Cellulose nanofiber-based active packaging film enhanced with carbon dots and hydrochar derived from nettle

Carbon dots (CD) and hydrochar (HC) derived from nettle were synthesized using a zero-waste synthesis method, and their effectiveness was elucidated as active packaging fillers. Cellulose nanofiber (CNF)-based films were produced by blending CD (CNF/CD) and HC (CNF/HC), resulting in improved preservability of pork sausages. The CNF/CD and CNF/HC films enhanced the UV blocking performance, reducing UV-B transmittance by 91.7% and 83.3% and UV-A transmittance by 85.2% and 58.9%, respectively. The CNF/CD and CNF/HC films strongly inhibited S. enterica, S. aureus, E. coli, and L. monocytogenes, followed by ABTS radical scavenging by 100.0% and 73.2%, respectively. Active packaging studies confirmed that CNF/CD and CNF/HC films prolonged the shelf life of sausages by up to 18 days at 4 °C by delaying lipid oxidation, reducing microbial growth, and maintaining firmness. These findings showed the potential of CD and HC as eco-friendly multifunctional additives in sustainable active packaging for meat preservation.