From Waste to Resource in Coffee, Cocoa, Tea and Coconut Industries: Emerging Pathways for Sustainable Biorefineries

Abstract

Agro-industrial residues from coffee, cocoa, tea and coconut production are chemically diverse resources whose management is increasingly framed through biorefinery and circular-bioeconomy concepts. Yet the technical possibility of converting a residue into a marketable product does not establish that the pathway is environmentally preferable, economically robust or operationally scalable. This critical narrative review evaluates emerging valorisation routes across the four industries, with emphasis on feedstock architecture, selective fraction recovery, biochemical conversion, thermochemical and materials pathways, process integration, techno-economics and life cycle performance. Peer-reviewed literature published from 2000 to 15 July 2026 was considered, with older work retained only when conceptually necessary. Evidence was appraised for feedstock characterisation, experimental scale, process intensity, mass and energy implications, product quality, environmental assessment and translational relevance. The synthesis indicates that no universal cascade applies across these commodities. Coffee residues, especially spent coffee grounds, have the comparatively strongest evidence for integrated multi-product schemes and for explicit techno-economic and environmental assessment, although solvent, steam and collection burdens remain important. Cocoa pod husk offers credible opportunities for pectin, phenolics, fermentation products and carbon materials, but drying and electricity demand can materially influence performance. Tea waste supports polyphenol recovery, biological treatment and carbon-material applications, while integrated scale-up evidence remains limited. Coconut shell and husk are particularly well suited to thermochemical conversion, adsorbents and lignin-centred routes, but catalytic intensity, ash, activation chemistry and feedstock heterogeneity can offset apparent advantages. Across all four industries, the most defensible biorefinery strategy is context-specific: it should preserve optionality for high-value fractions without creating disproportionate utility demand, match residual solids to robust conversion routes, and be tested through coupled mass balances, techno-economic analysis and life cycle assessment. Future progress depends less on expanding lists of possible products than on demonstrating integrated, safe and location-specific systems at pilot and commercially relevant scales.