In order to expand the application of polysaccharide coatings in the preservation of aquatic products, sandwich-type composite coatings were prepared using konjac glucan (KGM) and sodium alginate (SA) as coating substrates and thymol (Thy) and ε-poly-L-lysine hydrochloride (ε-PL) as antimicrobial agents and their effects on protein oxidation in fresh salmon fillets were studied during storage at 4 ℃. The results showed that the solubility, sulfhydryl content and Ca²⁺-ATPase activity of myofibrillar protein in the composite coating treated fillets increased, and the carbonyl content and surface hydrophobicity of myofibrillar protein (MP) decreased remarkably compared with those treated with sterile water after the same storage period. In addition, the tertiary and secondary structures of myofibrillar protein in the composite coating treated group was more complete. In the late storage period, the protein oxidation indexes of salmon fillets treated with KGM/SA+ε-PL/KGM+Thy composite coating were better than those of the samples treated with KGM/SA+ε-PL/KGM and KGM/SA+Thy/KGM composite coatings after the same storage period. Therefore, in the sandwich-type KGM/SA/KGM composite coating, ε-PL and Thy could act synergistically to delay protein oxidation and denaturation. The results of this study can provide technical guidance for the application of edible coatings in aquatic product preservation.

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.

Meat has high nutritional value, but it is prone to spoilage during processing, storage and transportation. Thus, it is necessary to monitor the freshness of meat products in real time and quickly detect unqualified meat products. In recent years, the development of intelligent packaging materials to evaluate the freshness of meat products in real time has attracted extensive attention, and intelligent hydrogels have become a research hotspot. In order to provide technical support for the application of intelligent hydrogels in meat products, this paper summarizes the preparation methods of hydrogels, reviews the current status of the application and development of intelligent hydrogels in meat freshness monitoring, and gives an outlook on future trends in this field.