Fabrication of Antioxidant and Antimicrobial Pullulan/Gelatin Films Integrated with Grape Seed Extract and Sulfur Nanoparticles

Biopolymer-based functional blend films were prepared using pullulan and gelatin with functional fillers of sulfur nanoparticles (SNPs) and grape seed extract (GSE). A mixture of pullulan/gelatin (1:1) produced a compatible but slightly translucent free-standing film. SNPs capped with enoki mushroom extract and GSE were added as functional fillers to improve the properties (physical and functional) of the pullulan/gelatin-based film. The addition of SNP and GSE significantly (p < 0.05) boosted the UV-light barrier, water vapor barrier, and oxygen barrier properties of the pullulan/gelatin films. The mechanical performance of the pullulan/gelatin-based films was slightly decreased (∼10%), whereas the addition of fillers did not significantly affect the hydrophobicity and thermal stability. The addition of SNP provided the antimicrobial function against foodborne pathogenic bacteria, L. monocytogenes and E. coli, while GSE provided a powerful antioxidant activity to the pullulan/gelatin-based film. Therefore, pullulan/gelatin-based composite films with better UV, water vapor, and oxygen barrier properties and enhanced antioxidant and antibacterial properties are expected to have high utility in active food packaging applications.