Carbonic maceration is one of those terms that makes specialty coffee sound like it's borrowing from a sommelier's vocabulary. Which, as it happens, it is. This processing method was lifted almost directly from the wine world, and it's responsible for producing some of the most expressive, fruit-driven coffees you're likely to taste.
In simple terms, carbonic maceration involves fermenting whole, intact coffee cherries in a sealed tank that's been filled with carbon dioxide. The absence of oxygen triggers a specific kind of fermentation – happening inside the fruit itself – that coaxes out intense aromatics, vivid sweetness, and a clarity of flavour that sets it apart from other processing methods. It's one of the more controlled approaches available to producers, and when it's done well, the results can be extraordinary.
From Beaujolais to Barista Championships
Carbonic maceration didn't start with coffee. It's most famously associated with France's Beaujolais region, where it's been used for decades to produce light, fruit-forward red wines from the Gamay grape. The principle is straightforward: whole grape clusters are sealed in a CO2-rich tank, triggering fermentation inside the intact fruit before conventional yeast-driven fermentation takes over on the outside. The result is wine with lower tannins, bright fruit character, and immediate drinkability – think Beaujolais Nouveau.
The technique made the leap to coffee thanks to Saša Šestić, the Bosnian-Australian barista who won the 2015 World Barista Championship in Seattle. Šestić had been spending time with Australian winemaker Tim Kirk of Clonakilla, learning fermentation techniques and wondering whether the same principles could be applied to coffee. He collaborated with Colombian producer Camilo Merizalde at Finca Santuario to process a Sudan Rume variety using carbonic maceration – fermenting the cherries in stainless steel tanks with CO2, controlling temperature, and minimising oxygen exposure throughout.
The coffee he served at the WBC was striking: clean, complex, with a clarity of fruit character that judges hadn't encountered before. His win didn't just put carbonic maceration on the map – it sparked a broader industry conversation about what controlled fermentation could achieve. A decade on, the technique has moved well beyond competition stages and into commercial production around the world.
How does carbonic maceration work?
The process starts with cherry selection. Only ripe, intact fruit makes the cut – damaged or underripe cherries would allow external microorganisms in too early and undermine the whole point of the method.
The selected cherries are placed whole 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 the air inside the tank, creating a fully oxygen-free environment from the outset. This is one of the key differences between carbonic maceration and standard anaerobic fermentation, where oxygen is pushed out more gradually as the fermentation itself produces CO2.
With no oxygen present and the cherry skins still intact, there's limited contact between external yeasts and the sugars inside the fruit. Instead, enzymes within the cherry begin breaking down sugars and organic acids internally – a process called intracellular fermentation. This first phase is 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 the process, producers can monitor and adjust temperature, CO2 levels, pH, and fermentation duration. That level of control is what makes carbonic maceration so appealing – and so different from open-air fermentation, where the environment is at the mercy of weather, ambient temperature, and whatever microflora happen to be in the vicinity.
How is it different from washed, natural, and honey processing?
In a washed process, cherries are depulped and the mucilage removed before drying. It's the most common method in specialty coffee, and it tends to produce clean, bright cups with structured acidity and high clarity – the processing stays out of the way, letting terroir and variety speak.
Natural (or dry) processing goes the other direction. Whole cherries are dried intact, allowing the fruit to ferment slowly around the seed over days or weeks. This imparts more body and fruit character – berries, stone fruit, sometimes a winey quality – but with less consistency and a higher risk of things going sideways if conditions aren't carefully managed.
Honey processing sits between the two. The outer skin is removed but some or all of the mucilage is left on the seed during drying, producing cups that are typically sweeter and fuller-bodied than washed coffees, with more fruit character but less intensity than a full natural.
Carbonic maceration is a different proposition entirely. Because the fermentation happens inside sealed tanks in a CO2-rich environment – and because the cherry remains whole throughout the initial phase – the producer has a degree of control over flavour development that none of the above methods allow. The result is coffee that's often intensely fruity and aromatic, but with a structure and cleanliness that can feel almost paradoxical given how flavour-forward it is.
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 carbonic maceration coffee taste like?
Expect something expressive. These coffees tend to lead with juicy red fruit – cherry, raspberry, plum – alongside tropical notes like mango, lychee, and passionfruit. There's often a smooth, almost winey mouthfeel, with an acidity that's vibrant but well-integrated rather than sharp. The finish tends to be aromatic and lingering, with layers that reveal themselves as the cup cools.
Compared to standard anaerobic coffees, which can lean into heavier, more intense fruit or fermented characteristics, carbonic maceration often produces something brighter and more focused. The intracellular fermentation seems to emphasise clarity and sweetness over raw intensity. It's no coincidence that these coffees are a favourite 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 are worth approaching with a little extra care. The fermentation process can affect the bean's physical structure, often resulting in higher sugar content and greater heat sensitivity. Many roasters 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. Gentler heat application and careful monitoring through first crack tend to be the way to go – the flavour compounds you're trying to preserve are delicate, and they don't respond well to being rushed.
Try a carbonic maceration coffee
The best way to understand this process is to taste it. We stock carbonic maceration and anaerobic processed coffees when available – explore our current range.
And if you'd like to understand more about the broader family of oxygen-free fermentation methods – including how anaerobic processing works alongside washed, natural, and honey methods – head over to our deep dive on anaerobic fermentation.