Multi-layered smart film based on anthocyanin-citric acid complex for real-time meat freshness monitoring.

Conventional meat freshness indicator films often lack mechanical strength, environmental stability, and accurate spoilage detection. This study presents a layered design integrating structural reinforcement, molecular stabilization, and interfacial protection. A carboxymethyl cellulose/xanthan gum (CMC/XG) composite enhanced mechanical strength, an anthocyanin-citric acid complex provided stable pH-responsive color change, and a beeswax-sunflower oil coating improved hydrophobicity, forming the CX-BC-BSO multilayer film. The film exhibited high tensile strength (≥28 MPa), strong hydrophobicity (water contact angle >110°), and precise pH response (color rendering error < 5 %). Integrated into a sensing system, it accurately monitored chicken breast spoilage in real time, with over 92 % accuracy in detecting the critical "sub-fresh" stage, outperforming traditional films. This work overcomes single-function film limitations and offers a cost-effective, efficient solution for real-time food freshness monitoring, contributing to food waste reduction.