Synergistic Antimicrobial Effects of Citric Acid-Based Deep Eutectic Bioactive Agents in Chitosan Coatings for...

Penaeuschinensis is an economically important seafood species valued for its nutritional quality and global market demand. However, its high perishability makes it highly susceptible to rapid quality deterioration during refrigerated storage, primarily due to microbial proliferation, enzymatic activity, and oxidative reactions. To address these challenges, this study proposes a sustainable chitosan-based coating incorporating a citric acid-choline chloride deep eutectic agent (CA-DEA) as an innovative preservation strategy for shrimp. The composite coating demonstrated markedly enhanced antioxidant and antibacterial activities compared to CTS or CA-DEA alone. The CTS-CA-DEA coating effectively preserved shrimp quality over 8 days of refrigerated storage, as evidenced by reduced discoloration, moisture loss, and textural degradation during storage. These quality improvements were accompanied by greater stability of key biochemical indicators, including peroxide value, pH, total volatile basic nitrogen, and protein content, indicating a slower progression of spoilage reactions. Electronic nose analysis further revealed a reduced generation of lipid- and protein-derived volatile compounds associated with shrimp deterioration, consistent with the observed physicochemical changes. Based on the accepted TVB-N acceptability threshold (30-35 mg/100 g), the CTS-CA-DEA treatment prolonged the estimated acceptable refrigerated storage period to approximately 7 days, compared with only about 4 days for the uncoated control, clearly demonstrating the beneficial effect of the composite antimicrobial coating. Collectively, these results demonstrate that the CTS-CA-DEA coating is an eco-friendly preservation strategy that integrates barrier protection, antimicrobial activity, and antioxidant defense, thereby extending refrigerated shelf life while maintaining shrimp quality.