Carbonic maceration is one of those terms that makes coffee sound like it's wandered in from a wine bar. Which, to be fair, it has. Borrowed straight from winemaking, this processing method is behind some of the most vivid, fruit-packed coffees you'll come across.
At its core, carbonic maceration is about fermenting whole, intact coffee cherries in a sealed tank that's been flushed with carbon dioxide. That low-oxygen setup nudges the fruit into a different kind of fermentation – one that happens inside the cherry itself. The result is a coffee with striking clarity, layered sweetness, and flavours that feel dialled up rather than muddled.
From Beaujolais to baristas
Carbonic maceration didn't start in coffee. It's been used for decades in France's Beaujolais region to make bright, fruit-forward red wines from Gamay grapes. Whole bunches go into a sealed tank, CO2 fills the space, and fermentation begins inside the grapes before yeast gets involved on the outside. The result is wine that's soft, juicy, and ready to drink early – Beaujolais Nouveau being the best-known example.
The jump to coffee came via Saša Šestić, the Bosnian-Australian barista who won the 2015 World Barista Championship in Seattle. After spending time with Australian winemaker Tim Kirk of Clonakilla, Šestić collaborated with Colombian producer Camilo Merizalde at Finca Santuario to try the same approach with a Sudan Rume variety – sealed tanks, CO2, temperature control, the works.
The coffee he served stood out immediately. Clean but punchy. Fruit-forward but precise. His win played a major role in bringing carbonic maceration into mainstream specialty conversation, and in a broader shift in how producers think about fermentation – not just as a step, but as a tool.
A decade on, carbonic maceration has moved well beyond competition coffee and into commercial production around the world.
So, what's actually going on?
It starts with cherry selection. Only ripe, intact fruit makes the cut. Damaged or underripe cherries would let external microorganisms in too early and undermine the whole point of the method.
Those selected cherries go into a sealed tank – typically stainless steel – which is then flushed with carbon dioxide from an external source. Because CO2 is heavier than oxygen, it physically displaces much of the air, creating a largely oxygen-free environment from the outset.
This is one of the key differences between carbonic maceration and standard anaerobic fermentation. Most producers doing anaerobic fermentation start by immersing cherries in water and rely on native yeasts and bacteria to consume the initial oxygen before anaerobic metabolism takes over. In carbonic maceration, the oxygen-free environment is created chemically at the start; in most anaerobic fermentation, it's created microbiologically as the process unfolds.
It's worth saying that complete sterility isn't really achievable in either case – it's a question of dominance rather than total exclusion. But the CO2 flush gives carbonic maceration producers an earlier, more stable starting point.
With little oxygen present and the cherry skins still intact, external microbes have limited access to the sugars inside the fruit. Instead, the fruit cells themselves begin to switch to anaerobic metabolism – breaking down sugars internally and producing ethanol, glycerol, and a range of aromatic compounds. This is intracellular fermentation, and it's where much of the distinctive flavour development happens. It continues until the cherry skins eventually break down, at which point conventional microbial fermentation takes over on the outside.
Throughout, producers can monitor and adjust temperature, CO2 levels, pH, and fermentation duration. That level of control is what sets carbonic maceration apart from open-air fermentation, where the environment is at the mercy of weather, ambient temperature, and whatever microflora happen to be in the vicinity.
There's also a related technique worth knowing about, often called anoxic fermentation – where producers take the CO2-flush approach further by pitching a specific lab-cultivated yeast culture into the tank. It shares the starting premise with carbonic maceration (remove oxygen chemically rather than microbiologically) but takes the control question in a different direction, selecting the microbes that do the fermenting rather than leaving it to the cherry's own enzymes. Our deep dive on anaerobic fermentation covers this in more detail.
How does it compare to other processing methods?
Washed coffees are all about clarity. The fruit is removed early, leaving the bean to show clean acidity and structure – processing stays out of the way, letting terroir and variety speak.
Natural coffees go the other way. The whole cherry dries around the seed over days or weeks, building body and fruitiness – sometimes beautifully, sometimes unpredictably, depending on how carefully conditions are managed.
Honey processing sits in the middle. Some mucilage is left on the seed during drying, adding sweetness and texture without going full natural.
Carbonic maceration plays a different game. It's not just about what's left on the bean during drying, but how the fruit behaves before it's removed. The sealed, controlled environment allows producers to shape flavour in a much more deliberate way than any of the above methods allow.
It's worth noting that carbonic maceration is a fermentation step, not a complete processing method on its own. Once the tank fermentation is finished, the coffee still needs to be dried – and that drying stage can follow washed, honey, or natural principles, each combination producing a different outcome in the cup.
What does it taste like?
In a word: expressive.
Expect red fruits like cherry, raspberry, and plum, often backed by tropical notes – mango, lychee, passionfruit. There's usually a rounded, almost silky mouthfeel, with acidity that's bright but well behaved. The finish tends to be aromatic and lingering, with layers that reveal themselves as the cup cools.
A lot of that character comes from esters – aromatic compounds formed when alcohols produced during fermentation interact with organic acids in the fruit. Esters are responsible for many of the lifted, fruit-forward notes we associate with this style of processing, and the extended intracellular fermentation phase tends to produce them in abundance.
Compared to some anaerobic coffees, which can lean heavier or more intensely fermented, carbonic maceration often feels more focused. Still bold, but cleaner around the edges. It's no coincidence these coffees show up in barista competitions – they reward careful brewing, and filter methods like V60 or Chemex tend to let the aromatics shine.
A note for home roasters
If you roast your own coffee, carbonic maceration lots benefit from a lighter touch. The fermentation process can affect the bean's physical structure, often resulting in higher sugar content and greater heat sensitivity.
You'll often find a delayed first crack compared to conventionally processed coffees from the same origin, and the window between development and scorching can be narrower than you'd expect. Slower heat application and careful monitoring through first crack tend to pay off – the flavour compounds you're trying to preserve are delicate, and they don't respond well to being rushed.
Give it a try
The easiest way to get your head around carbonic maceration is to taste it. We stock coffees processed this way when available, alongside other fermentation-led lots – have a look at what's on right now.
If you'd like to go deeper on the broader family of oxygen-free fermentation methods, our deep dive on anaerobic fermentation is a good next step. Same family, different personality.