Investigation of Fungal Mycelium-bound Bio-foams from Agricultural Wastes as Sustainable and Eco-conscious Packaging Innovations

Abstract

The existing non-biodegradable plastic packaging foams pose significant environmental challenges and contribute to landfill congestion. As a sustainable alternative, bio-foams derived from fungal mycelium (as the bonding agent) and waste biomass (as the substrate) are gaining prominence. In this research, the performance efficiency of bio-foams was assessed using five previously unexplored mycelium species (Coprinopsis macrocephalus, Bjerkandera adusta, Flammulina velutipes, Trametes pubescens, and Trichaptum biforme,) and three frequently used species (Ganoderma lucidum, Pleurotus ostreatus, and Fomes fomentarius). Additionally, the study investigated mycelium-bound biomaterials with and without nutrient supplementation, employing three more mycelium species (Ganoderma lucidum, Flammulina velutipes and Pleurotus ostreatus). The fabrication process employed a mother-culture based method. The assessment included the following aspects of eleven mycelium-bound bio-foams: dry density, growth performance, mechanical properties (support factor, firmness, recovery rate, etc.), moisture content, morphological analysis, shrinkage percentage, thermogravimetric analysis, thickness swelling and water absorption properties. Results indicated that the compressive firmness of various bio-foams ranged from 10.33 to 52.97 kPa, while the commercial packaging foam was 24.48 kPa. Similarly, the density of the mycelium-bound bio-foams ranged from 78.53 to 153.59 kg/m³ compared to commercial packaging foam with a density range from 8 to 120 kg/m³, making bio-foams competitive alternatives. The bio-foams generated from Bjerkandera adusta and Fomes fomentarius exhibited favourable colonisation conditions, a mycelial skin that was strong, thick hyphae, and mechanical properties that were similar to those of typical packing foams. The novel mycelium specie Bjerkandera adusta has intriguing properties that make them prospective candidates for mycelium-bound packing foams, in addition to the widely utilised Ganoderma lucidum, Pleurotus ostreatus, and Fomes fomentarius.