Food waste and fashion pollution are two of the most prominent global environmental issues. To alleviate the problems associated with food waste, while simultaneously contributing to sustainable fashion, the feasibility of making an alternative textile material with leather-like properties from fungal biomass cultivated on bread waste was investigated. The filamentous fungus, Rhizopus delemar, was successfully grown on waste bread in a submerged cultivation process, and fungal biomass was treated with vegetable tannin of chestnut wood. NMR and FTIR confirmed interactions between tannin and fungal biomass, while OM, SEM and AFM visualised the changes in the hyphae upon the tannin treatment. Thermal stability was assessed using TGA analysis. The wet-laid technique commonly utilised for paper-making was used to prepare sheets of hyphae. Some of the sheets were treated with glycerol and/or a biobased binder as post-treatment. Overall, three of the produced materials exhibited leather-like properties comparable to that of natural leather. Sheets from untreated biomass with only glycerol post-treatment showed a tensile strength of 7.7 MPa and an elongation at break of 5%. Whereas sheets from untreated biomass and tannin treated biomass with both glycerol and binder treatments led to tensile strengths of 7.1 MPa and 6.9 MPa, and the elongation at break of 12% and 17%, respectively. The enhancement of hydrophobicity after the binder treatment, helped to preserve the absorbed glycerol within the sheet and thereby the flexibility was retained when in contact with moisture. These findings demonstrate that bread waste-derived fungal sheets have great potential as environmentally friendly materials with leather-like properties.

Despite being considered a premium material, leather poses both environmental and ethical issues. Thus, sustainable alternatives such as vegan leather are in high demand. Therefore, in this study, we aimed to produce vegan leather using vegetable tannins and fungi grown on bread waste. Fungal cultivation was carried out in a bubble column bioreactor using nutrients extracted from bread as substrate. To obtain tanned biomass, the biomass was subjected to vegetable tanning (using Tara, Myrobalan, Chestnut, and Indusol ATO tannins). A mild alkali treatment isolated the fibrous cell wall material from fungal biomass. Different composite sheets were prepared by wet-laying the tanned biomass and cell wall material and placing them in a multilayer arrangement. The composites were post-treated with glycerol and a bio-based binder to improve their mechanical properties. Myrobalan-tanned biomass composites after glycerol and bio-based binder post-treatments had the highest flexibility of 14.8% elongation at break, and Tara-tanned biomass composites had the highest tensile strength of 20.5 MPa. Ashby’s chart demonstrates the relationship between the sheets produced and natural leather. SEM was used to demonstrate the softer and smoother morphologies of the Chestnut and Indusol ATO-tanned composite sheets after post-treatment. Overall, this study presents multilayer fungal biocomposites as a promising vegan alternative leather.

Co-culturing fungi offers a promising strategy for generating hybrid fungal biomass with structural and functional properties for developing fungal-based alternative leather. In this study, two filamentous fungi, Aspergillus oryzae and Rhizopus delemar, were co-cultured to valorise food waste through production of fungal materials with enhanced mechanical properties owing to chitin-rich biomass of A. oryzae and chitin-chitosan-rich biomass of R. delemar. After confirming symbiotic growth on solid media and in submerged semi-synthetic media, the system was applied to a complex medium prepared from bread and lemon waste. Cultivation was scaled up to a 4.5 L bubble-column bioreactor. The harvested biomass was tanned with chestnut tannin and processed into materials using wet-laid method. Symbiotic growth was verified by polymerase chain reaction (PCR) amplification and visually via optical and scanning electron microscopy (SEM). Unlike the pelletised morphology typical of A. oryzae, the co-culture produced dispersed mycelium favouring material formation. Co-cultures yielded higher ethanol concentrations (12–14 g/L), with biomass yields exceeding those of R. delemar (~0.2 g/g) and comparable to A. oryzae (~0.3 g/g) monocultures. The highest tensile strength and elongation achieved were 11.7 MPa and 8% respectively. Overall, this work establishes fungal-fungal co-culture as a transformative approach for producing hybrid biomass for fungal-based leather alternatives.