What Is Anaerobic Coffee? Fermentation & Flavor Explained

If you've recently explored high-end specialty coffee, you've probably encountered words such as:

Anaerobic
Anaerobic Natural
Anaerobic Washed

You may also have seen tasting notes that sound unusually intense: passion fruit, strawberry candy, cinnamon, wine-like fruit, tropical flavours, florals, or fermented fruit.

But what is anaerobic coffee, exactly?

Is it a completely different coffee processing method?

Does it mean the coffee has been flavoured?

And why can anaerobic coffees taste so different from traditionally processed coffees?

Anaerobic coffee refers broadly to coffee that undergoes part of its fermentation under conditions where oxygen is strongly restricted.

By controlling the fermentation environment, producers can influence microbial activity and the compounds produced during processing—potentially creating distinctive sensory characteristics in the finished cup.

But there is an important detail:

Anaerobic fermentation is not necessarily a complete processing method by itself.

It can be combined with natural, washed, and other post-harvest approaches.

That's why you'll find terms such as Anaerobic Natural and Anaerobic Washed on specialty coffee bags.

At Speciality Coffee, you can explore these experimental processing styles directly:

Anaerobic Coffee

https://specialitycoffee.ca/collections/anaerobic

Anaerobic Natural Coffee

https://specialitycoffee.ca/collections/anaerobic-natural

Anaerobic Washed Coffee

https://specialitycoffee.ca/collections/anaerobic-washed

You can also browse our complete specialty coffee selection at:

https://specialitycoffee.ca/

And continue learning about coffee processing, origins, roasting, brewing, and specialty coffee through our All About Speciality Coffee Blog:

https://specialitycoffee.ca/blogs/all-about-specialty-coffee

What Does Anaerobic Mean in Coffee?

The word anaerobic refers to conditions where oxygen is absent or strongly limited.

In coffee processing, producers can place whole coffee cherries, depulped coffee, or coffee with varying amounts of mucilage into sealed fermentation vessels.

As microorganisms consume available oxygen and fermentation progresses, carbon dioxide and other compounds accumulate within the closed environment.

This creates different fermentation conditions from those found in an open vessel exposed to the surrounding atmosphere.

The result can be changes in:

• microbial activity;

• fermentation pathways;

• organic acids;

• volatile aromatic compounds;

• sensory characteristics.

However, anaerobic coffee processing isn't one standardized recipe.

Producers may use different:

• vessels;

• fermentation times;

• temperatures;

• pressures;

• coffee forms;

• microbial cultures;

• drying techniques;

• post-fermentation processing methods.

So when you read “anaerobic” on a coffee bag, it tells you something important about fermentation—but not everything about how that coffee was produced.

What Is Coffee Fermentation?

To understand anaerobic coffee, it helps to understand fermentation itself.

Coffee begins as a fruit.

After harvesting, microorganisms such as yeasts and bacteria interact with sugars and other compounds present in and around the coffee cherry.

Through fermentation, these microorganisms metabolize compounds and produce new substances, including organic acids and volatile compounds.

Fermentation can occur during many types of coffee processing.

It isn't unique to experimental coffee.

What changes with anaerobic fermentation is the environment in which that microbial activity takes place.

By limiting oxygen, producers change one of the variables that influences which microorganisms are active and what metabolic reactions occur.

That can influence the coffee's final sensory profile.

How Is Anaerobic Coffee Made?

There isn't one universal anaerobic coffee recipe.

However, a simplified process may look something like this:

1. Coffee Cherries Are Harvested

Ripe coffee cherries are picked and sorted.

Producers may remove unripe, damaged, or defective cherries before fermentation begins.

2. The Coffee Is Prepared for Fermentation

Depending on the intended process, the producer may ferment:

• whole cherries;

• depulped coffee;

• coffee with mucilage remaining;

• partially processed coffee.

This stage is crucial because anaerobic fermentation can be combined with multiple processing systems.

3. Coffee Is Placed in a Sealed Vessel

The coffee is transferred into a closed fermentation tank or another controlled vessel.

The system restricts the introduction of atmospheric oxygen.

