Fabrication and characterization of polyvinyl alcohol/sodium alginate/zein/ chitosan bilayer film for dynamic visualization of pork quality

The development of real-time and convenient meat freshness indication technology is crucial to ensure food safety. A novel antibacterial visualized intelligent film was designed based on polyvinyl alcohol (PA), sodium alginate (SA), zein (ZN), chitosan (CS), alizarin (AL) and vanillin (VA) using layer-by-layer assembly (LBL) method for real-time and in situ monitoring of pork freshness. The fabricated film had various advantageous properties, including an excellent hydrophobicity with a water contact angle (WCA) of 91.59°, improved color stability, excellent water barrier properties and increased mechanical performance (TS = 42.86 MPa). The fabricated film also demonstrated effective antibacterial properties with a bacteriostatic circle diameter of 13.6 mm for Escherichia coli. Moreover, the film can perceive and visualize the antibacterial effect through color changes, enabling dynamic visual monitoring of the antibacterial effect. A good correlation (R2 = 0.9188) between the color changes (ΔE) and total viable count (TVC) of pork was documented. Conclusively, fabricated multifunctional film improves the accuracy and versatility of freshness indication and had great potential for food preservation and freshness monitoring. The outcomes of this research provides a new perspective for the design and development of multifunctional intelligent films.