Preliminary Data on Monitoring the Fermentation of Liberica Coffee using a Sensor-Integrated Mini Bioreactor

Fermentation in bioreactor systems can enhance coffee quality, standardize microbial activity, and improve the reproducibility of specialty coffee production. This study evaluated the performance of a custom mini-bioreactor with real-time gas sensors for monitoring the fermentation of Coffea liberica cherries inoculated with Bacillus cereus. The system continuously measured CO₂, H₂, CH₄, ethanol, temperature, and pH, enabling a comprehensive profiling of fermentation. Sensory evaluation and LC-MS chemical fingerprinting assessed the impact of microbial fermentation on coffee quality. Fermentation with B. cereus (FCB) produced higher levels of CO₂ (545 ppm), H₂ (379.11 ppm), ethanol (472.32 ppm), and CH₄ (1.85 ppm) than fermentations with Leuconostoc(FBL) and Exiguobacterium indicum (FBE), except for CH₄. LC-MS analysis confirmed that fermentation preserved the core chemical profile of Liberica coffee, with caffeine as the dominant compound. These results show that sensor-integrated bioreactor systems offer a scalable, controllable platform for real-time monitoring and optimization of coffee fermentation. Key words: Bacillus cereus; coffee fermentation; mini-bioreactor; gas-exhaust.