A Highly Hydrophobic Sustainable Starch/Gelatin-Beeswax Biodegradable Film: Easy to Industrial Scale-Up, Recyclable, and Suitable for Multiple Packaging Application Scenarios

Polysaccharides-based sustainable and biodegradable packaging materials suitable for variable conditions are potential candidates for replacing petroleum-based polymers. However, the poor hydrophobicity of polysaccharide films seriously limits their practical applications. Inspired by the phase separation of pseudobilayer films through solution-method casting, a novel and facile strategy for preparing highly hydrophobic starch/gelatin-beeswax (HSGBW) film was developed using an extrusion blowing method suitable for industrial production. The increased extrusion blowing temperature enhanced the interaction between starch and gelatin (originally used to stabilize beeswax), leading to the destabilization of beeswax and its migration to the film surface, ultimately resulting in the formation of a wax-enriched hydrophobic layer. The resultant HSGBW film exhibited excellent hydrophobicity (water contact angle: similar to 106 degrees), outperforming starch-based materials reported to date as well as outstanding water resistance, UV-blocking, self-cleaning ability, moisture, oxygen, and oil barrier properties. The HSGBW film also exhibited excellent biosafety, storage stability, rapid dissolution at high temperatures (which offers convenience for packaging certain foods that expediently require high-temperature boiling), fully biodegradable performance, and easy recyclability. Owing to these multifunctional properties, the resulting film was applied in inner food packaging under different scenarios, as evidenced by the packaging of foods with high moisture content (cucumber dumpling stuffing), high fat content (high-fat powdered milk), and high oil content (chili oil seasoning). From ecological and convenience viewpoints, this work demonstrated a facile strategy for manufacturing HSGBW film for packaging materials to replace petrochemical-derived plastics in many fields, especially inner food packaging, providing new opportunities for starch-based sustainable material designs.