TASTING: Blackcurrant, Valencia orange, dried cherry & grape candy. Roasted for espresso.
What Is Carbonic Maceration?
Carbonic Maceration is the process of fermenting coffee beans in barrels to enrich flavour and aromatics. Well its a little more complex than that.
Borrowed from the production of wine, carbonic maceration is a fermentation technique that first came to prominence in the coffee industry in 2015. Looking to create a coffee with more aromatic complexity and a low concentration of acetic acid, barista champion Saša Šestić introduced carbonic maceration when he used it for a Barista Championship-winning coffee.
Alongside his collaborator, Colombian farmer Camilo Merizalde, Šestić developed the technique after learning about its use in wine. In wine, carbonic maceration uses the injection of carbon dioxide (CO2) to ferment the grapes without breaking the skins, so that the process happens inside each grape individually. The initial fermentation is not caused by yeast, but instead occurs intracellularly, or from the inside out.
In coffee, it involves placing harvested coffee cherries in airtight barrels before pumping in CO2 to create a CO2-rich environment. The CO2 allows the cherries to break down different levels of pectins, often producing bright and winey coffees with strong notes of red fruits.
According to Šestić, all the flavours 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. During the process, they use low temperatures to avoid alcohol build-up.
Once the coffee has reached its desired level of fermentation, the cherries can be processed by either washing or drying. (Both processing methods are suitable for carbonic macerated coffee.
Unlike anaerobic fermentation, carbon maceration can take months to produce the right flavour coffee. This because the cherries are left whole when they are placed in the barrels, rather than being pulped.
