What is Carbonic Maceration Coffee?
Carbonic Maceration creates a unique and distinctive flavour profile, which here shines in harmony with the other characteristics of the beans. That’s without a doubt down to the fantastic quality of careful post-harvest processing, which we’ve seen in all the family’s coffees over many years now.
So, what is Carbonic Maceration?
Well, it means putting the freshly picked cherries into a sealed tank which is rich in Carbon Dioxide. This makes it a particular type of Anaerobic Fermentation. Because the fruit skin is intact, there's not a lot of contact between yeast (on the outside of the fruit) and any sugars that could ferment. Instead, the enzymes inside the fruit begin to break down sugars as well as other compounds, releasing Carbon Dioxide and Alcohol whilst this happens.
This is a method adapted from the wine world, and there's research there about how this changes flavours by the compounds which are released - it's often described as giving fresh, fruity flavours of cherry and red fruit, which fits well with our experience of the process in coffees too. This method is most famously used on grapes in the French winemaking region of Beaujolais and occasionally in Rioja in Spain.
How is it Different from Washed or Honey Processing?
| Process | Description | Common Flavour Profiles |
|---|---|---|
| Washed | Cherries are depulped and fermented in water to remove mucilage. | Clean, bright, with high acidity and clarity. |
| Honey (Pulped Natural) | Some mucilage is left on the bean during drying. | Sweet, syrupy, with more body and fruitiness. |
| Carbonic Maceration | Whole cherries ferment in a CO₂-rich, sealed tank. | Complex, winey, fruity, often with tropical or red fruit notes. |
Unlike washed or honey processes, carbonic maceration allows greater control over fermentation variables - such as temperature, time, and microbial activity - enabling producers to “guide” the flavour development with precision.
What Happens to the Beans?
- CO₂ is flushed into the tank, displacing oxygen and creating an anaerobic environment.
- Internal enzymatic activity begins breaking down sugars and acids inside the cherry.
- Microbial fermentation occurs more slowly and in a more controlled way than in open-air methods.
- The beans absorb more sugars and acids from the surrounding fruit, leading to intensified and layered flavour profiles.
This method can also alter the bean’s physical structure, making it more heat-sensitive during roasting. Roasters often report:
- Delayed first crack
- Higher sugar content, which can lead to scorching if not carefully managed
- More oily surface appearance, even at lighter roast levels
What Can You Expect Flavour-Wise?
- Juicy and vibrant, often with notes of red fruits, cherry, tropicals, or even bubblegum
- Silky or winey in mouthfeel
- Complex in acidity, with a lingering, aromatic finish
These coffees are often described as expressive and experimental, making them a favourite in competitions and among adventurous drinkers.
Carbonic Maceration Beyond Coffee: Origins in Winemaking
Carbonic maceration didn’t start with coffee - it was first developed in the wine industry, where it’s still widely used today to produce light, fruity, and low-tannin red wines, particularly in Beaujolais, France.
How It Works in Wine:
- Whole grape clusters are placed in a sealed tank filled with CO₂, just like in coffee.
- Intracellular fermentation begins inside the intact grapes, converting sugars and malic acid into alcohol and aromatic compounds without yeast intervention at first.
- Once the alcohol level reaches around 2%, the grape skins burst, releasing juice that then undergoes traditional yeast fermentation.
This process results in wines that are:
- Bright and fruit-forward, often with notes of banana, bubblegum, strawberry, and cinnamon
- Low in tannins and acidity, making them easy-drinking and approachable
- Often described as “glou-glou” wines - meant to be enjoyed young and fresh
Applications and Innovations:
- Beaujolais Nouveau is the most famous example, but the technique is now used globally in wines made from Gamay, Pinot Noir, Syrah, and even white varieties.
- Winemakers also use semi-carbonic maceration, where only part of the fermentation is anaerobic, to balance structure and fruitiness.
- In Australia, a patented version uses dry ice and sealed plastic bags to create the CO₂-rich environment.
Why It Matters for Coffee:
The adoption of carbonic maceration in coffee borrows directly from this winemaking tradition. The controlled fermentation environment, emphasis on internal enzymatic activity, and focus on flavour modulation are all inspired by decades of experimentation in wine. It’s a brilliant example of cross-industry innovation, where techniques from one craft elevate another.