Protein amyloid fibrils for sustainable food packaging: From structural design and functional enhancement to preservation performance: A review.

Conventional petroleum-based food packaging exhibits poor biodegradability, contributing to microplastic pollution and fossil resource depletion and prompting the development of sustainable alternatives. However, the limited mechanical and barrier properties of many biopolymers restrict their practical applications. Protein amyloid fibrils, with highly ordered cross-β-sheet structures, excellent film-forming ability, and high mechanical strength, provide a promising multifunctional platform for biodegradable food packaging. This review highlights recent advances in amyloid fibril-based packaging and coatings, focusing on their preparation, characterization, safety, and structure-function relationships. Amyloid fibrils act as reinforcing agents and functional delivery carriers, while their dense hydrogen-bond networks and β-sheet architectures improve the mechanical strength, toughness, and gas and water vapor barrier properties of biopolymer matrices. They can also contribute to antioxidant and antibacterial activities and enable the sustained release of essential oils, polyphenols, and metal ions. These properties support their application in packaging films, edible coatings, functional composites, and smart packaging systems for fruits, vegetables, meat, and aquatic products, helping delay food spoilage, browning, moisture loss, and quality deterioration. Nevertheless, fibril aggregation, poor moisture stability, high production costs, limited scalability, and insufficient long-term safety data remain major challenges. Future efforts should focus on scalable production, multifunctional composites, stimuli-responsive systems, and comprehensive safety evaluation.