Biomimetic Synthesis of Silver Nanoparticles for Preparing Preservative Solutions for Mandarins (Citrus DeliciosaTenore)

Mandarin (Citrus deliciosa Tenore) is one of the most important fruit crops grown in the Hue province, Vietnam, and has immense economic, health and cultural significance. However, mandarins are highly perishable and more susceptible to diseases compared to other citrus fruits. In the present study, biomimetic synthesis of silver nanoparticles (AgNPs) for preparing preservative solutions for mandarins was investigated. Spherical and nanometer-sized AgNPs that were prepared with the help of ultrasound wave induced a reaction between silver nitrate solution (AgNO30.02[Formula: see text]M) and the leaf extract of Centella asiatica. Spherical AgNPs were formed easily in the extract at an ambient temperature and their average size ranged from 3[Formula: see text]nm to 30[Formula: see text]nm. These AgNPs exhibited potent antifungal activity against Macrophoma theicola B1 fungi, which were isolated from mandarin peels collected from agricultural lands of rural villages of Thua Thien-Hue province in Vietnam. Thus, we are successful in preparing an AgNPs-containing preservative solution as a mandarin fruit-coating material to inhibit the growth of M. theicola B1 fungi. The coating of mandarin fruits with this preservative solution prolonged the storage life of the fruits from 9 to 35 days. On the 35th day, the preserved fruits maintained their natural color and ripening, whereas the control sample decayed with white fungus covering its skin after 9 days of storage. Thus, coating mandarins with this solution can be proposed as an additional treatment for increasing their postharvest quality. Additionally, it can be a solution for protection against fungal infection and physiological damage and controlling the decay of mandarins, thereby prolonging their shelf life.