Origins and Introduction to Coffee
Carbonic maceration gained prominence in coffee when Saša Šestić won the 2015 World Barista Championship using a Sudan Rume variety processed with this technique . The term is borrowed from winemaking, where bunches of grapes are fermented in tanks with their stems, with carbon dioxide pumped directly into the tanks . Often described as giving fresh fruit flavors and lowering tannins, the technique is famously used to produce wines from the French region of Beaujolais and has been used in winemaking since 1934 .
Šestić had been working 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 coffee using carbonic maceration . 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 .
Process and Technical Implementation
In carbonic maceration, whole coffee cherries are sealed in airtight tanks, with carbon dioxide pumped in, which forces oxygen out. CO₂ creates pressure and pushes oxygen out, resulting in an anaerobic environment . The main differentiation from standard anaerobic fermentation is that the cherry is left intact and not pulped prior to entering a sealed tank, with the sealed vessel immediately pumped full of carbon dioxide .
During this process, whole coffee cherries are placed in sealed tanks where oxygen is displaced by carbon dioxide, creating an environment that promotes intracellular fermentation. This unique environment triggers enzymatic reactions within the coffee cherry that would never occur under normal aerobic conditions . The initial and most critical fermentation phase occurs inside intact cherries, with the core of CM being the enzymatic reactions and fermentation occurring within the cells of the intact cherry .
Because the skins of the cherries are left intact, fermentation may take days or weeks. The varying levels of pressure in the tank create different available sugars and pectins for the microbes to macerate. After five to seven days in a water-filled carbonic tank, the water becomes saturated with fermenting enzymes and byproducts . Unlike anaerobic fermentation, carbon maceration can take months to produce the right flavor of coffee because the cherries are left whole when they are placed in the barrels, rather than being pulped .
Flavor Profile and Sensory Characteristics
Carbonic maceration coffees often have “intense flavor profiles, with boozy and cooked fruit flavors” . 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 .
One of the hallmarks of CM coffees is their intense and often unique aromatics. These can range from bright red fruits and tropical notes to floral perfumes and even unexpected notes like cinnamon or bubblegum. The complexity can be stunning . Carbonic maceration coffees often have intense fruity notes, subtle wine-like aromas, pronounced sweetness, and a complex finish, often presenting a round, structured cup with elevated sweetness, a silky aftertaste, and vibrant fruit-forward notes .
According to Šestić, all the flavors and aromatics produced by carbonic maceration have no way to escape. Instead, they’re absorbed by the coffee parchment, contributing to a ‘stoned fruit’ quality in the cup . Recent anaerobic coffees have had incredibly precise and immediately identifiable flavor notes like gingerbread, cinnamon, licorice, bubble gum, or poached pear. The flavor tends to be singular, highly expressive and uncommon .
Infrastructure and Investment Requirements
Successfully implementing carbonic maceration requires significant investment in specialized equipment and infrastructure modifications. Coffee producers must carefully evaluate their facilities and budget for necessary upgrades before attempting this processing method. The technical requirements go far beyond traditional processing equipment, demanding precision instruments and controlled environment capabilities .
Processing coffees this way requires tanks that can be sealed, one-way valves to let the oxygen out and release pressure as CO₂ builds up. These tanks can be a big investment. Alongside adding an additional 60 hours to the coffee post-harvest process, carbonic maceration requires substantial investment in CO₂ tanks, and ideally, an on-site quality control lab for cupping and testing .
For complete infrastructures, the investment can be in the region of 1.34 million euros. Deploying these techniques represents a major investment. The installation of bioreactors and the use of specific cultures increase production costs by an average of 0.71 euros per kilogram compared with conventional methods . These experiments come with not only more risk, but more work, higher production costs, and require more equipment. This means that carbonic maceration and anaerobic coffees are usually more expensive than more traditional washed or natural and dry process coffees .
Challenges and Market Positioning
Carbonic maceration requires an intimate understanding of the variables involved and a view of the end goals. One of the most important necessities is the ability to cup. “It’s very difficult for producers to experiment, and to invest in specialized equipment if they can’t cup their experiments.” Many producers do have access to cupping labs, but many in the world do not .
The major barrier to the adoption of carbonic maceration is risk. The opportunity cost of experimenting can be devastating if the end product results in failure or is substantially below the buyer’s expectation. Then, of course, there is the financial investment in equipment that is required, which adds to the overall risk toll . Timing, financing, and limited facilities are all major factors that steer many coffee producers away from this processing method. While potentially offering a more controlled method of anaerobic fermentation in the long run, carbonic maceration is still quite experimental, and producers unfamiliar with the practice can find it quite risky. For these reasons, only select producers concentrated in South America are taking advantage of carbonic maceration .
Coffee professionals often describe carbonic maceration coffees as polarizing due to their unconventional flavor profiles. While some coffee lovers embrace these distinctive characteristics, others find them too unusual compared to traditional taste expectations. This processing method has sparked considerable debate within the specialty coffee community about flavor authenticity and processing innovation boundaries . Carbonic maceration is one of the top trends in the coffee industry at the moment. When it was introduced by Šestić in 2015, it became an overnight sensation. And while its impact on the characteristics of coffee is subjective, coffee businesses can set themselves apart by adding it to their line of offerings .
Future and Industry Impact
The future of carbonic maceration in coffee processing holds exciting possibilities for continued innovation and refinement. As more producers experiment with this method and equipment becomes more accessible, we can expect to see variations and improvements that address current limitations while expanding flavor possibilities. The intersection of technology, science, and coffee craftsmanship continues to evolve, creating new opportunities for creative expression and quality enhancement .
If a CO₂ environment allows the coffee to absorb its own sugars and aromas better, what’s to say it won’t absorb the flavors of other fruits also placed inside the tank? With four decades of experience on hand and multiple farms where he could experiment, Arcila was perfectly placed to bring this new idea to life. Arcila’s first experiments began in 2016, where he began with mandarin peels, placing them in the tanks along with the cherries for 48 hours before natural processing .
This can be achieved with “no risk” contracts, which agree to purchase the end product at a price that works for the producer, regardless of what the outcome of the experimentation is. This can be further supported by commitments to purchase greater quantities of beans at subsequent harvests. Ultimately, many producers, especially small and medium-sized players, need greater support from the supply chain when it comes to experimentation and innovation .