Aldehyde-dependent β-aminocarbonyl chitosan/Ag composites: Linking chemical structure, silver loading, and antibacterial performance

In this study, β-aminocarbonyl chitosan (BACC) derivatives were synthesized through Mannich modification using different aldehyde precursors and subsequently incorporated with Ag to investigate the relationship between chemical structure, Ag loading, and antibacterial performance. The resulting materials were characterized by FTIR and UV-Vis spectroscopy, while Ag incorporation was quantitatively determined using atomic absorption spectroscopy (AAS). Antibacterial activity was evaluated against bacteria associated with fresh chicken meat using the total plate count (TPC) method at concentrations of 1000 and 2500 ppm after 0, 3, and 7 days of refrigerated storage. FTIR analysis indicated interactions of Ag species with nitrogen- and oxygen-containing functional groups, while the evolution of surface plasmon resonance bands supported the formation and stabilization of Ag species. AAS revealed structure-dependent Ag loading, with values of 1.25%, 0.93%, 0.80%, 0.73%, and 0.53% for BACC-Sa/Ag, BACC-OV/Ag, BACC-F/Ag, Ch/Ag, and BACC-P/Ag, respectively. BACC-Sa/Ag achieved the highest bacterial reduction of 96.39 ± 0.39% at 2500 ppm after 7 days, while BACC-F/Ag reached 96.27 ± 0.59% under the same conditions. Notably, BACC-P/Ag achieved 95.40 ± 0.42% reduction after 3 days at 1000 ppm despite having the lowest Ag loading. These results demonstrate that antibacterial performance was governed by the combined effects of aldehyde-derived functionality, Ag incorporation, concentration, and storage time rather than Ag loading alone. The results demonstrated their potential to suppress microbial growth, highlighting the applicability of these materials as candidates for further development in antibacterial food-preservation systems. Nevertheless, additional investigations involving film fabrication, silver-ion release, migration, and safety assessments are necessary before their suitability for food-contact packaging applications can be established.