Unlocking the Funk: What Is Anaerobic Coffee Processing?

Unlocking the Funk: What Is Anaerobic Coffee Processing

In the world of specialty coffee, where origin, variety, and roast profile often steal the spotlight, there’s another game-changer quietly revolutionising what ends up in your cup: anaerobic processing. It’s wild, it’s weird, and it’s producing some of the most complex and expressive coffees on the planet.

So, what exactly is anaerobic coffee processing—and why should you care?

First, the Basics: What Is Coffee Processing?

Before coffee reaches your grinder, it has to be extracted from the fruit of the coffee cherry. This step—called processing—plays a crucial role in developing flavour. Traditionally, there are three main methods:

Washed (or wet): Clean, crisp flavours, acidity-forward.
Natural (or dry): Fruity, sweet, heavier-bodied.
Honey (or pulped natural): Somewhere in between, combining acidity and sweetness.

But then came the rebels. Enter anaerobic fermentation.

What Is Anaerobic Coffee Processing?

Anaerobic processing involves fermenting coffee beans in a sealed, oxygen-free environment—usually stainless steel or plastic tanks. By removing oxygen, farmers can manipulate microbial activity during fermentation, which alters how sugars and acids interact with the beans. This creates a completely different chemical and flavour development pathway compared to traditional open-air fermentations.

In short: it’s coffee science meets winemaking.

How Does It Work?

Here’s a simplified breakdown of the anaerobic process:

Harvest: Ripe coffee cherries are selectively picked by hand.
Tank Fermentation: The whole cherries (or depulped beans) are placed into airtight tanks. The absence of oxygen forces microbes to produce lactic acid, among other compounds.
Monitoring: Time, temperature, and pH are closely controlled. Some ferments last 12 hours; others stretch to 120+ hours.
Drying: After fermentation, the beans are dried—often on raised beds under the sun or in mechanical dryers.
Resting & Milling: Once dried, the parchment is removed and the green beans are rested before export.

Some producers go a step further, combining anaerobic fermentation with carbonic maceration (yes, from the wine world), adding layers of complexity and even funkier flavour profiles.

What Does Anaerobic Coffee Taste Like?

This is where things get exciting. Anaerobic coffees often produce intensely fruity, boozy, and sparkling profiles—the kind that jump out of the cup. Expect notes like:

Red wine
Tropical fruit
Bubblegum
Cinnamon
Cola
Floral or perfumed highs

They tend to have:

Bright acidity
Creamy or syrupy body
Long, evolving finishes

It’s not for everyone—and that’s part of the appeal. Anaerobic coffees are bold, experimental, and polarising. But when done well, they’re absolutely showstopping.

Why Are Coffee Farmers Embracing Anaerobic Processing?

Because it puts them in the driver’s seat. Anaerobic fermentation allows producers to:

Differentiate their coffee in a competitive market.
Add value to already high-quality cherries.
Express terroir in a new, controlled way.
Push boundaries of what coffee can be.

Countries like Costa Rica, Colombia, El Salvador, and Ethiopia are leading the way, with visionary producers designing custom fermentation protocols and sharing data to improve results harvest after harvest.

Are There Risks?

Yes—anaerobic processing is tricky. If fermentation isn’t carefully monitored, it can go south fast. Overfermentation can lead to:

Overly sour or vinegary flavours
Unwanted microbial growth
Mould or instability in the final cup

It requires precision, cleanliness, and know-how—which is why many anaerobic coffees carry premium prices. You’re not just paying for taste, but for the skill behind the scenes.

How to Brew Anaerobic Coffee

If you’ve picked up an anaerobic coffee, treat it like the unicorn it is. A few brewing tips:

Filter methods (like V60 or Kalita) often highlight the layers of fruit and acidity best.
Slightly cooler brew temps (91–93°C) can tone down volatile funk.
Let it rest! Anaerobic coffees often benefit from a longer post-roast rest—7 to 14 days—to fully mellow and open up.

Dialing in can take time, but the payoff is worth it.

Final Sips

Anaerobic coffee isn’t just a trend—it’s a sign of how far the coffee world has come in treating coffee as both an agricultural product and an artform. It offers a glimpse into the future of flavour: funky, fermented, and full of potential.

So next time you see “anaerobic” on a coffee label, take the plunge. You might just find your new favourite brew hiding in the tank.

Alex Kinder