Valorization of carbon dots from cashew (Anacardium occidentale) and jik (Barringtonia acutangula) leaves: Multifunctional preservatives for extending shelf life of precooked baby clam meat

Transforming agro-waste into carbon dots (CDs) enables sustainable biomass valorization while producing versatile nanomaterials for applications in packaging and food safety. CDs were synthesized using an eco-friendly hydrothermal method from Thai indigenous leaves including cashew (C-CDs), jik (J-CDs) and the combined CDs (CJ-CDs), and all CDs were characterized. The resulting CDs yielded nanoscale particle (2.18-2.50 nm) and had remarkable UV-blocking properties. All CDs displayed strong antimicrobial activity against common foodborne bacteria and fungi. Furthermore, CDs had superior radical scavenging activities, in which CJ-CDs exhibited the highest overall antioxidant potential. Notably, CJ-CDs showed enhanced functional performance, suggesting a synergistic effect arising from the combined phytochemical precursors, which likely promoted improved surface functionality and radical scavenging efficiency. When CJ-CDs were investigated for their potential in preserving precooked baby clam meat (PBCM), treatment with CJ-CDs effectively reduced pH changes, microbial growth and lipid oxidation of PBCM during the refrigerated storage for 12 days. Control sample exceeded the acceptable microbial limit of 6 log CFU/g on day 6, whereas CJ-CD-treated samples (PBCM-CJ-CDs) maintained microbial counts below this limit on day 9, demonstrating a shelf-life extension of longer than 3 days. Overall, the findings indicated that CJ-CDs function as multifunctional natural preservatives with synergistically enhanced antioxidant and antimicrobial properties, offering a sustainable and green alternative to synthetic additives for extending the shelf life of seafood products. • CDs were synthesized from cashew and Jik leaves as C-CDs, J-CDs and combined CJ-CDs • CJ-CDs exhibited superior UV-blocking abilities against UV-A and UV-B lights • C-CDs and CJ-CDs had higher antioxidant and antimicrobial activities than J-CDs • CJ-CDs had high preservation effect on refrigerated precooked baby clam meat (PBCM) • All CDs prevented lipid oxidation and microbial growth in refrigerated PBCM