Chitosan‑titanium dioxide emulsion incorporated pH-responsive active packaging film: Real-time freshness monitoring and targeted fishy odor control

Abstract

This study developed a multifunctional smart packaging film by integrating chitosan‑titanium dioxide-stabilized perilla essential oil Pickering emulsion and curcumin (Cur) into a gelatin matrix. The resulting film exhibits active preservation capabilities and pH-responsive indicator functions. Fourier transform infrared spectroscopy confirmed good component compatibility. Cur addition (0-1.6 mg/g) significantly enhanced film properties: at 1.2 mg/g, ultraviolet blocking improved, water solubility decreased to 24.65 %, water vapor permeability was reduced, maximum degradation temperature increased to 321 °C, and elongation at break rose to 29.61 %. The film showed broad-spectrum antibacterial properties in vitro and excellent antioxidant activity. Cur endowed it with sensitive, reversible pH responsiveness, with color shifting from yellow to red in alkaline amine gases. During fish meat preservation at 4 °C, the E-Cur-1.2 film (Cur 1.2 mg/g) inhibited spoilage bacteria through a multi-component synergistic effect, delayed protein and lipid oxidation, and reduced aldehyde/ketone volatiles with unpleasant odors. The film color parameters and total volatile basic nitrogen have a strong correlation (R² > 0.95), enabling real-time freshness monitoring. This study provides innovative strategies and theoretical support for high-performance gelatin-based smart packaging for aquatic products.

Keywords: Antibacterial; Bio-based multifunctional packaging; Colorimetric indicator; Deodorization; Freshness.