You open a bag of coffee, and the smell hits you immediately.
Blueberry. Tropical fruit. Maybe something funkier—like fermented funk, not bad funk.
You brew it, and the flavour is intense. Bold. Weird. Nothing like the coffee you normally drink.
What happened? You bought anaerobic processed coffee.
And you're either going to love it or hate it. There's no middle ground.
Here's what anaerobic processing actually is, why farmers are doing it, and whether it's worth buying.
What's Actually Happening: The Simple Version
Regular coffee processing: Pick cherry, remove fruit, dry the bean. Simple.
Anaerobic processing: Pick cherry, seal it in an airtight container or tank, let it ferment in a controlled oxygen-free environment, then remove the fruit and dry it.
That's it. The difference is: one lets air in, one keeps air out.
Why this matters: When there's no oxygen, different microbes take over. Different fermentation happens. Different flavours develop.
The Pain Point: Your Normal Coffee Tastes Boring (Or Anaerobic Tastes Weird)
Let's be honest about what's happening here.
If you usually drink regular processed coffee:
Anaerobic tastes funky. Fruity in a way that doesn't feel "normal" for coffee. Blueberry? Tropical fruit? Fermented notes? It can feel weird if you're not expecting it.
Your first thought might be: "Is this coffee bad? Should it taste like this?"
The answer: No, it's not bad. Yes, it should taste like this. Your brain just isn't used to it.
If you've been curious about different coffee flavours:
Anaerobic opens up a whole new world. Suddenly, coffee tastes like fruit, not just "brown and bitter." It's exciting. It's different. It's worth exploring.
Why Farmers Do Anaerobic Processing (And It's Not Just For Fun)
Farmers aren't doing anaerobic processing to make coffee taste weird. They're doing it for practical reasons—and the flavour is a happy accident.
Reason 1: Control The Fermentation
Regular processing: Fermentation happens in the open air. It's chaotic. Microbes vary. Results vary. One batch might taste amazing, the next batch tastes average.
Anaerobic processing: Seal it up, control the environment, control the fermentation, get consistent results. Every batch tastes similar.
Why it matters: Farmers can predict and replicate flavours. Consistency = higher prices. Higher prices = better income for farmers.
Reason 2: Expand The Flavour Window
Regular processing: You've got certain flavour notes you can hit—fruity, chocolatey, balanced.
Anaerobic processing: You can go way further. Fermented, tropical, funky, wild. Flavours you can't get any other way.
Why it matters: Specialty coffee buyers (like roasters) want unique flavours. Unique flavours = higher prices. Farmers who master anaerobic processing make more money.
Reason 3: Save Water (In Dry Regions)
Regular washed processing: You need water. Lots of it. Washing the cherry, fermenting in tanks, cleaning equipment—water everywhere.
Anaerobic processing: You seal everything in a tank. No water needed for fermentation. The cherry's own juices do the work.
Why it matters: In regions where water is scarce, anaerobic processing lets farmers produce specialty coffee without depleting water supplies.
It's practical. It's sustainable. The weird fruit flavours are just what happens when you ferment coffee without oxygen.
Anaerobic Fermentation
What It Actually Tastes Like (And Why)
Okay, so you've got a bag of anaerobic processed coffee. What are you in for?
The Flavour Range
Mild anaerobic (short ferment, 24-48 hours):
- Subtle fruity notes (berry, citrus)
- Still recognisable as coffee
- Smooth mouthfeel
- Good entry point if you're nervous
Medium anaerobic (3-5 day ferment):
- Bold fruit flavours (blueberry, tropical)
- Fermented notes starting to show
- Juicy body
- Definitely different, but not shocking
Wild anaerobic (5+ day ferment):
- Intense fermented funk
- Tropical and exotic fruit
- Wine-like qualities
- Tastes nothing like regular coffee
- Love it or hate it territory
Why It Tastes This Way
What's happening in the tank:
- You seal the cherry (with or without the fruit) in an airtight container
- Naturally occurring microbes start eating the fruit and bean
- Without oxygen, different microbes dominate (anaerobic bacteria and yeast)
- These microbes produce different flavour compounds than regular fermentation
- You get wild fruit and fermented flavours you can't get any other way
The science bit (simple version):
Oxygen-free fermentation produces volatile compounds that taste fruity, floral, and funky. These compounds don't develop in regular, open-air fermentation.
