Upcycling banana peduncle fibers into mycelium-based composites for sustainable packaging and thermal insulation

The growing concerns due to plastic pollution in India have intensified the search for sustainable materials. Mycelium-based composites (MBCs) have emerged as bio-based alternatives for packaging and thermal insulation applications. India, the worlds largest producer of bananas, generates significant quantities of banana biomass (~200 tons per hectare per year), much of which remains underutilized. The banana peduncle, the stalk that supports the fruit bunch, is one such underutilized biomass. In this study, banana peduncle fibers were used as the main substrate with Pleurotus ostreatus for the fabrication of MBCs. Banana peduncle fibers were mixed with wood shavings (10-50 wt%) to enhance the dimensional stability and structural integrity of the composites. The properties of developed MBCs such as density, shrinkage, moisture absorption, water absorption, morphology, compressive properties, and thermal conductivity were studied. The 90% banana peduncle fibers-10% wood shavings formulation showed the highest radial mycelial growth rate (7 mm/day). MBCs consisting of 100% banana peduncle fibers had volumetric shrinkage of 36%, while the incorporation of 30-50% wood shavings reduced shrinkage by approximately 17%. Among the formulations, MBCs containing 30% wood shavings had the highest compressive strength (4.82 MPa) and compressive modulus (1.78 MPa), whereas MBCs containing 50% wood shavings had the highest recovery (59.6%). In contrast, MBCs fabricated using 100% banana peduncle fibers had the lowest thermal conductivity (0.04 W/m. K). These results demonstrate that banana peduncle fibers are a promising lignocellulosic substrate for the development of MBCs for sustainable packaging and thermal insulation.