The Antioxidant and Antibacterial Properties of Honeycomb-Structured Polylactic Acid/Astaxanthin@ZIF-8 Bio-Composite Film Applied in Beef Preservation

Abstract

Food spoilage is mainly driven by lipid oxidation and microbial proliferation. To counteract these challenges, multifunctional protective films have emerged as effective solutions for suppressing both reactions. In this work, biodegradable polylactic acid (PLA) was selected as the polymer matrix to fabricate composite films. Colloidal ZIF-8 nanoparticles loaded with the natural antioxidant astaxanthin (AST) were mixed with PLA. By precisely controlling temperature and humidity during the solution-casting process, a honeycomb-structured PLA/AST@ZIF-8 composite film was successfully prepared. The structural and physico-chemical properties of the as-prepared film were systematically characterized by FE-SEM, FTIR, Raman, XRD, and TGA. The results confirm the formation of a well-defined honeycomb morphology, with AST uniformly dispersed throughout the PLA matrix. Importantly, films with AST content above 2.0% exhibit weak antibacterial properties. Practical application tests for preserving beef tenderloin demonstrate that the film provides excellent antioxidant and antibacterial effects. On the seventh day, the water loss, pH, ΔE and total volatile basic nitrogen (TVB-N) values of beef samples treated with the PLA/ZIF-8/2.5%AST film remained within acceptable thresholds, effectively extending the shelf life of fresh meat. Safety assessments on overall migration (OM) and Zn2+-specific migration confirm that the PLA/AST@ZIF-8 composite film fully complies with EU Regulation No. 10/2011. These results demonstrate the great application prospects of the composite film for high-performance food preservation.