A Review of the Dye Extraction Methods from the Indigo and Woad Plant

Nowadays, despite the presence of synthetic dyes, due to the environmental damage caused by these substances, the approach of returning to natural sources has been revived. Meanwhile, the indigo plant is one of the best plant sources to achieve blue color. Much research has been conducted to extract dyes from indigo and woad since long ago. The purpose of this research is to collect the studies done in this field and, secondly, to use the results of previous research by researchers to improve the extraction methods. The results of the research showed that several methods, such as traditional, hot water, microbial, enzyme, microwave, etc., could be applied. It was also found that variables such as oxidation speed, oxidation time, alkaline environment of fermentation, type of alkaline material, resting time of fermentation, etc. influence the extraction process of indigo and woad dyes, the effect of pH is much important.</em>.</em>