All-natural sodium alginate films reinforced with Rana chensinensis ovum protein isolate/xanthan gum-stabilized Pickering emulsions for active preservation and freshness indication

To address food spoilage and real-time monitoring, an all-natural multifunctional composite film was developed by incorporating Rana chensinensis ovum protein isolate/xanthan gum–lemon essential oil (RCOPI/XG-LEO) Pickering emulsion and anthocyanins, achieving active preservation and visual sensing. The Pickering emulsion with excellent stability enhanced the film hydrophobicity and thickness, while reducing water content (WC) and moisture absorption (MA). The film achieved optimal performance at an emulsion addition of 2 mL. The soil degradation rate reached 60.89% within four weeks, demonstrating strong antioxidant effects (DPPH 61.84%, ABTS 81.58%), antibacterial activity against E. coli and S. aureus , and low UV transmittance (8.56%) in the 200–400 nm range. The incorporation of anthocyanins imparted pH-responsive properties. In banana and pork preservation experiments, the film effectively delayed spoilage, reduced weight loss, and provided a visual freshness indication. SA-based films reinforced with RCOPI/XG-LEO Pickering emulsions demonstrate considerable potential for multifunctional, biodegradable intelligent food packaging.