Mycelium-Based Biocomposites as Sustainable Polymer Alternatives: Engineering Strategies, Structure–Property Relationships and Circular Packaging Applications

Mycelium-based composites (MBCs) represent a new class of bio-based polymer alternatives, where fungal networks act as natural binders within lignocellulosic composite architectures. This review systematically summarises the development of mycelium-based packaging materials from early laboratory research to industrial applications since the pioneering work of Ecovative Design in 2007. The review analyses how fungal strains and substrate compositions regulate the mechanical properties, density, hydrophobicity, and biodegradability of MBCs. Additionally, reinforcement strategies, including natural fibre reinforcement, nanomaterial modification, densification treatment, and process optimisation, are discussed for their roles in improving material performance. Furthermore, current commercial applications of mycelium-based packaging in electronics, food, cosmetics, and construction are reviewed, together with the major challenges limiting large-scale industrialisation, such as production scalability, cost competitiveness, and batch variability. Future research directions, including strain engineering, intelligent living materials, and automated biomanufacturing, are also outlined. Overall, this review provides a comprehensive reference for the design, optimisation, and commercial development of mycelium-based packaging materials within the framework of a circular bioeconomy.