The aim of this study is to investigate the efficacy of persimmon (Diospyros kaki L.) peel extract as a reductant for indigo dyeing. Dried persimmon peel was water extracted and its sugar contents and functionalities were determined. Its reducing power was studied in terms of redox potential of the indigo bath and color strength (K/S value) of the ramie fabrics dyed in the indigo reduction bath. Total sugar content of the extract was 74.3%. Antioxidant capacity reached up to 86.0% at 3.5 μg/mL of the extract concentration. The persimmon peel extract had an effect on indigo reduction and the maximum color strength was obtained within one or two day. At 2–3% of the extract concentration, the redox potential of the indigo bath was maintained in the range of − 550 ~ − 600 mV for 10 days. With increase in the extract concentration, reduction state lasted for longer time and higher color strength was obtained. The persimmon peel extract can be used for indigo reduction dyeing as a sustainable, nontoxic, biodegradable alternative to sodium dithionite.

中文翻译：

---

柿子的应用（柿L.）在靛蓝染色果皮提取物作为环保替代还原剂

本研究的目的是研究柿子（Diospyros kaki L.）果皮提取物作为靛蓝染色还原剂的功效。将柿饼皮干燥后进行水提取，并测定其糖含量和功能性。根据靛蓝浴的氧化还原电势和在靛蓝还原浴中染色的the麻织物的色强度（K / S值）研究了其还原能力。提取物的总糖含量为74.3％。在提取物浓度为3.5μg/ mL时，抗氧化能力达到86.0％。柿皮提取物具有减少靛蓝的作用，并且在一到两天内获得了最大的色强度。在浸提液浓度的2-3％时，靛蓝浴的氧化还原电势保持在-550〜-600 mV的范围内10天。随着提取物浓度的增加，还原状态持续更长的时间并获得更高的色强度。柿皮提取物可用于靛蓝还原染色，作为连二亚硫酸钠的可持续，无毒，可生物降解的替代品。