Mao berry as a green reducing agent in natural indigo dyeing on cotton fabrics

In this work, mao berry extract was tested to determine whether it could be a green alternative reducing agent in the indigo dyeing on cotton fabrics. Glucose and fructose, which are the main reducing sugars in the extract, could reduce natural indigo pigment into its water soluble leuco form in the alkaline solution. Sodium hydroxide and calcium hydroxide were compared for their effectiveness in the alkaline reduction of indigo. The reduction potentials of the indigo dyebath using mao berry extract were evaluated with reference to the conventional reducing agent, sodium dithionite (Na2S2O4), and different reducing sugars. The results from colour strength and colour fastness to washing, light and rubbing of the dyed cotton fabrics using the extract were comparable with other reducing agents especially in NaOH. Mao berry extract gave satisfactory results as a green alternative to Na2S2O4 in the natural indigo dyeing process. Moreover, the UV protection ability of the dyed cotton fabrics was enhanced by the natural indigo dyes applied.