Green Synthesized Selenium Nanoparticles Enhance Postharvest Nutritional Quality and Anti-Browning Capacity of Pleurotus ostreatus (Oyster Mushroom).

This study synthesized selenium nanoparticles (SeNPs) using the leaf extract of Cinnamomum longepaniculatum. The extract composition was identified by GC-MS, and the nanoparticles were characterized by UV-vis, SEM, EDX, and FTIR. Three pre-harvest spray treatments of SeNPs at concentrations of 2.5, 5, and 10 mg/L were applied, with water as the control, to investigate their effects on the postharvest quality and browning of Pleurotus ostreatus. The results show that the leaf extract contains more than 13 compounds that can act as reducing and stabilizing agents. The synthesized SeNPs are spherical with an average particle size of 59.32 nm, a polydispersity index of 0.1029, and a ζ-potential of -23.65 mV, and their surface is coated with an organic layer containing carbon and oxygen. Pre-harvest spraying of SeNPs improves the postharvest quality of oyster mushrooms, with the 5 mg/L treatment showing the optimal effect. After 15 days of storage, this treatment group exhibits significantly higher contents of total sugar, soluble protein, total phenols, flavonoids, and ascorbic acid compared to the control. It also maintains higher mushroom lightness (L*), suppresses polyphenol oxidase activity, enhances antioxidant enzyme activity and free radical scavenging capacity, and reduces malondialdehyde content. In summary, pre-harvest spraying of SeNPs effectively improves the postharvest quality and delays browning in P. ostreatus, providing a theoretical and technical basis for oyster mushroom preservation and the high-value utilization of C. longepaniculatum resources.