Protein Nanofibrils as Emerging Biomaterials for Sustainable Food Packaging: Advances, Challenges, and Future Opportunities.

The transition toward sustainable food packaging has driven intensified research into bio-based materials capable of reducing dependence on conventional plastics. Functional amyloid protein nanofibrils (PNFs) have emerged as a novel class of supramolecular biomaterials owing to their highly ordered β-sheet-rich structures. PNFs can be derived from multiple protein sources, including dairy, plant, egg, and underutilized agro-industrial protein sources, thereby supporting resource valorization and integration into the circular bioeconomy. PNFs exhibit great mechanical strength, barrier properties, and intrinsic biocompatibility. This review systematically analyzes recent advances in PNF-based materials for food packaging applications. It covers fundamental aspects of PNF molecular structure, self-assembly mechanisms, and fibrillation kinetics, along with fabrication and film-forming strategies. The influence of processing routes on mechanical, thermal, and barrier properties is critically discussed. In addition, emerging approaches for imparting active and smart functionalities are evaluated. It also identifies and covers the core challenges to scaling up production, safety, regulation, and public perception, and map out pathways for industrial adoption. PNF-based films exhibit outstanding mechanical performance and gas barrier properties, often exceeding those of conventional biopolymer packaging materials, while maintaining biodegradability. Despite these advantages, industrial translation is limited by processing efficiency and regulatory uncertainties. Future research should focus on scalable continuous fibrillation, low-cost protein side streams, hybrid composite systems, bioactive/smart functionalities, pilot-scale validation, and circular economy approaches for next-generation edible and biodegradable packaging solutions.