Nanocomposite coating based on nitrogen-doped carbon dots in extending shelf life of fresh-cut pears from the perspective of microorganism

Nitrogen-doped quantum carbon dots were prepared based on Ethylenediaminetetra acetic acid disodium salt (EDTA-Na2) and citric acid, characterized for their structures and properties, and blended with chitosan to make nanocomposite coating film applied in the preservation of fresh-cut pears. The results showed that the PER-CDs (Pleurotus eryngii by-products carbon quantum dots), EDTANa2-doped PER carbon quantum dots (EPER-CDs), EDTANa2 and citric acid doped PER carbon quantum dots (E/NPER-CDs) prepared by hydrothermal method successfully introduced N–H groups on the surfaces, and the doped carbon dots showed good antibacterial on Escherichia coli and Staphylococcus aureus and antioxidant properties. At the end of storage (5 d), the total bacterial count of fresh-cut pears coated with CS (chitosan)/2%E/NPER-CDs was 5.59 log CFU/g significantly lower than that of the control group (7.29 log CFU/g). The E/NPER-CDs inhibited the accumulation of reactive oxygen species (ROS), delayed degradation of total phenol, ascorbic acid and glutathione, as well as significantly reduced the activities of superoxide dismutase (SOD), catalase (CAT), polyphenol oxidase (POD), peroxidase (PPO), and ascorbic acid oxidase (APX) to achieve the effect of enhancing the quality of fresh-cut pears during storage.