Carboxymethyl chitosan perilla essential oil Schiff base as promising antibacterial agent: preparation, characterization, and activity

To develop novel antibacterial agents, chitosan (CS) was converted into O -carboxymethyl chitosan (O-CMC), which was then reacted with perillaldehyde and perilla essential oil to synthesize Schiff base derivatives (P-CCSB and PEO-CCSB). Comprehensive characterization via FTIR, 1 H NMR, SEM, EA, XRD, DSC, TGA, and XPS verified the successful synthesis and structural features of these compounds. The derived carboxymethyl chitosan Schiff base (CCSB) exhibited superior antibacterial performance compared to CS and O-CMC, attributable to its reactive Schiff base moiety, nanoscale particle size, elevated cationic charge density, and improved water solubility. After 10 days of storage of large yellow croaker, the total volatile basic nitrogen (TVB-N) and total viable count (TVC) values of the PEO-CCSB group decreased by 10.30 mg/100 g and 1.31 lg (CFU/g), respectively, compared with those of the blank group. These results highlight PEO-CCSB as a promising antimicrobial coating for food preservation.