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 (IC₅₀ 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.