Multifunctional layer-by-layer smart film with betalains and selenium nanoparticles for intelligent meat freshness monitoring and preservation.

Multifunctional pH-responsive films were fabricated via layer-by-layer deposition of gelatin, chitosan, and carboxymethyl cellulose (CMC), incorporating selenium nanoparticles (SeNPs) and beetroot extract (BTE), to monitor and preserve beef freshness. SeNPs were synthesized and characterized via various techniques. BTE exhibited promising functional properties, and films demonstrated a significant color transition from red to yellow across pH 2-14. SeNPs and BTE incorporation enhanced UV resistance, mechanical properties, and reduced water and oxygen permeability. AFM revealed distinct changes in film surface morphology upon the addition of SeNPs and BTE. The films displayed strong antibacterial and antioxidant activities, making them suitable for food packaging applications. Molecular docking simulations indicated strong binding affinities between betalains and gelatin, while CMC stabilized the multilayer structure. These multifunctional films extended beef shelf life and monitored its freshness by transitioning film color upon spoilage, introducing novel nanoparticle-incorporated multilayer films for intelligent packaging and effective preservation of animal-derived food freshness.