Tangerine peel-derived nitrogen-doped carbon dots incorporated chitosan/pullulan-based active packaging film for bread packaging

Citrus peel waste carbon dots based on nitrogen-doped (N-TanCD) were developed by a hydrothermal strategy to deliver active packaging fillers and characterized by transmission electron microscopy, photoluminescence, and Fourier transform infrared analyses. The addition of N-TanCD into chitosan-pululan (CS/Pul@N-TanCD) polymer blend amplified the tensile strength of the composite film by 22.8 %, whereas the antioxidant activities against DPPH and ABTS reached 62.7 % and 91.6 %, respectively. The proposed film showed blocked 98.8 % of UV-A and 100 % of UV-B without affecting the film's transparency. The CS/Pul@N-TanCD film lowered the contamination of L. monocytogenes and E. coli by more than 4 and 5 log CFU/mL, respectively. Sliced bread was packaged using CS/Pul-based films and stored for 12 days at 50 % relative humidity and 25 °C to investigate changes in the quality of the bread. It was found that bread packaged with CS/Pul film integrated with N-TanCD maintained excellent bread quality relating to appearance, moisture content, hardness, weight loss, and total viable bacterial count.