Adansonia digitata L. derived carbon dots as pickering stabilizers for cinnamon oil emulsion coatings with antibacterial and food-preservation properties

Food spoilage caused by microbial contamination remains a major challenge for food safety and shelf-life preservation. In this study, a surfactant-free Pickering emulsion coating stabilized by biomass-derived carbon dots (CDs) synthesized from Adansonia digitata L. petals and combined with cinnamon oil was developed for food preservation. The CDs were synthesized using a hydrothermal method and applied as solid stabilizers to form a CD–cinnamon oil Pickering emulsion (CDs–CO–PE). Structural and morphological analyses confirmed the formation of quasi-spherical CDs with an average particle size of approximately 8 nm and abundant oxygen-containing functional groups that facilitated stabilization of the oil–water interface. RAW 264.7 cells, viability ranged from 95.19% to 109.12%, whereas in Caco-2 cells, it ranged from 98.11% to 102.89%. Antibacterial activity was observed against Escherichia coli and Staphylococcus aureus by CDs–CO–PE, with inhibition-zone diameters of 28 mm and 35 mm, respectively. The CDs–CO–PE showed a higher total phenolic content than CDs alone (1,591.89 ± 11.78 versus 890.43 ± 15.11 mg GAE/g) and stronger radical-scavenging activity, as indicated by lower DPPH IC₅₀ values (189.11 ± 1.67 versus 241.73 ± 0.61 mg/L) and ABTS IC₅₀ values (215.64 ± 0.56 versus 223.31 ± 1.97 mg/L). When applied as apple coating, the CDs–CO–PE reduced moisture loss and delayed browning, maintaining 86.61% weight retention after 7 days compared with 81.12% for untreated apples and 78.44% for apples coated with CDs alone. The emulsion also maintained its physical, chemical, and antibacterial stability during 30 days of storage. The CDs–CO–PE coating effectively preserved apple quality for 15 days by reducing browning, dehydration, and surface deterioration. These findings demonstrate the potential of CDs–CO–PE as a sustainable coating system for extending the shelf life of fresh produce.