Development and application of intelligent packaging films based on carboxymethyl starch/PVA with Cu-LTE nanocrystal as functional compatibilizer

In the realm of food safety, innovative intelligent packaging material that can provide the capacity for timely and effectively monitoring the food freshness are essential. In this work, ammonia-sensitive Cu-based metal organic framework (Cu-LTE) nanocrystal was manufactured and characterized, and then explored as a functional compatibilizer of carboxymethyl starch/polyvinyl alcohol (CMS/PVA) blend to develop novel intelligent packaging film materials. The results demonstrated that the introduction of Cu-LTE nanocrystal into CMS/PVA blend brought about significant promotions regarding to the compatibility, mechanical strength (48.1 MPa), UV-protection (with UV transmittance of only 1.6 %), and moisture/oxygen barrier effectiveness, while preserving long-term colour stability of the blend film. Moreover, the developed CMS/PVA/Cu-LTE blend film featured remarkable antibacterial capacity (over 99.0 %) toward both E. coli and S. aureus bacteria, as well as outstanding colour change ability under ammonia environment. The developed CMS/PVA/Cu-LTE blend film also presented visually identifiable colour change during the monitoring of shrimp deterioration. These findings indicated that the developed CMS/PVA/Cu-LTE blend film should hold tremendous potential as an intelligent active packaging material.