CO2 Fermentation Boosts Natural-Process Coffee Scores in Colombian Trial

"In the best-performing treatment, a 24-hour CO2 "modified atmosphere" fermentation, the coffee averaged an 86.90 final score, compared with 82.15 for an unfermented control."

"Despite advances in coffee fermentation research, most studies have been conducted under laboratory-controlled or wet fermentation conditions, limiting their applicability to natural (dry) processing systems. There is still scarce empirical evidence on how modified-atmosphere fermentation, particularly with CO2, affects the chemical and sensory quality of dry-processed coffees under real production settings."

"The authors of this study said it links a simple modified-atmosphere setup to measurable gains in SCA scores for natural-process coffee, while also tying parts of the chemical profile - sugars and fatty acids - to sensory outcomes under real production conditions on a working farm."

Colombian researchers tested five fermentation approaches for whole coffee cherries using the Specialty Coffee Association's 100-point cupping protocol. A 24-hour CO2 modified-atmosphere fermentation produced the highest scores at 86.90 points, significantly outperforming unfermented control samples at 82.15 points. The study, published in December 2025, addresses a gap in coffee fermentation research by examining dry-processed coffees under real production conditions rather than laboratory settings. The findings link modified-atmosphere fermentation with improved chemical profiles, including increased sugars and fatty acids, while demonstrating measurable sensory improvements. This research provides a framework for more repeatable and scalable strategies in specialty coffee production, particularly for small-scale producers experimenting with natural processing techniques.

Read at Daily Coffee News by Roast Magazine