Insights into the structure, physical properties and degradation characteristics of sesame leaf protein-based bionanocomposite packaging films: Focus on the regulatory effects of corn starch and potato starch

Sesame leaves, often discarded as agricultural byproducts, are a nutrient-dense yet underutilized protein source (∼32 % protein), offering potential for sustainable food packaging. This study successfully extracted sesame leaf protein (SLP) and cellulose nanocrystals (CNC) from sesame leaves to fabricate nanocomposite films with corn/potato starch (CS/PS). The film-forming liquid showed decreased but stable zeta potential (>26 mV) after starch addition. Fluorescence attenuation was observed in the film-forming solution, as with increasing starch content, a more compact tertiary conformation formed in the film-forming solution, which shielded the tryptophan residues in the SLP. The increase in starch content effectively promoted the conversion from α-helix to β-sheet structure, while simultaneously enhancing intermolecular hydrogen bonding and significantly improving film crystallinity. SLP/CNC/CS exhibited superior mechanical strength, UV-blocking and barrier properties. SLP/CNC/CS and SLP/CNC/PS demonstrated excellent biodegradability and enhanced soil bacterial diversity. Furthermore, the developed film effectively extended the shelf life of blueberries.