Novel core-shell pullulan-gelatin-zein nanofiber films loaded with nanochitin-nisin complexes for antibacterial food...

Antimicrobial packaging is important for preventing food spoilage and extending shelf life. Herein, antimicrobial core-shell nanofiber films were fabricated via coaxial electrospinning with pullulan/nanochitin-nisin complexes as the core and gelatin-zein as the shell. Particle size and zeta potential analyses confirmed the successful formation of nanochitin-nisin complexes. Fourier-transform infrared spectrometry (FTIR) revealed binding via electrostatic interactions and hydrogen bonding. The suitable viscosity, conductivity, and surface tension of the spinning solutions ensured good spinnability, yielding uniform nanofibers, as observed using scanning electron microscopy. FTIR and X-ray diffraction analyses indicated that hydrogen bonding stabilized the core-shell structure without altering the crystallinity of biopolymers. The resulting films exhibited enhanced thermal stability, mechanical strength, reduced water vapor permeability (by ~40 %), and improved hydrophobicity. The antibacterial activities against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 were comparable to those of uniaxial nanofiber films. After 15 days of refrigerated storage at 4 °C, sea bass fillets wrapped in the films showed reductions in total volatile basic nitrogen, total viable counts, and thiobarbituric acid reactive substances by approximately 50 %, 90 %, and 75 %, respectively, compared to those wrapped in uniaxial nanofiber films. These findings indicate the potential of the core-shell nanofiber films for antimicrobial food packaging applications.