Anaerobic Fermentation: The Oxygen-Free Flavour Trip

So you've been hearing the word "anaerobic" tossed around in coffee circles and maybe even spotted it on a bag at our roasterie. It sounds like something out of biology class, but it’s showing up more and more in specialty coffee. So—what is it, really? And why are so many people into it?

If you’re still getting your footing with fermentation in general, pause here and check out our intro guide: 👉 Fermented Coffee 101. That’ll give you the background you need. This post? We’re going deep on anaerobic fermentation specifically. Let’s unpack it—with no lab coat required.

First of All: What Even Is Anaerobic?

The word “anaerobic” literally means without oxygen. So, as you’d expect, this type of fermentation happens in a sealed environment. Think airtight tanks, often with valves that let gas escape but don’t let fresh air in. Once the coffee cherries (or pulped beans) are locked in, microbes go to work doing their thing—without oxygen interfering.

That’s a big shift from more traditional fermentation, where the beans are left to soak or rest in open-air tanks or piles. Anaerobic slows things down. It creates more control, more consistency, and lets producers dial in some pretty wild flavour outcomes.

So Why Are Roasters and Drinkers So Obsessed?

Because it changes the rules. Cutting off oxygen affects the kinds of microbes that thrive, which affects how sugars and acids break down, which totally shifts what ends up in your cup.

The result? Coffees that taste:

  • Juicy and tropical (pineapple, mango, guava)
  • Winey or boozy (but in a “this reminds me of sangria” way, not “this sat in the sun too long”)
  • Creamy and smooth (we’re talking texture here—almost velvety)
  • Unexpected (weird in a good way, like a new favourite song you didn’t know you needed)

It’s Not Just for Show-Offs

Look, we get it. Sometimes words like "anaerobic" get thrown around like coffee buzzword bingo. But this isn't just trend-chasing. When it’s done right, anaerobic fermentation isn’t just a science experiment—it’s a creative tool. One that lets producers highlight parts of a coffee’s flavour that would stay hidden otherwise.

It also takes a bit of guts. Anaerobic fermentation is trickier to control than traditional methods. The tanks need to be watched, temperatures need to be stable, and the cherries need to be perfectly ripe. Mess it up, and the whole lot can go sideways.

So if a producer pulls it off? That’s skill. That’s intention. And you’ll taste the difference.

Got Anything Anaerobic I Can Actually Drink?

Yes. Yes, we do.

Right now on the shelf, we’ve got our Yirgacheffe Aramo, and it’s a killer example of how nuanced anaerobic coffee can be. This one’s from Ethiopia, and it leans into everything we love about this process—without going overboard.

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Eithiopia Yirgachefe - Aramo

$26.00 CAD
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Expect cocoa nibs, grapefruit zest, bright acidity, and sweet spice. It’s juicy, clean, and interesting without being loud. More "wow, that’s layered" than "whoa, what is this?!"

It doesn’t mean every anaerobic coffee is wild. Some are mellow and elegant. Some taste like fruit punch. It depends on the coffee and the producer. But you’ll almost always get something new—and that’s part of the fun.

So, Is Anaerobic for You?

If you’re into trying new things and paying attention to what’s in your cup, then yeah—it probably is. Anaerobic fermentation offers something you won’t get from washed or natural coffees. Not better, not worse. Just... different.

And if you're not there yet? That’s cool too. We’ve got plenty of clean, approachable coffees that still bring the flavour without needing a chemistry breakdown.

The point is: there’s no one way to coffee. But if you’re feeling adventurous, this is one of the most exciting paths to wander down.

Stay in the Loop

Right now, Aramo is your go-to anaerobic at the Roasterie. But you know how we roll—things change fast around here.

We’ve got new coffees arriving all the time, and 2025 just so happens to be our 40th anniversary. That means a year-long parade of:

  • New releases (including more anaerobics)
  • Flash sales
  • Subscriber-only discounts
  • Giveaways

And whatever other surprises we feel like throwing your way