Smart halochromic platform based on a gelatin film reinforced by a novel nanofluid-anthocyanin complex for monitoring protein food freshness

• Innovative green nanofluid for eco-friendly anthocyanin extraction from jumbo fruit. • Nanofluid includes hafnium MOFs and choline chloride:glycerol (Ch:Gl/Hf MOF:NF) • Ch:Gl/Hf MOF:NF effectively extracts anthocyanins and modifies gelatin hydrogel. • Creative integration of Ch:Gl/Hf MOF:NF with gelatin enhances mechanical properties. • Enhanced antibacterial and diffusion properties are due to the Hf MOF component. • Unique inorganic-organic nanocomposite enables real-time fish freshness detection via color change. Herein, an innovative gelatin nanocomposite designed as a pH-colorimetric platform for protein food freshness monitoring. In this platform gelatin incorporated with a new nanofluid-anthocyanin complex which comprises hafnium metal-organic frameworks (Hf MOF), choline chloride:glycerol (Ch:Gl) natural deep eutectic solvent, and crude anthocyanin extract from Iranian Jumbo fruit (JAE). This nanofluid (NF) serves multiple functions: a green solvent for anthocyanin extraction, boosts the gelatin hydrogel sensing film, amplifies color changes, and stabilizes the anthocyanin molecules. The environmentally friendly NF based extraction, eliminating additional separation steps for anthocyanin, allowing for direct introduction of mixture into the gelatin hydrogel. The nanoplatform showed a significant color shift when exposed to ammonia, and changing from pink (fresh) to green (spoiled) during storage of fish at 4°C. Integrating Ch:Gl/Hf MOF:NF into gelatin film enhanced its mechanical and antibacterial properties. This platform meets essential criteria for smart, durable, and stable sensing film, for intelligent food packaging.