Microbial and chemical dynamics during self-induced anaerobic fermentation of Amazonian Robusta coffee: Implications for process control and product quality.

This study investigated the effects of self-induced anaerobic fermentation (SIAF) on the microbial profiles and chemical composition of Amazonian Robusta coffees, specifically apoatã, clone 025, and clone 08, during a 21-day fermentation period. Microbial diversity was determined using Next-Generation Sequencing (NGS), and the chemical profile was analyzed by chromatography (HPLC and GC/MS) and NMR. A complex microbiota was observed, including B. cereus in all fermentations, K. humilis in clones 025 and 08, Fusarium and Kurtzmaniella in apoatã. Apoatã showed the highest fungal diversity; however, the predominance of undesirable microorganisms after 6 days of fermentation indicates a critical control point for preventing quality loss. Clone 08 showed high bacterial diversity. Clone 025 showed higher ethanol production (5.10 g·kg-1), lactic acid (5.45 g·kg-1), and total volatile compounds (605.1 mg·kg-1), with higher concentrations of 2-nonanol (79.7 mg·kg-1) and methyl salicylate (59.1 mg·kg-1) at the end of fermentation. Clone 08 showed the highest concentration of chlorogenic acids (15.83 g·kg-1) and phenol contents in 21 days. Apoatã showed higher acetate production in 21 days. The main volatile classes were alcohols and esters. These findings highlight the importance of genotype selection and control of fermentation time to optimize product quality and standardize Amazonian Robusta processing.