a pour-over or AeroPress, black, a little cooler than usual so the flavors open up. Buy a small bag the first time: experimental coffees are expensive, and you will know within a cup whether they are for you.