Edible coating of Chrysanthemum morifolium by-products derived carbon quantum dots alleviated postharvest quality deterioration of Gastrodia elata through regulating phenylpropanoid pathway

Gastrodia elata ( G. elata ), a traditional medicinal and edible plant, is susceptible to quality deterioration through enzymatic browning and microbial spoilage during storage. Carbon quantum dots (CQDs) derived from Chrysanthemum morifolium leaves (CQDs-Leaf) and stems (CQDs-Stem) combined with sodium alginate and konjac glucomannan as coatings were developed to enhance antioxidant and antifungal activity of coating, extending the shelf life of G. elata . The effects of CQDs on the physicochemical, structural, and functional activity of nanocomposite particles were evaluated. CQDs exhibited strong antioxidant capacity (IC 50 of CQDs-Leaf for ABTS and DPPH radicals were 50.90 μg/mL and 54.45 μg/mL, respectively), and inhibitory effects against dominant spoilage fungi of G. elata ( T. harzianum and F. redolens ). Moreover, CQDs-Leaf in coating with smaller particle size (100–113 nm) and hydroxyl-rich surfaces, reduced weight loss and disease incidence over 40-day storage by enhancing phenylpropanoid enzyme activities and suppressing lipid peroxidation. CQDs-Stem coating inhibited fungal growth via electrostatic adhesion, reducing decay of G. elata . CQDs coatings delayed rot onset by 10–15 days through regulating phenylpropanoid pathway. This study provides a sustainable strategy utilizing biomass-derived nanomaterials for bioactive food preservation, offering significant potential to reduce postharvest losses of perishable medicinal plants while promoting resource-efficient utilization of agricultural byproducts.