The role of organic acid structures in changes of physicochemical and antioxidant properties of crosslinked chitosan films

Traditional chitosan-acetic film, with unpleasant flavor and poor water resistance, is limited in its application in food industry. This study aimed to explore a potential alternative to improve physicochemical properties of chitosan film. Five kinds of cross-linked chitosan films incorporated succinic, adipic, tartaric, malic and citric acid, were obtained by amidation and Maillard reactions. Compared with chitosan-acetic film, cross-linked films improved their thermal stability, swelling degree, water vapor transmission rate and light barrier, attributed to the formation of amide linkage confirmed by FTIR and XPS. Results showed that hydroxylated acid films were more elastic than non-hydroxylated films. Moreover, hydroxylated acid in film prominently decreased the swelling degree, and the lowest value (10.92 +/- 0.75%) was observed in chitosan-malic film. Meanwhile, there was the highest DPPH scavenging rate of 52.19 +/- 3.90% in chitosan-adipic film. Consequently, the crosslinked chitosan film with application-satisfied physical properties has a promising potential for food packaging.

Automated summary

This study aimed to improve the physicochemical properties of traditional chitosan film by cross-linking reactions. The cross-linked films showed improved thermal stability, swelling degree, water vapor transmission rate, and light barrier compared to the acetic film. The hydroxylated acid in the film increased its elasticity and decreased the swelling degree. Therefore, cross-linked chitosan film has great potential for application in food packaging.