Different fermentation times = different flavour intensities.
Short ferment = subtle fruit
Long ferment = wild funk
The Honest Truth: You Might Not Like It
Let's be real.
Anaerobic processed coffee is not for everyone. If you've been drinking regular coffee your whole life and you like it balanced and smooth, anaerobic might taste "wrong" to you.
Signs anaerobic might not be for you:
✗ You prefer subtle, balanced flavours
✗ You like your coffee to taste like coffee (not fruit)
✗ Funkiness/fermented notes sound gross to you
✗ You think coffee should taste chocolatey and smooth
Signs anaerobic might be perfect for you:
✓ You like bold, experimental flavours
✓ You're curious about different coffee profiles
✓ You like fruit-forward coffee
✓ You're bored with regular coffee flavours
✓ You don't mind "weird"
Anaerobic Fermentation
The Comparison: Anaerobic vs Regular Processing
Here's the side-by-side so you understand the difference:
| Regular Processing | Anaerobic Processing |
|---|---|
| Open-air fermentation | Sealed, oxygen-free fermentation |
| 12-72 hours ferment | 24 hours to 2+ weeks ferment |
| Predictable flavours | Unpredictable, wild flavours |
| Chocolate, nutty, balanced | Fruit, fermented, funky |
| Tastes like "coffee" | Tastes like fruit, wine, funkiness |
| Consistent batch to batch | Each batch is unique |
| Lower price | Higher price (specialty) |
| Great entry point | Adventurous coffee lovers |
Should You Try It? (The Real Answer)
Yes, but with expectations set.
If you're curious: Buy a small amount (250g bag, not 1kg) from a roaster you trust. Brew it. Taste it without judgment. See if you like it.
If you hate it: Don't blame the coffee. Anaerobic just isn't for you. That's fine. Stick with regular processing.
If you love it: Welcome to the weird, fruity, fermented side of coffee. You're in for a flavour journey.
Pro tips:
- Start with a mild-to-medium anaerobic (not the wildest one they've got)
- Brew it as filter or pour-over (highlights the fruit flavours)
- Don't expect it to taste like regular coffee (it won't, and that's the point)
- Check the roast date (anaerobic flavours fade faster than regular coffee)
Some producers wrap coffee during the cool night to retain heat, protect it from rain, and continue the fermentation process.
Why Some Roasters (Including Us) Get Excited About It
From a roaster's perspective, anaerobic processing is interesting because:
It's challenging: Every batch is different. You have to taste carefully and roast accordingly.
It's rewarding: When you nail the roast on anaerobic beans, the flavours are stunning. Fruit pops. Fermentation shines.
It's sustainable: Farmers in water-scarce regions can produce specialty coffee without destroying water supplies.
It's different: In a market full of regular coffees, anaerobic stands out. Coffee lovers notice.
It tells a story: Every anaerobic batch is unique. You can trace it back to a specific farmer, a specific ferment time, a specific flavour goal.
The Bottom Line: Anaerobic Is An Adventure
Anaerobic processing is what happens when you seal coffee cherries in a tank and let science do weird, wonderful things.
The result? Intense fruit flavours, fermented notes, and a coffee that tastes nothing like regular coffee.
You'll either:
- Think it's the most exciting coffee you've ever tasted
- Think it's too funky and weird
- Be somewhere in between
There's no wrong answer. Coffee is subjective. Your taste buds are your guide.
Want To Try Anaerobic?
We occasionally source anaerobic processed coffees when we find ones worth getting excited about.
They're usually single-origin, specialty-grade, from farmers pushing the boundaries of what coffee can taste like.
Browse our current coffees to see if we have any anaerobic lots available right now.
If we do, grab a small bag. Brew it. See what you think.
If you love it, you've discovered something new.
If you hate it, at least you tried something adventurous.
Either way, your coffee journey just got more interesting.
No bad coffee. No bad days.