Catechin-rich reddish-brown dye from cocoa (Theobroma cacao L) leaf for functionalizing herbal-anchored wool fabrics

Colorists are seriously worried about the long extraction time, low color yield and colorfastness of natural dye obtained via conventional extraction techniques. In this study, microwave (MW)-aided extraction technique was exploited as an alternative method to the conventional extraction technique. The cocoa leaf extraction parameters were varied for obtaining optimal extraction conditions. Likewise, dyeing and mordanting parameters were varied for achieving dyed wool fabric with preferred tint strength (K/S) and colorfastness. The colorimetric properties of MW-aided cocoa leaf extract (CL) dyed wool fabrics were compared to those of the conventional extract dyed fabrics. The antioxidant, antibiotic and ultraviolet protection properties (UPP) of un-dyed, MWirradiated CL dyed and mordanted wool fabrics were evaluated for healthcare functional properties. MWirradiation enhanced the dye yield by 33.82%, reduced the extraction time by 90% and increased tint yield by 44%. The optimal dyeing conditions were liquor ratio 1:20, pH 6, 45 min dyeing time and temperature of 65 degrees C. Post-mordanting with 5% Fe2+ and 9% Al3+ as chemical-mordants enhanced K/S and colorfastness of the dyed fabric from good to very good, while 3% neem and 7% moringa bark extract as herbal-anchors improved the dyed fabrics' K/S and colorfastness from good to excellent. Dyeing enhanced the poor antioxidant and antibiotic properties of MW-irradiated fabrics to excellent, which was further boosted after mordanting process. All the fabrics possess desired UPP. Desired healthcare functional properties of MW-assisted CL dyed wool fabrics after fifth laundry cycle established CL extract as a potential future sustainable colorant for producing healthcare wears.

Automated summary

This study explored the use of microwave-aided extraction technique as an alternative to conventional extraction techniques in order to address the issues of long extraction time, low color yield, and colorfastness associated with natural dyes. The extraction parameters for cocoa leaf were optimized and the dyeing conditions for achieving desired color strength and colorfastness on wool fabric were varied. The colorimetric properties of the microwave-aided cocoa leaf extract dyed wool fabrics were compared to those of conventionally dyed fabrics. The use of microwave irradiation increased dye yield, reduced extraction time, and improved tint yield. The optimal dyeing conditions were determined, and post-mordanting with chemical-mordants and herbal-anchors further enhanced the color strength and colorfastness of the dyed fabric. The dyed fabrics also exhibited improved antioxidant, antibiotic, and ultraviolet protection properties, making them suitable for healthcare applications. The findings suggest that microwave-assisted cocoa leaf extract has the potential to be a sustainable colorant for producing healthcare wears.