Preparation of a Double-Layered Composite Film Loaded with Cinnamic Acid@Mesoporous Silica and Its Application in Blueberry Preservation

This study developed a double-layered active packaging film based on chitosan and zein loaded with cinnamic acid@mesoporous silica and nano-silica. The film was composed of a hydrophobic zein outer layer that acted as a moisture barrier, and a hydrophilic chitosan inner layer that provided moisture retention. Cinnamic acid was encapsulated within mesoporous silica. The resulting composite (cinnamic acid@mesoporous silica) demonstrated excellent safety, stability, and antibacterial efficacy. The effects of cinnamic acid@mesoporous silica and nano-silica on physical properties of the film were investigated, and the effect of the film on blueberry preservation was evaluated. The results indicated that both components improved the interfacial compatibility of the film materials by forming a denser structure within the film-forming matrix, thereby significantly improving the overall performance of the films. The optimal film performance was obtained by adding 2.5% cinnamic acid@mesoporous silica, as evidenced by markedly improved mechanical strength, thermal stability, and ultraviolet barrier property, as well as enhanced barrier properties against water vapor, oxygen, and carbon dioxide. This film effectively reduced the decay rate and mass loss of blueberries, extending the shelf life to 8 days. It also minimized changes in firmness, total soluble solids, and titratable acidity. These findings indicate the promising potential of the film for commercial application in postharvest fruit preservation.