Evaluation the effect of Chitosan-Coated Melatonin Nanocomposites on Postharvest Quality of Persimmons in Cold Storage Conditions

Persimmon (Diospyros kaki Thunb) is one of the semi-tropical perishable fruits with a short shelf life, because the softening of the texture, change in chemical compositions and browning in it is faster, which leads to more waste of the product in the postharvest period. Enhancing its shelf life and maintaining quality through the use of edible coatings and natural preservatives is essential. In this study, we evaluated the effects of various treatments on the postharvest quality of persimmon fruit (Karaj variety) during cold storage. The treatments included 0.2% chitosan, 100 μM melatonin, 0.2% chitosan-coated melatonin nanocomposites, and a control (distilled water). The study was conducted in a factorial experiment basd on completely random design with three replications for each treatment and storage duration (15, 30, 45 days). Parameters such as weight loss percentage, soluble solids content, titratable acidity, flavor index, malondialdehyde accumulation, hydrogen peroxide content, total antioxidant capacity, and the activity of antioxidant enzymes (catalase, superoxide dismutase, and ascorbate) were evaluated. The results indicated that fruits treated with chitosan-coated melatonin nanocomposites exhibited significantly less weight loss compared to the control at the end of storage time. The accumulation of malondialdehyde and hydrogen peroxide in this treatment decreased due to the improvement of the antioxidant capacity compared to the control and the activity of antioxidant enzymes (catalase, superoxide desmutase and ascorbate peroxidase) increased compared to the control. Peroxidase activity in treated fruits with melatonin nanocomposite coated with 0.2% chitosan was lower than the control, which .