Characterization and anti-Vibrio activity of citral-chitosan Schiff base complexed tannic acid-zinc slow-release bacteriostatic formulations

Natural citral has attracted widespread attention for its antibacterial properties, but its instability during processing and in biological systems, such as the gastrointestinal tract, limits its application as an antibiotic alternative. This study aims to enhance the stability and antibacterial efficacy of citral by formulating it into a sustained-release system using Schiff base reaction and metal complexation with chitosan (CS), tannic acid (TA), and zinc (Zn). Characterization of the CS-CT-TA-Schiff base/OH-TA-Zn (CS-CT-TA-Zn) complex revealed a porous, rough morphology with an average particle size of 366.97 ± 48.02 nm. The composite exhibited a citral loading capacity of 57.78 ± 1.33 %, with pH-responsive sustained release behavior observed within the pH range of 1.5–2.0. Tannic acid's antioxidant properties helped maintain the formulation's stability. Antimicrobial testing showed that the citral loading in the composite at the Minimum Inhibitory Concentration (MIC) against Vibrio parahaemolyticus was 20 μg/mL, effectively disrupting the bacterial cell membrane and inhibiting biofilm formation. The CS-CT-TA-Zn complex significantly enhances the stability and antibacterial activity of citral, providing new insights into its application as an antimicrobial agent targeted for delivery to the human stomach, and increasing its potential as a more effective food additive. • Citral with chitosan and TA-Zn II coordination complex were obtained. • The stability of citral were improved with chitosan and TA-Zn II shells. • The citral complex exhibits dynamic and slow release character for citral. • The citral complex exhibits strong anti-Vibrio effects.