Preparation of Pullulan Polysaccharide/Thermoplastic Polyurethane Coaxial Electrospinning Film with Oregano Essential Oil as Core Material and Its Preservative Effect on the Quality of Lateolabrax japonicus Fillets

The use of plant essential oils as an antibacterial agent for food packaging has become a new trend. In order to obtain biodegradable films for the preservation of aquatic products, coaxial electrospinning films were prepared by electrospinning using the antimicrobial preservative oregano essential oil (OEO) or its main components as core material, pullulan (Pul) as film-forming substrate, and thermoplastic polyurethane (TPU) as shell material and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy. Also, its thermal stability, physicochemical properties was determined as well as the release performance of the antimicrobial preservative from the coaxial electrospinning films and its efficacy in preserving the quality of refrigerated Lateolabrax japonicus fillets. The results showed that OEO was effectively encapsulated in the electrospinning fibers, improving the micromorphology, water vapor barrier properties and wettability and significantly reducing the tensile strength (TS), and swelling degree (SD) of the film (P < 0.05), but not changing the thermal stability of the film significantly. The fibers inside the film had a coaxial core-shell structure, and the release behavior of the preservative was a complex coupling of disintegration and dissolution, resulting in controlled OEO release for up to 60 h. In addition, the film effectively inhibited the growth of microorganisms, and thus had excellent preservative effect on fresh L. japonicus fillets. It effectively delayed the deterioration of the smell, texture and apparent quality of the fillets, and extended the shelf life from 8 to 12 d. This study can provide a theoretical basis and technical support for the development of biodegradable antibacterial packaging materials based on biological antibacterial agents.