As microorganisms consume remaining oxygen and generate CO₂, the environment inside the vessel changes.

4. Fermentation Is Monitored

Depending on the producer, variables may include:

• fermentation duration;

• temperature;

• pH;

• pressure;

• oxygen availability;

• microbial activity.

Some producers use relatively short fermentations.

Others intentionally extend fermentation to create different sensory outcomes.

5. The Coffee Continues Through Its Processing Method

After fermentation, the coffee might be:

• dried as a whole cherry;

• depulped and washed;

• dried with mucilage;

• subjected to another producer-specific processing stage.

This is where the difference between Anaerobic Natural and Anaerobic Washed becomes particularly important.

Is Anaerobic Coffee a Processing Method?

This is one of the most misunderstood questions.

It's usually more useful to think of anaerobic fermentation as a fermentation technique or fermentation environment that can form part of a broader processing method.

For example, you may encounter:

Anaerobic Natural

The coffee undergoes controlled fermentation under restricted-oxygen conditions and is then dried as a natural coffee, typically with the cherry remaining intact during drying.

Explore Anaerobic Natural Coffee:

https://specialitycoffee.ca/collections/anaerobic-natural

Anaerobic Washed

The coffee undergoes controlled fermentation and is subsequently processed using a washed approach, with fruit and mucilage removed before drying.

Explore Anaerobic Washed Coffee:

https://specialitycoffee.ca/collections/anaerobic-washed

This is why the word anaerobic alone doesn't tell you the entire processing story.

Two coffees labelled anaerobic can have dramatically different fermentation protocols, drying methods, varieties, origins, and flavour profiles.

Anaerobic Natural vs Anaerobic Washed

Understanding this distinction can make coffee shopping much easier.

Characteristic	Anaerobic Natural	Anaerobic Washed
Fermentation	Restricted-oxygen environment	Restricted-oxygen environment
Fruit during later processing	Typically remains around the seed during natural drying	Removed before final drying
Common sensory direction	Often intense fruit, sweetness and fermentation character	Often more clarity while retaining fermentation complexity
Body	Can be relatively full	Can feel cleaner or more structured
Fruit expression	Often ripe and highly expressive	Can be more defined and precise
Cup style	Can range from clean to highly funky	Can combine unusual fermentation notes with washed-coffee clarity

These are general tendencies, not rules.

An exceptionally controlled anaerobic natural can taste remarkably clean.

An anaerobic washed coffee can still be extremely expressive and unconventional.

Producer decisions matter enormously.

What Does Anaerobic Coffee Taste Like?

There is no universal anaerobic flavour.

This is one of the most important points to understand.

Anaerobic fermentation can produce very different results depending on:

• coffee variety;

• cherry ripeness;

• terroir;

• fermentation duration;

• fermentation temperature;

• oxygen conditions;

• microbial populations;

• processing method;

• drying;

• roasting.

However, some anaerobic coffees are known for unusually expressive sensory profiles.

You may encounter tasting notes reminiscent of:

• passion fruit;

• mango;

• pineapple;

• strawberry;

• raspberry;

• blueberry;

• tropical fruit;

• wine-like fruit;

• cinnamon;

• spices;

• florals;

• candy-like sweetness;

• fermented fruit.

Some coffees are vibrant and fruit-forward.

Others are floral and elegant.

Some are extremely clean.

Others intentionally push toward highly fermented, unconventional profiles.

If that sounds exciting, explore the complete Anaerobic Coffee Collection:

https://specialitycoffee.ca/collections/anaerobic

Why Can Anaerobic Coffee Taste So Intense?

Coffee fermentation is driven by microorganisms interacting with the chemical compounds surrounding the seed.

Changing oxygen availability changes the fermentation environment.

Research on self-induced anaerobic fermentation has shown that closed fermentation systems can produce different microbial activity and different concentrations of metabolites compared with conventional open fermentation.

Fermentation duration can also change the sensory outcome.

That means producers aren't simply leaving coffee in a tank and hoping for unusual flavours.

When carefully managed, fermentation becomes another tool for influencing how the coffee develops after harvest.

