Incorporation of carbon dots into polyvinyl alcohol/corn starch based film and its application on shiitake mushroom preservation

Developing eco-friendly edible packaging films with multi-functional properties is highly required. This study involved synthesizing carbon dots (CDs) from dragon fruit, then incorporating them into a composite film based on polyvinyl alcohol (PVA)/corn starch (CS) to create a functional package to extend the shelf life of fresh shiitake mushrooms. Functional composite films with varying levels of CDs were formulated. The films' characteristics of morphology, mechanical properties, antioxidant properties, etc. were then determined, as well as their preservation effect on the fresh shiitake mushrooms. The results showed that the PVA/CS/CDs composite film showed excellent mechanical property, Ultraviolet (UV) barrier capability, antioxidant and antimicrobial properties. Specifically, addition of 8 mg/mL CDs in the composite films reduced weight loss of shiitake mushrooms by 30.74 %, decreased the decline in soluble solids content by 10.48 %, and halved the reduction in total sugar content after a 7-day storage period compared to films without added CDs. Furthermore, the films effectively lowered the respiratory intensity and browning of the mushrooms. This research demonstrates that CDs can serve as an effective component for the development of eco-friendly edible packaging films, as well as for their application in food preservation.