Fruit Processing Wastes as Sustainable Sources to Produce Multifunctional Carbon Quantum Dots for Application in Active Food Packaging

Carbon quantum dots (CQDs) are the newest members of the carbon-based nanomaterials family. These zero-dimensional carbon nanomaterials have been recently used for various applications ranging from electronics to biomedical science due to their relatively simple synthesis process and excellent functional properties. Besides, their safety, non-toxicity, environmental friendliness, and economics have brought them tremendous acceptance in research and industry. Recently, green synthesis of CQDs using sustainable resources such as biomass has been increasingly explored. Attempts have been made to synthesize CQDs from various renewable resources, such as biowaste from agriculture, forestry, microbial biomass, or food processing industries. Fruit processing waste, including peels, refuse, pomaces, and seeds, is one of the biowastes produced in large quantities by the food processing industry. These fruit wastes are carbon-rich sources and can serve as economic and sustainable raw materials for the synthesis of functional CQDs. Since these wastes are rich in polyphenols, the CQDs synthesized using them comprise various surface functional groups, resulting in excellent functional properties. This review discusses the sustainable production of CQDs exclusively from fruit wastes and their properties. Additionally, further surface functionalization of CQDs aiming at the enhancement of their functional properties was discussed. Finally, ongoing research on using fruit waste-derived CQDs as sustainable multifunctional materials in food packaging was reviewed, while challenges and prospects in this research field were highlighted.