Functional edible coating based on carbon dots and gelatin/cellulose nanofibers for fresh egg preservation

Abstract

A nanocomposite formulation based on cellulose nanofibers (CNF)/gelatin(G) blend was developed and added with various concentrations of nitrogen-functionalized carbon dots (NCD) to use as antibacterial coatings for shell eggs. The physicochemical and functional properties of the films were analyzed, and it was found that NCD enhanced the flexibility of the nanocomposite films by forming strong hydrogen bonds due to the surface functional groups. Although the addition of NCD decreased the water vapor barrier properties, the UV-blocking ability of the films was significantly enhanced, achieving more than 90 % UV-blocking effect with minimal effect on film transparency. The nanocomposite films C/G/NCD (Cellulose Nanofibers/Gelatin/NCD) were loaded with different percentages of NCD such as 1,2,3 and 5 %. Among them C/G/NCD^5 % exhibited strong antibacterial and antioxidant activities, eradicating 100 % of Staphylococcus aureus and Salmonella enterica within 12 h and exhibited excellent free radical scavenging properties. When coated on raw eggs, the C/G/NCD^5 % formulation effectively prevented Salmonella contamination and inhibited further bacterial growth during storage. Our results suggest that the NCD-enhanced CNF/gelatin nanocomposite coating has significant potential as an antimicrobial agent, providing a promising solution for extending the shelf life of eggs and reducing the risk of Salmonella contamination during storage.