Azadirachta indica derived copper oxide nanoparticles: A sustainable approach for reducing post-harvest losses and enhancing mango quality

Abstract

In this study, the green synthesis of copper oxide nanoparticles (CuO NPs) mediated by Azadirachta indica is reported, along with an evaluation of their antifungal activity against post-harvest anthracnose and their effects on the storage behaviour (shelf life) and physico-chemical properties of ‘Kesar’ mangoes, particularly those associated with the ripening process. The CuO NPs were initially synthesized using neem leaf extract and characterized through UV- Visible spectroscopy, SEM, EDX, HR-TEM, FT-IR, XRD, XPS, DLS and zeta potential. Characterization confirmed their monoclinic crystalline structure, spherical morphology, high purity, and stability, with a mean size of 50.93 nm and a zeta potential of −32.50 mV. The antifungal activities of synthesized CuO NPs against the fungus Colletotrichum gloeosporioides were assessed using poisoned food technique in which 1000 ppm CuO NPs showed lowest colony diameter (20.70 mm) and highest per cent growth inhibition (77.00 %). Subsequently in a dipping treatment lowest per cent disease incidence (00.00 %) were recorded in fruit treated with CuO NPs @ 200 ppm and 250 ppm, respectively. While, highest shelf life (18.23 days) were recorded in fruit treated with CuO NPs @ 250 ppm. Untreated control fruit exhibited increased percent weight loss, total sugar, reducing sugar, non-reducing sugar and total soluble solids (TSS) over the storage period which responsible for early and rapid ripening. Post-harvest treatments of CuO NPs improved mango quality by reducing weight loss, retaining firmness, and delaying ripening through maintaining peel thickness, lower sugar levels, and higher titratable acidity and ascorbic acid. The 250 ppm concentration was most effective, ensuring safety with copper levels below toxicity thresholds. Therefore, A. indica-CuO NPs treatment is an eco-friendly and safe alternative to preserve fruit quality, reducing post-harvest disease/losses and extending the storage period (shelf life) of mango by delayed the ripening process.