Development of Eco-Friendly Chitosan Films Enhanced with Bioactive Citric Acid-Based Deep Eutectic Agents for Sustainable Food Packaging and Fish Preservation

This study explores the development of chitosan (CS) films enhanced with citric acid-based deep eutectic agents (CA-DEA) to address the dual challenges of sustainable food packaging and effective fish preservation. CA-DEA was synthesized using citric acid (CA) and choline chloride (ChCl) in molar ratios of 1:1, 2:1, 3:1, and 4:1, with the synthesis confirmed through FTIR analysis. Among these, the 4:1 molar ratio, identified as the most effective formulation for its superior antibacterial properties against E. coli (17.3 ± 0.78 mm) and S. aureus (23.625 ± 0.09 mm), was further evaluated at varying concentrations (0.5%, 1%, 1.5%, and 2%) to examine its effects on the structure and functional properties of CS films. Mechanical testing revealed that films with 0.5% CA-DEA achieved the highest tensile strength (TS; 47.98 ± 2.40 MPa), while higher concentrations led to decreased TS (13.59 ± 1.37 MPa), likely due to over-plasticization. The incorporation of CA-DEA enhanced the films' antibacterial, antioxidant, and UV-barrier properties, significantly improving their bioactivity. As a bioactive coating on tilapia fillets, the incorporation of CA-DEA formulation effectively reduced water loss, preserved protein, controlled TVB-N levels, and extended shelf life, showing the most effective preservation results. This study highlights CA-DEA’s multifunctionality as a bioactive plasticizer, offering a sustainable alternative to conventional packaging and advancing eco-friendly preservation technologies for perishable aquatic products.