Fungal Chitin Nanofibrils to Improve the Functional Properties of Poly(vinyl alcohol) Films for Sustainable Food Packaging

Food packaging films containing biobased fillers can offer improved functional properties while meeting current environmental sustainability requirements for a circular and sustainable society. In this work, biocomposites based on chitin nanofibers and PVA have been developed in order to improve the mechanical performance and water barrier properties, performing for the first time a life cycle assessment. The biocolloids employed are chitin nanofibrils (ChNFs) from fungi, an underutilized renewable carbon feedstock in packaging, which are more environmentally friendly than conventional ChNFs obtained from crustaceans. Free-standing nanocomposite films are obtained by solvent casting, using water as the sole solvent. The incorporation of ChNFs results in a mechanical reinforcing effect of PVA that increases the Young modulus. The water vapor barrier character of PVA is significantly enhanced by the presence of ChNFs, which is decreased by 70% upon the incorporation of 10% ChNFs, overcoming one of the most significant drawbacks of PVA. The nanocomposites maintain an excellent oxygen barrier character under high relative humidity. Life cycle assessment (LCA) reveals a global warming potential of 5.0-5.2 kg·CO₂ equiv·kg^-1 for PVA/ChNFs films, demonstrating clear environmental benefits of the incorporation of ChNFs when considering the final properties. Overall, this work highlights the potential of fungal ChNFs to improve the mechanical properties and significantly improve the water barrier character of PVA, overcoming one of the limitations of this material in a sustainable way, as demonstrated by LCA.