Still, more fermentation does not automatically mean better coffee.

Balance remains essential.

Is Anaerobic Coffee Flavored?

Not necessarily.

This distinction is extremely important.

A coffee can develop intense strawberry, mango, passion fruit, wine-like, or spice-like sensory notes without those ingredients ever being physically added.

Coffee naturally contains and develops a large range of aromatic compounds.

Fermentation can influence which compounds are created, transformed, retained, or emphasized.

So if an anaerobic coffee says:

Passion Fruit – Strawberry – Cinnamon

on the bag, those words may simply be tasting notes describing what trained tasters perceive.

They don't necessarily mean passion fruit, strawberry, or cinnamon was added during processing.

Anaerobic Coffee vs Co-Fermented Coffee

These terms should not automatically be treated as synonyms.

In a traditional anaerobic fermentation, the coffee itself is fermented under oxygen-restricted conditions without necessarily adding flavouring ingredients.

A co-fermentation, by contrast, can involve introducing additional biological materials or ingredients into the fermentation environment depending on the producer's method.

Because terminology across experimental coffee processing isn't completely standardized, you should look carefully at the producer's description.

If a coffee was fermented with fruit, spices, or another added ingredient, responsible product information should ideally make that clear.

This distinction matters because a naturally developed fermentation profile is different from a coffee whose processing deliberately included additional ingredients.

Is Anaerobic Coffee Naturally Fruity?

It can be.

But anaerobic fermentation doesn't automatically create tropical fruit flavours.

The original coffee already matters enormously.

A high-quality coffee begins with variables such as:

• variety;

• terroir;

• climate;

• altitude;

• cherry ripeness;

• agricultural practices.

Fermentation then interacts with that raw material.

A producer can't turn every coffee into an exceptional anaerobic simply by placing it inside a sealed tank.

Great processing begins with great coffee and careful control.

Why Is Anaerobic Coffee So Popular in Specialty Coffee?

Specialty coffee has increasingly focused on discovering and expressing flavour diversity.

For decades, important variables included:

• origin;

• farm;

• producer;

• altitude;

• variety;

• processing method;

• roast profile.

Experimental fermentation adds another dimension.

Instead of fermentation being treated only as a necessary step in removing fruit or preparing coffee for drying, producers can manage it as a variable capable of influencing sensory expression.

This has produced coffees with flavour profiles that many coffee drinkers find surprising.

Some can feel almost completely different from traditional expectations of what coffee should taste like.

That's part of their appeal.

Why Are Producers Experimenting With Fermentation?

Coffee producers operate in a competitive global market.

Exceptional quality and differentiation can create additional value for distinctive lots.

Fermentation gives producers another variable they can work with alongside:

• genetics;

• agriculture;

• cherry selection;

• processing;

• drying;

• storage.

When well controlled, experimental fermentation may help create distinctive sensory profiles.

However, experimental processing also requires expertise.

Variables such as temperature, fermentation time, microbial activity, oxygen, pH, cherry quality, and drying conditions can all influence the result.

This is why the producer remains one of the most important people behind an exceptional coffee.

Does Longer Anaerobic Fermentation Mean Better Coffee?

No.

Longer isn't automatically better.

Research has shown that fermentation duration can change microbial metabolism and sensory profiles, but the relationship between time and quality is not simply:

longer fermentation = better coffee.

If fermentation becomes poorly controlled, undesirable sensory characteristics can develop.

The ideal conditions depend on the coffee and the producer's objectives.

A skilled producer may choose a fermentation duration designed to enhance the coffee without overwhelming its original character.

What Does “Funky Coffee” Mean?

In specialty coffee, funky is an informal sensory term often used to describe unusual or intense fermentation-related flavours.

A funky coffee may remind someone of:

• fermented fruit;

• wine;

• tropical candy;

• unusual spices;

• very ripe fruit;

• liqueur-like aromatics.

Some coffee drinkers absolutely love these profiles.

Others prefer much cleaner and more traditional coffee.

Neither preference is wrong.

