Egg-yolk-derived carbon dots@albumin bio-nanocomposite as multifunctional coating and its application in quality maintenance of fresh litchi fruit during storage

•Carbon dots (CDs) with fluorescent and antioxidant properties were synthesized.•Chitosan enhances the coating’s antibacterial and mechanical properties.•Multifunctional coating was prepared with egg albumin, chitosan and CDs.•The composite coatings exhibited UV blocking and strong antioxidant activity.•Albumin bio-nanocomposite coating reduced postharvest losses of fresh litchi fruit. Green synthesis of a bio-nanocomposite coating containing egg albumin, chitosan, and carbon dots (CDs) was achieved. Physical, chemical and biological properties of the coating and its application in quality maintenance of litchi were explored. The results demonstrated that the coating prepared with egg albumin, chitosan and CDs in a volume ratio of 5:5:1 had good flexibility, antibacterial, antioxidant and UV barrier properties. Compared to control litchi, during storage, the litchi coated with bio-nanocomposite displayed a lower pericarp browning index, a lower percentage of weight loss, and a lower content of reducing sugar, but retained high contents of vitamin C, total sugar, and sucrose, higher levels of chromaticity a∗, b∗, and L∗ values. These results indicated that the novel multifunctional bio-nanocomposite coating based on egg albumin, chitosan, and CDs could be a safe and eco-friendly method to maintain the quality and reduce postharvest losses of fresh litchi during storage.