Comparative study on the characterization of chitosan mixed natural phenolic aldehyde edible films

In this study, the reaction of six natural phenolic aldehydes, namely, ethyl vanillin (EV), syringaldehyde (SA), vanillin (VA), isovanillin (ISA), 2‐hydroxy‐4‐methylbenzaldehyde (HDA), and p‐hydroxy benzaldehyde (PHDA), with chitosan produces Schiff bases of chitosan films. All the complex films were characterized through instrumental analysis. The findings suggested that the degrees of substitution of CS‐EV, CS‐SA, CS‐VA, CS‐ISA, CS‐HDA and CS‐PHDA were 73.48%, 42.22%, 58.04%, 51.52%, 40.89% and 45.23%, respectively. The results of X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT‐IR) analysis confirmed that natural phenolic aldehydes conjugated with chitosan through dynamic imine bonds. The tensile strength and water barrier properties of the films were significantly better than those of the chitosan film. Film thermal stability was altered as a result of the grafting of natural phenolic aldehydes on chitosan. According to the ABTS and DPPH data, the blended films showed better antioxidant packaging performance.