Anaerobic fermentation can produce both ends of this spectrum.

Some coffees are intensely funky.

Others are remarkably elegant.

Can Anaerobic Coffee Be Clean?

Absolutely.

“Anaerobic” doesn't automatically mean wild or heavily fermented.

Carefully managed fermentation can produce coffees with:

• high clarity;

• distinctive fruit;

• florals;

• elegant acidity;

• structured sweetness;

• clean aftertaste.

This is especially important when comparing Anaerobic Natural and Anaerobic Washed coffees.

If you're curious about a profile that combines experimental fermentation with potentially greater clarity, explore:

https://specialitycoffee.ca/collections/anaerobic-washed

What Is Anaerobic Natural Coffee?

Anaerobic natural coffee combines an oxygen-restricted fermentation stage with natural-style drying.

The coffee commonly undergoes fermentation as whole cherries before the cherries continue through natural processing and drying.

This combination can produce especially expressive sensory profiles.

Common tasting directions may include:

• tropical fruit;

• berries;

• ripe fruit;

• candy-like sweetness;

• florals;

• fermentation complexity;

• fuller body.

Again, there are no guarantees.

Producer technique determines the result.

Explore current Anaerobic Natural Coffees:

https://specialitycoffee.ca/collections/anaerobic-natural

What Is Anaerobic Washed Coffee?

Anaerobic washed coffee combines oxygen-restricted fermentation with a washed processing approach.

Depending on the exact protocol, coffee may undergo fermentation at different stages before the fruit and mucilage are removed and the seeds are dried.

This can create an interesting sensory balance.

You may experience some of the intense or unusual characteristics associated with controlled fermentation while maintaining the clarity often associated with washed coffee.

Potential characteristics may include:

• defined fruit;

• floral complexity;

• structured acidity;

• pronounced sweetness;

• fermentation-derived aromatics;

• clean finish.

Explore our Anaerobic Washed Collection:

https://specialitycoffee.ca/collections/anaerobic-washed

Anaerobic Coffee vs Natural Coffee

Natural coffee refers primarily to a broader processing method in which the coffee dries inside the whole cherry.

Anaerobic refers primarily to the fermentation environment.

That's why a coffee can be both anaerobic and natural.

A traditional natural coffee may ferment and dry under more open environmental conditions.

An anaerobic natural introduces a controlled low-oxygen fermentation stage before or as part of the natural process.

The sensory result may be very different.

If you enjoy fruit-forward natural coffees but want something potentially more experimental, Anaerobic Natural can be an exciting next step:

https://specialitycoffee.ca/collections/anaerobic-natural

Anaerobic Coffee vs Washed Coffee

The same principle applies.

A conventional washed coffee and an anaerobic washed coffee can both eventually follow washed-processing principles.

The difference is that anaerobic washed coffee incorporates fermentation under oxygen-restricted conditions.

Traditional washed coffees are often associated with:

• clarity;

• florals;

• citrus;

• structured acidity;

• precise origin character.

Anaerobic washed coffees can retain some of that clarity while introducing additional fermentation complexity.

Explore:

https://specialitycoffee.ca/collections/anaerobic-washed

Is Anaerobic Coffee Better Than Washed or Natural Coffee?

No processing method is automatically superior.

Anaerobic coffee isn't inherently better because it sounds more technical or experimental.

A beautifully produced traditional washed Ethiopian coffee may be more impressive than a poorly executed anaerobic coffee.

An exceptional natural coffee may offer more complexity than an average experimental fermentation.

Quality depends on the complete chain:

• coffee genetics;

• farming;

• harvest;

• cherry selection;

• processing;

• fermentation;

• drying;

• storage;

• roasting;

• brewing.

Experimental processing should serve the coffee—not become a substitute for quality.

Does Anaerobic Processing Hide Terroir?

This is an important debate within specialty coffee.

Some coffee professionals value highly expressive experimental fermentations because they create distinctive and exciting sensory experiences.

Others prefer processing approaches that place greater emphasis on the coffee's variety and terroir.

Both perspectives have merit.

