In a recent paper in Scientific Reports, researchers present a method to develop a biobased material that has similar properties to conventional leather. The basis of this material is fungal biomass, grown on bread waste. The study contributes to the search for more sustainable and circular alternatives to animal and synthetic leather.
The research team used surplus bread as a nutrient medium for the filamentous fungus Rhizopus delemar. This fungus is often used in biotechnological applications because of its fast growth and ability to thrive on cheap substrate flows. After a few days of fermentation, a fibrous biomass is created, which is then processed into a biocomposite.
In order to improve the properties of this biomass, the scientists investigated various vegetable tanning agents – including tara, myrobalan, chestnut extract and Indusol ATO – which are also commonly used in the leather industry. These agents influence, among other things, the strength, flexibility and moisture resistance of the final material.
Multilayer biocomposites
The production of the bio-based 'leather' consists of several steps. First, the fungal biomass is treated physically and chemically and mixed with a binder and plasticizer (including glycerol) to increase flexibility. Then, multi-layered sheets are assembled that feel and perform like conventional leather.
The combination of tanning agent and post-treatment proved to have a major influence on the material properties. For example, with tara a tensile strength of 20,5 MPa was achieved, and with myrobalan a deformability of almost 15% before breakage. These are values that are within the range of natural leather, which, depending on the type and processing, has a tensile strength between approximately 10 and 25 MPa.
Sustainability aspects
An important advantage of this method is that it uses a residual flow from the food industry, in this case old bread. This means that the process is in line with the principles of the circular economy: revaluing waste into raw materials for high-quality applications. Furthermore, the production process is free of heavy metals and synthetic chemicals that are often used in traditional leather production.
The biodegradability of the material was also investigated. After composting under controlled conditions, the biocomposites showed clear degradation phenomena, indicating a favourable environmental profile after use.
Potential and next steps
According to the researchers, the results offer starting points for further development and scaling up. There is increasing demand for plant-based alternatives to leather, particularly in the fashion, furniture and packaging industries. However, there are still challenges, such as scalability, reproducibility and costs.
The research is still in the experimental phase, but shows that it is possible to create a sustainable material with relatively simple means that is comparable in appearance and performance to leather. Whether and when this type of biocomposite becomes commercially applicable depends on further optimization and the willingness of industries to embrace biobased alternatives.
Link to the research Nature.com
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