Schiff-base crosslinked gelatin-mycosporine-like amino acids/dialdehyde starch composite film: a UV-resistant, biodegradable food packaging material

• Extraction process of MAAs from Porphyra yezoensis was optimized. • MAAs was incorporated into Gel to function as UV-resistant agents. • Molecular docking showed amide cross-linking between Gel and MAAs. • Schiff base reaction was employed to cross-link Gel-MAAs with DS dynamically. • Gel-MAAs/DS films achieved nearly 100 % UV-blocking efficiency. UV-induced photo-oxidation significantly contributes to food deterioration, while conventional petroleum-based packaging demonstrates inadequate resistance to UV radiation. Therefore, the development of UV-resistant biodegradable food packaging has become an urgent problem. In this study, a UV-resistant biodegradable packaging film was successfully fabricated. Mycosporine-like amino acids (MAAs) which are recognized as the strongest natural UV absorbers, were grafted onto gelatin. Molecular docking, UV spectroscopy, FTIR spectroscopy, and CD spectra were performed to analyze the structural characteristics of Gel-MAAs. Subsequently, Gel-MAAs and dialdehyde starch were dynamically cross-linked based on Schiff base reaction using a solution casting method. The physicochemical properties, UV resistance, biocompatibility, and fruit preservation capabilities of Gel-MAAs/DS composite films were then investigated. The experimental results indicated that Gel-MAAs/DS composite films exhibited excellent mechanical properties and UV resistance, achieving a nearly 100 % UV-blocking rate. Under high-intensity UV radiation, the survival rate of probiotics encapsulated by the composite film exceeded 75 %, in contrast to less than 10 % for those wrapped in polyethylene film. Cytotoxicity assays demonstrated the excellent biocompatibility of the composite film. Furthermore, Gel-MAAs/DS composite films effectively preserved the appearance of strawberries, significantly extending their shelf life. Consequently, Gel-MAAs/DS composite films provide effective protection against food deterioration caused by photo-oxidation, representing a promising UV-resistant biodegradable material for food packaging.