pH-triggered zein/chitosan/Eudragit L100 film with intelligent sequential vanillin release for beef preservation

pH-sensitive controlled-release antimicrobial film was developed based on a zein-chitosan-Eudragit L100 matrix encapsulating vanillin (designated as ZCLV), aiming to provide sustained antimicrobial protection over the food storage phase, especially during the initial acidic spoilage period. The physical properties, microstructure, and proton-motive release behavior of film were thoroughly characterized. The ZCLV film exhibited superior moisture barrier properties, with a water vapor permeability (WVP) of 3.64 × 10^-5 (g·m^-1·s^-1·Pa^-1). It also demonstrated a high encapsulation efficiency (EE) of 53.82% and a loading content (LC) of 9.26%. Under test conditions at 4 °C, the ZCLV film provided an initial microbial reduction of 0.44 log cfu/g and sustained antibacterial activity, extending the shelf life of beef by 3 days. The dual pH-responsive release mechanism of the ZCLV film enables intelligent sequential release of vanillin that dynamically adapts to pH changes during beef spoilage, thereby achieving prolonged preservation.