Application of Chitosan/CMC Composite Films for Improving the Safety and Quality of Chilled <i>Litopenaeus vannamei</i>

Antimicrobial packaging films are widely used to maintain food quality and extend shelf life. This study evaluated the physicochemical and antimicrobial properties of chitosan/carboxymethylcellulose (CMC) composite films and their effectiveness in preserving Litopenaeus vannamei during chilled storage. Chitosan was incorporated at 0%, 1%, 2%, and 4% into CMC films, which were characterized by Fourier transform infrared spectroscopy (FTIR) spectroscopy, revealing maintained structural integrity in all films with -OH/-NH stretching, Amide I and II vibrations, and C-O-C ether linkages indicative of strong hydrogen bonding and polymer interactions. The 1% chitosan/CMC film exhibited optimal physicochemical properties, including low moisture content (22.21% ± 4.33%), controlled thickness (0.12 ± 0.02 mm), reduced water solubility (28.17% ± 8.82%), high elongation at break (466.50% ± 8.50%), comparable tensile strength (0.03 ± 0.01 MPa), low opacity (0.01 ± 0.00), and minimal color difference (0.57 ± 0.06). All films demonstrated antimicrobial activity, with larger inhibition zones against Sphingomonas paucimobilis and Staphylococcus schleiferi. Notably, 4% chitosan/CMC film effectively reduced total bacterial and coliform counts (5.77 ± 0.07 and 3.44 ± 0.42 log₁₀ CFU g^-1, respectively) during storage, maintaining shrimp freshness for up to 15 days. These results indicate that 1% chitosan/CMC films are optimal for physicochemical performance, whereas 4% films are preferred for antimicrobial protection. Future improvements to the 1% formulation could include incorporating nanofillers to enhance microbial control without compromising flexibility or transparency, making it more suitable for active seafood packaging. PRACTICAL APPLICATIONS: This study demonstrates that chitosan/CMC composite films, particularly those with 1% and 4% chitosan, can be used as eco-friendly packaging or coating materials to help maintain shrimp freshness during storage. The films improve physical stability and provide antimicrobial protection, which may help slow bacterial growth and extend product quality in chilled seafood. These findings offer a potential low-cost, biodegradable alternative for seafood processors seeking safer and more sustainable packaging options.