Very strong fermentation characteristics can sometimes become one of the most dominant parts of a coffee's sensory profile.

That doesn't automatically make the coffee bad.

It simply changes what the drinker experiences.

Some coffees prioritize transparency.

Others prioritize fermentation-driven expression.

Specialty coffee can accommodate both.

Which Brewing Method Is Best for Anaerobic Coffee?

There's no single correct brewing method.

Anaerobic coffees can work well with:

• V60;

• Kalita Wave;

• flat-bottom drippers;

• AeroPress;

• batch brew;

• espresso.

Your choice depends on the coffee and what you want to emphasize.

Anaerobic Coffee for Pour-Over

Pour-over brewing can be especially interesting for complex anaerobic coffees because it allows you to explore aromatic detail and flavour separation.

A high-quality anaerobic coffee might reveal different characteristics as the cup cools.

You may initially notice florals.

Then tropical fruit.

Then spice.

Then deeper sweetness.

This evolution through temperature is one of the reasons experimental coffees can be fascinating to taste slowly.

Anaerobic Coffee for Espresso

Anaerobic coffees can also produce highly distinctive espresso.

A fruit-forward anaerobic espresso might deliver extremely concentrated aromatics and sweetness.

Depending on the coffee, you might experience impressions reminiscent of:

• tropical fruit;

• berries;

• candy;

• spice;

• wine-like fruit;

• florals.

However, very light or highly experimental coffees may require careful dialing in.

Grind size, ratio, temperature, and extraction time can dramatically influence whether the coffee tastes balanced.

Who Should Try Anaerobic Coffee?

Anaerobic coffee is particularly interesting for adventurous coffee drinkers.

If tasting notes such as:

passion fruit, mango, strawberry, tropical candy, berries, wine-like fruit, florals, or cinnamon

sound exciting, you may enjoy exploring anaerobic coffees.

Start here:

https://specialitycoffee.ca/collections/anaerobic

If you already enjoy natural coffees and want something potentially more expressive:

https://specialitycoffee.ca/collections/anaerobic-natural

If you prefer clarity but still want to explore experimental fermentation:

https://specialitycoffee.ca/collections/anaerobic-washed

Who Might Prefer Traditional Processing?

Not everyone wants intensely experimental coffee.

If you prefer:

• subtle flavours;

• extremely high clarity;

• delicate florals;

• classic origin expression;

• restrained fermentation;

you may prefer traditionally processed washed coffees.

That doesn't mean you should avoid anaerobic coffee entirely.

You could begin with a clean anaerobic washed coffee before moving into more intense anaerobic naturals.

Think of experimental coffee as a spectrum rather than a category where every coffee tastes the same.

How to Taste Anaerobic Coffee

When trying anaerobic coffee for the first time, don't focus only on the tasting notes printed on the bag.

Brew the coffee and observe it carefully.

Pay attention to:

• aroma;

• sweetness;

• acidity;

• fruit intensity;

• fermentation character;

• florals;

• body;

• aftertaste;

• flavour changes as the cup cools.

Some experimental coffees change dramatically with temperature.

A characteristic you barely notice while the coffee is hot may become extremely obvious once the cup cools.

This makes slower tasting particularly rewarding.

How to Compare Anaerobic Coffee

One of the best ways to understand anaerobic fermentation is through comparison.

Try tasting:

Traditional Natural vs Anaerobic Natural

or:

Traditional Washed vs Anaerobic Washed

Ideally, compare coffees from a similar origin or producer.

Use the same brewing method and similar brewing parameters.

Then look for differences in:

• fruit intensity;

• acidity;

• sweetness;

• fermentation character;

• flavour clarity;

• aroma;

• aftertaste.

That is when the term anaerobic stops being marketing language and starts becoming something you can recognize through sensory experience.

Explore Anaerobic Specialty Coffee in Canada

Experimental fermentation represents one of the most fascinating areas of modern specialty coffee.

It gives producers another set of tools for exploring flavour while giving coffee drinkers access to sensory profiles that can be dramatically different from traditional coffee.

At Speciality Coffee, you can explore multiple anaerobic processing styles from respected specialty coffee roasters.

