What is carbonic maceration in coffee processing?

Carbonic maceration is a technique borrowed directly from winemaking - specifically Beaujolais Nouveau production, where whole grape bunches ferment in a CO₂-rich environment. In coffee, whole cherries are placed in a sealed vessel flooded with carbon dioxide, displacing the oxygen.

What happens next is distinct from other fermentation methods. The absence of oxygen and presence of CO₂ triggers intracellular fermentation - enzymatic reactions occurring inside the intact cherry cells themselves rather than being driven by external microorganisms. The fermentation chemistry is different, typically producing wine-like, red fruit, or berry jam characteristics that conventional processing can't replicate.

The term is sometimes used interchangeably with anaerobic fermentation, but there's a meaningful distinction: carbonic maceration specifically means CO₂ injection and whole-cherry intracellular fermentation, which sets it apart even from standard sealed-tank anaerobic processing.