A novel multifunctional bioactive film based on Gelidium amausli polysaccharide incorporated with lingonberry anthocyanin for fish freshness monitoring and preservation

This study aimed to develop a sustainable bioactive film with active and intelligent characteristics. Gelidium amansii polysaccharides (PC) were used as the film-forming substrate, lingonberries anthocyanins (VVE) as indicators to create a polysaccharide-based anthocyanin composite film with excellent physicao-mechanical properties. Characterization indicated that VVE was effectively trapped within PC substrate with good compatibility. It had various desirable properties: strong antioxidant activity (DPPH: 85.40 ± 0.1% and ABTS: 95.74 ± 0.1%), potent antibacterial effects against S.aureus and B . subtilis (inhibition zone diameters of 15.97 ± 0.22 mm and 15.03 ± 0.21 mm), and outstanding oxygen barrier performance (oxygen permeability of 658.27 ± 18.73 cm³/(m 2 ·24h·0.1MPa)). Also, the film displayed significant colorimetric responses to pH 3-12 buffers and volatile ammonia. Intelligent assay for fish freshness monitoring showed that the film’s color changes from pink (fresh fish) to brownish purple (spoiled fish) at 4°C. Furthermore, active assay, the bioactive film extended the shelf life up to 14 days (TVB-N 16.25 mg/100g; TVC 6.72 lg cfu/g). The results suggested the film can be used for real-time freshness monitoring, prolonging the shelf life of fish and reducing quality deterioration during storage, highlighting its significant application potential as a multifunctional intelligent active film in the food industry. • Anthocyanin was immobilized in the polysaccharides matrix with good compatibility. • The indicator film can monitor the real-time freshness of fish. • Anthocyanins with antibacterial effects can delay the quality change of fish during storage process. • The intelligent composite film provides a green and feasible way. • Providing a theoretical basis for the field of food quality and safety.