Characteristics and bioactive functions of chitosan/gelatin-based film incorporated with ε-polylysine and astaxanthin extracts derived from by-products of shrimp (Litopenaeus vannamei)

A biofunctional composite film was prepared using a casting method by incorporation of ε-polylysine (ε-PL) plus astaxanthin (Asta) extracts from Litopenaeus vannamei (L. vannamei) by-products into chitosan and gelatin film forming formulations. Compared with the bare gelatin or the chitosan-gelatin films, the composite film had similar water content and thickness, whereas, decreased water solubility, increased water vapour permeability and water contact angle. Molecular interactions were formed between gelatin and chitosan with or without ε-PL and Asta addition, as recorded and confirmed by X-ray diffraction and Fourier-transform infrared spectroscopy. The scanning electronic microscopy images showed rough cross-section with pores, as well as vertical cracks along the composite film matrix. Surface roughness decrease was observed for the composite film by atomic force microscopy. The composite film displayed strong inhibitory effect (near 100%) against spoilage bacteria derived from L. vannamei. Besides, the lipid oxidation of corn oil was retarded after addition of composite film, with less than 5 nmol/mL of malondialdehyde detected when incubation at 60 °C for 59 h. Therefore, such composite film could have potential applications for antibacterial and antioxidant food packaging material.