Eco-friendly Smart Packaging Film with High Thermal Stabilities, Antibacterial Activities, and Food Freshness Monitoring

Traditional polysaccharide-based films, though environmentally friendly, face challenges like poor heat resistance and susceptibility to bacterial contamination, limiting their application in bio-based and smart food packaging. This study presents a novel composite film by incorporating zinc ions (Zn²⁺) into hydroxypropyl methylcellulose (HPMC) and sodium alginate (SA). This HPMC/zinc-alginate (ZA) film aims to address these limitations. The study investigates the microstructure, physicochemical properties, thermal stability, antimicrobial efficacy, pH responsiveness, and food freshness monitoring performance of films. Fourier-transform infrared spectroscopy (FTIR) identified enhanced hydrogen bond interactions among Zn²⁺, curcumin, and the film matrix. X-ray diffraction (XRD) analysis revealed superior crystallinity, and thermogravimetric analysis (TGA) confirmed improved thermal stability. The Zn²⁺ addition provided 99.99% antibacterial effectiveness against S. aureus and E. coli. The HPMC₅/ZA₅-Cur_3% film effectively monitored food quality by changing color as food deteriorated. This research supports the development of natural, edible packaging films with enhanced safety and monitoring capabilities, marking a significant advance in smart food packaging technology.