Chitosan–Fucoidan Gel Formation for Food Packaging Film Development Incorporating Blackcurrant Anthocyanins for Monitoring Tuna Freshness

This study investigated the development, fabrication, and characterization of a novel biodegradable food packaging film based on chitosan (CH) and fucoidan (FU), incorporating blackcurrant-derived anthocyanins (BCAs). The system was designed to enable real-time monitoring of tuna (Thunnus spp.) freshness, while addressing environmental concerns through the replacement of synthetic materials with a bioactive, multifunctional alternative that provides both mechanical protection and dynamic spoilage indication. Films were prepared using a casting method with varying BCA concentrations (0.2%, 0.4%, and 0.6%) and systematically evaluated in terms of their structural, physicochemical, and biological properties. The results indicated that the CH/FU/BCA film containing 0.4% BCA exhibited optimal performance, characterized by enhanced tensile strength, reduced water solubility and moisture content, and improved thermal stability and barrier properties. The incorporation of BCA enabled distinct color changes in response to spoilage-related conditions, supporting its function as a pH-responsive indicator. In addition, the films demonstrated significant antimicrobial activity against Escherichia coli and Staphylococcus aureus, affirming their suitability as active packaging materials. Zeta potential analysis further indicated improved colloidal stability upon BCA incorporation. Overall, the synergistic interactions among CH, FU, and BCA resulted in a multifunctional film with combined protective and freshness-indicating capabilities. These findings highlight the potential of the developed biofilm for application in intelligent seafood packaging systems.