Browse all Anaerobic Coffees:

https://specialitycoffee.ca/collections/anaerobic

Explore Anaerobic Natural Coffees:

https://specialitycoffee.ca/collections/anaerobic-natural

Discover Anaerobic Washed Coffees:

https://specialitycoffee.ca/collections/anaerobic-washed

Browse our complete specialty coffee selection:

https://specialitycoffee.ca/

And continue exploring coffee processing, brewing, roasting, origins, and specialty coffee culture through our All About Speciality Coffee Blog:

https://specialitycoffee.ca/blogs/all-about-specialty-coffee

Frequently Asked Questions 

What is anaerobic coffee?

Anaerobic coffee is coffee that undergoes part of its fermentation under conditions where oxygen is strongly restricted. Producers commonly create these conditions using sealed fermentation vessels, allowing them to influence microbial activity and fermentation development.

Does anaerobic coffee mean no oxygen at all?

The term is commonly used in specialty coffee to describe oxygen-restricted fermentation. Exact oxygen conditions vary depending on the equipment and protocol, so not every coffee labelled “anaerobic” necessarily follows identical fermentation conditions.

Is anaerobic coffee a processing method?

It's generally more accurate to describe anaerobic fermentation as a fermentation technique or environment that can be incorporated into different processing systems. That's why coffees can be labelled Anaerobic Natural or Anaerobic Washed.

What does anaerobic coffee taste like?

There isn't one universal flavour. Anaerobic coffees can display intense fruit, berries, tropical characteristics, spices, florals, wine-like aromas, candy-like sweetness, or fermentation-derived complexity. Some are extremely clean, while others are intentionally funky.

Is anaerobic coffee flavored?

Not necessarily. Powerful fruit and spice-like tasting notes can develop through the coffee itself and its fermentation without flavourings being added. However, some co-fermentation techniques intentionally introduce additional ingredients, so reading the producer's processing information is important.

What is anaerobic natural coffee?

Anaerobic natural coffee combines an oxygen-restricted fermentation stage with natural processing, where the coffee is subsequently dried with the cherry intact.

Explore:

https://specialitycoffee.ca/collections/anaerobic-natural

What is anaerobic washed coffee?

Anaerobic washed coffee combines controlled oxygen-restricted fermentation with a washed processing approach in which the fruit and mucilage are removed before final drying.

Explore:

https://specialitycoffee.ca/collections/anaerobic-washed

Is anaerobic coffee better?

Not automatically. Experimental fermentation can create extraordinary sensory complexity, but processing alone doesn't determine coffee quality. Green coffee quality, producer expertise, fermentation control, drying, roasting, and brewing all matter.

The Bottom Line: What Is Anaerobic Coffee?

So, what is anaerobic coffee?

In simple terms, it is coffee that undergoes part of its fermentation under strongly restricted-oxygen conditions.

By changing the fermentation environment, producers can influence microbial activity and potentially create new sensory expressions.

But anaerobic isn't one flavour and it isn't one complete processing method.

You can have:

Anaerobic Natural

https://specialitycoffee.ca/collections/anaerobic-natural

Anaerobic Washed

https://specialitycoffee.ca/collections/anaerobic-washed

And many other producer-specific variations.

Some anaerobic coffees are intensely fruity and funky.

Others are clean, floral, and elegant.

Some emphasize fermentation.

Others maintain impressive origin clarity.

The best experimental processing doesn't exist simply to make coffee taste unusual.

The objective should still be the same as with every great specialty coffee:

create an exceptional cup.

Ready to explore experimental coffee?

Browse the complete Anaerobic Coffee Collection:

https://specialitycoffee.ca/collections/anaerobic

Discover Anaerobic Natural:

https://specialitycoffee.ca/collections/anaerobic-natural

Explore Anaerobic Washed:

https://specialitycoffee.ca/collections/anaerobic-washed

Browse all specialty coffee:

https://specialitycoffee.ca/

And continue learning through the All About Speciality Coffee Blog:

https://specialitycoffee.ca/blogs/all-about-specialty-coffee