Material properties and antimicrobial activities of starch/PBAT composite films incorporated with ε-polylysine hydrochloride prepared by extrusion blowing

In this study, starch/PBAT antimicrobial films with different ε-polylysine hydrochloride (ε-PL) contents (0, 1, 2, 3, and 4 wt%) were developed by extrusion blowing. Rheological results indicated that incorporation of ε-PL decreased the complex viscosity and storage modulus of blends. Fourier transform infrared spectra revealed that intermolecular hydrogen bonds were formed between ε-PL and starch. The incorporation of ε-PL enhanced thermal stability, ultraviolet barrier and oxygen barrier properties of the films; however, the composite films had heterogeneous microstructures with decreased surface hydrophobicity, moisture barrier, and mechanical properties. Antimicrobial activity of the films increased with increasing ε-PL contents; at 4 wt% ε-PL level, the growth of all tested microorganisms (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) was effectively inhibited. The ε-PL containing starch/PBAT blown films are promising as an antimicrobial packaging material for delaying food spoilage.