Extrusion-blown biodegradable food packaging films based on starch, gelatin, and polyester blends: A comprehensive review

Growing concerns over plastic pollution have intensified the development of biodegradable films as sustainable alternatives to conventional packaging plastics. Among available manufacturing techniques, extrusion blowing is the most industrially scalable and viable process for producing high-performance films. This review examines recent progress in biodegradable polymers suitable for extrusion blowing, with emphasis on thermoplastic starch (TPS), gelatin, poly(butylene adipate-co-terephthalate) (PBAT), polylactic acid (PLA), and polyhydroxyalkanoates (PHA). Key strategies to address intrinsic limitations such as high hydrophilicity, weak interfacial adhesion, and insufficient mechanical stability include compatibilization, blending, and the incorporation of functional additives. Lipid-based additives improve moisture resistance, nanoparticles enhance mechanical reinforcement, and active agents enable intelligent packaging functionalities. Emerging approaches, such as chemical modification, multilayer and composite structures, further expand opportunities to tailor film performance for food packaging applications. By linking formulation design with processing conditions and end-use performance, this review highlights advances towards scalable and eco-efficient biodegradable films. Despite significant progress, challenges related to large-scale production, cost efficiency, and regulatory alignment remain unresolved. Nevertheless, continued innovation in bio-based and functional materials underscores the strong potential of these films within a circular packaging economy.