Unlocking the Quality Potential of Liberoid Coffee: Advances in Composition, Processing, and Microbial Fermentation

Liberoid coffee (Coffea liberica group), comprising varieties of Liberica and Excelsa coffee types, is gaining attention for its unique chemical composition and sensory potential. However, its quality remains under-optimized due to limited understanding of genotype-specific traits and processing responses. This review synthesizes recent findings on the proximate composition, bioactive compounds, and volatile profiles of Liberoid coffee, highlighting key differences from Arabica and Robusta. Emphasis is placed on the role of post-harvest processing, particularly in vitro fermentation using defined microbial starters, in modulating flavor precursors, reducing alkaloids, and enhancing Maillard reaction products. Liberoid beans' special chemical and physicochemical properties, coupled with their thick pulp and low bean yield, necessitate tailored processing strategies. Controlled fermentation offers a promising route to improve mouthfeel, reduce bitterness, and develop differentiated flavor profiles. Future research should prioritize microbial safety, fermentation optimization, and genotype-specific processing to support the development of high-quality Liberoid coffee with consistent sensory and functional attributes.