Dendrobium devonum juice modulates aroma formation in coffee cherry husks processing: insights into key pathways and flavour enhancement

Coffee cherry husk (CCH), accounting for 40–50% of the coffee cherry mass, is a polyphenol- and fibre-rich by-product with untapped potential. However, its commercial use is limited by pronounced bitterness, inconsistent composition, and suboptimal extraction efficiency. This study evaluated the impact of roasting CCH from Fei Pica coffee (Baoshan, China) with Dendrobium devonum juice as a natural flavour modulator under three thermal regimes (180–220 °C, 6–12 min). Comprehensive characterisation—including physicochemical parameters, antioxidant capacity, and volatile profiling via HS-SPME–GC–MS after hot water/ethanol extraction—showed that higher roasting severity reduced native bioactives (e.g. phenolics, flavonoids, and caffeine). Antioxidant activity initially increased but declined sharply at 220 °C, yielding net pro-oxidant effects. Volatiles were primarily alkanes and aromatics, with Dendrobium devonum juice incorporation significantly enhancing aroma complexity. The results confirm that controlled thermal processing combined with DDJ offers a viable strategy to transform CCH into high-value, functional food ingredients aligned with circular economy principles.