Interaction Among Microbiota, Chemical Composition, and Quality Variations in Coffea arabica Across Altitudinal...

Area of Science:

• Agricultural Science
• Microbiology
• Food Chemistry

Background:

• Planting altitude critically impacts coffee flavor, but the underlying microbial and chemical mechanisms during wet processing are not fully understood.
• Wet processing involves fermentation, a microbial-driven step that transforms coffee bean composition and flavor precursors.

Purpose of the Study:

• To investigate how different planting altitudes (1000m-1600m) influence microbial diversity during coffee wet processing.
• To analyze the corresponding changes in non-volatile and volatile compounds in coffee beans at various altitudes.
• To correlate these changes with the final flavor profile and cupping scores of roasted coffee.

Main Methods:

• Systematic sampling of coffee beans across four altitudes during wet processing.
• Microbial community analysis to identify dominant bacterial and fungal genera.
• Chemical analysis of non-volatile and volatile compounds using chromatography and mass spectrometry.
• Sensory evaluation of roasted coffee beans through cupping scores and descriptive analysis.

Main Results:

• Fermentation shifted dominant bacteria from Sphingomonas/Pleomorphomonas to Weissella/Lactobacillus, with Cladosporium/Fusarium remaining dominant fungi.
• Significant differences in non-volatile and volatile compounds were observed across altitudes, with higher altitudes showing more differentially changed compounds.
• Cupping scores increased with altitude, with the highest altitude (1600m) exhibiting superior sweetness, nutty, and flowery notes, linked to specific volatile compound variations.

Conclusions:

• Planting altitude is a key determinant of coffee flavor, mediated by microbial dynamics and chemical transformations during wet processing.
• High-altitude Arabica coffee cultivation fosters distinct microbial communities and chemical profiles, leading to enhanced sensory attributes.
• These findings support the potential of high-altitude environments for producing specialty-grade coffee with superior flavor profiles.