Developing silk sericin-based and carbon dots reinforced bio-nanocomposite films and potential application to litchi fruit

Designing cost-effective and sustainable edible packaging films featuring multifunctional activities (antimicrobial, antioxidant, UV shielding) is of great interest in the field of food science and engineering. Herein, the films containing various components of silk sericin (SS), chitosan (CS) as well as carbon dots (CDs) were developed and their physicochemical, structural and bioactive properties were also investigated. Compared with the SS-made film alone, the bio-nanocomposite films (made up of SS, CS, as well as CDs) showed the enhanced flexibility, antimicrobial and antioxidant properties. Moreover, a good compatibility was present among these components, which were well dispersed in the film matrix network. Importantly, due to the existence of CDs, the bio-nanocomposite films indicated a blue fluorescent emission property, which could be used as an anti-counterfeit label. Lastly, the fruit-litchi was selected to verify the fresh-keeping effect of the bio-nanocomposite film, which is effective to reduce the loss of nutritional components, such as water, soluble solids, ascorbic acid, etc. The study can shed light on the use of SS as matrix and CDs as functional ingredient for facile and environmentally friendly preparation of the edible food packaging film as well as for its utilization in food preservation to treat fruits effectively.