Development of cinnamaldehyde/aminated gelatin film as pH-responsive controlled-release packaging for cherry preservation: Effects of CO2 and humidity in the microenvironment

Abstract

pH-responsive materials control the release of active substances by responding to pH changes in the environment. In this study, based on the properties of imine bond with acid-sensitive hydrolysis and mild reaction conditions, cinnamaldehyde was immobilized onto aminated gelatin (AGel) films to generate cinnamaldehyde/aminated gelatin (Cin/AGel) films, which were then applied to preserve cherries. FTIR and XPS confirmed the synthesis of imine bonds. The excellent pH-responsive controlled-release properties of Cin/AGel films were demonstrated by monitoring changes in the cumulative release fraction of cinnamaldehyde in the aqueous phase (different pH buffers) and in atmospheric environments (different CO₂ concentrations and humidity). Even when not in direct contact with the aqueous phase, it can nevertheless provide effective regulated release to the acidified environment caused by CO₂ accumulation and high humidity conditions. Furthermore, the Cin/AGel films had smart antibacterial properties. Compared to PE and AGel films, Cin/AGel film packaging increased the shelf life of cherries by 9 and 6 days at 4 °C, respectively. As a result, the shown pH-responsive controlled-release films have promising applications in controlling the release of antimicrobial agents during food preservation.