Effect of various natural cross-linking agents on the properties of corn starch/soy protein isolate composite films

The severe environmental problems brought by plastic waste have made biodegradable films a research hotspot. Chemical crosslinking is a practical and efficient way to enhance the performance of polymers. Nevertheless, concerns have been raised regarding the potential safety risks associated with conventional chemical crosslinking agents. To address this issue, three natural crosslinking agents (phytic acid, tannic acid, and genipin) were selected in this research to assess their effects on the performance of corn starch/soy protein isolate films. FTIR spectroscopy, XRD patterns and visual color changes of the films collectively confirmed that all three crosslinking agents successfully interacted with the film matrix. The results indicated that these treatments effectively reinforced the films' mechanical properties, UV-blocking ability, and heat resistance. In addition, tannic acid and genipin also enhanced the surface hydrophobicity and moisture barrier performance. Notably, tannic acid cross-linked film exhibited antioxidant activity, which was not observed in the other two films, highlighting its suitability for application in active food packaging. Overall, this study provides a valuable reference for selecting appropriate natural cross-linking agents in the fabrication of starch/protein-based materials. Moreover, the application prospects of cross-linked films are further expanded.