Effect of drying and harvest time on the physicochemical properties of the most common Korean persimmon leaves

Persimmon is a plant that is native to the Republic of Korea. It leaves are rich in antioxidants and minerals. This study set out to investigate the moisture, color, vitamin C, and mineral contents of five of the most common Korean persimmon leaves ('Sangju-dungsi', 'Sangam-dungsi', 'Cheongdobansi', 'Gabjubaekmok,' and 'Suhong'), and how they varied with the applied drying technique (freeze-drying or hot-air drying at 100°C for 30 min) and harvesting time (late May or late June). Persimmon leaves were first collected, and then blanched and dried. Our results revealed that freeze-drying was the most effective method in terms of the mineral content, while no significant difference in the vitamin C content was observed regardless of the drying method. The concentration of Mg, Ca, K, and Mn increased from May to June, while the opposite trend was observed for Na, Fe, Cu, and Zn. Persimmon leaves collected in late May had a higher vitamin C content than those harvested in late June. Ultimately, the 'Sangam-dungsi' persimmon leaf was found to have the highest mineral content, whereas 'Gabjubaekmok' leaves were richer in color (lightness, redness, and yellowness) and had the highest vitamin C content among the analyzed cultivars.