Chitosan film loaded with carbon dots and geraniol/hydroxypropyl-β-cyclodextrin inclusion complex: Simultaneous freshness preservation and quality monitoring of pork

Multi-functional film materials that enable monitoring and control of food safety are effective tools for addressing food safety issues. In this study, nitrogen-doped citric acid carbon dot (NCD) functionalized with surface potassium ions was incorporated into chitosan film to confer film pH-monitoring capability. The inclusion complex (HPCDGer) of hydroxypropyl cyclodextrin (HPCD) and geraniol (Ger) was prepared and added as antimicrobial material to the chitosan film. With the increase in pH, the fluorescence intensity of the composite film increased significantly. CS/NCD@HPCDGer exhibited excellent UV shielding, water vapor barrier, antioxidant (Scavenging activity of DPPH and ABTS were 74.01% and 92.48%, respectively), and antimicrobial effects. The inhibition rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 99.82% and 95.89%, respectively. The pH, weight loss, and total volatile alkaline nitrogen (TVB-N) of the pork packed in the composite film were significantly lower. Furthermore, the composite film is capable of showing orange fluorescence in response to biogenic amines from pork spoilage. These results indicate that the composite film has potential applications in the monitoring and control of food safety.