From climate stress to cup quality: Implications for fermentation and starter cultures in Robusta coffee

Global Robusta coffee ( Coffea canephora ) production is increasingly challenged by climate change, which alters temperature, water availability, and seasonal patterns, with potential consequences for cherry biochemical composition, microbial dynamics, and cup quality. While fermentation is a recognized quality driver, this review integrates the traditionally separate domains of climate-induced stress, microbial ecology, and metabolite stabilization to analyze the shifting microbiome as a dynamic biological risk factor. It is argued that the inherent instability of the Robusta microbiome, potentially amplified by thermal acceleration of metabolic activity and the species' characteristic thick mucilage, may render spontaneous fermentation an increasingly unreliable method for quality assurance. Recent evidence suggests that controlled fermentation using selected yeasts and bacteria can overcome these disruptions by imposing metabolic dominance and stabilizing sensory outcomes. To address remaining gaps in integrating microbial ecology with real-world climate impacts, we also propose a unique multi-stage translational roadmap to bridge the gap between laboratory-scale strain discovery and practical on-farm implementation. By combining adaptive strain selection with socio-technical integration, this framework offers a proposed scalable pathway to enhance Robusta’s quality and resilience, transforming it into a climate-adaptive product.