Author(s): Sudha, Charu Gupta and Sunita Aggarwal

Abstract:
Microbial colorants are gaining popularity in almost all the industrial sectors viz. Food, textile, paper, agriculture, pharmaceutical, and cosmetics. As compared to synthetic and natural dyeing, this technology is more commercial, reliable, scalable, predictable, and manageable. Leather dyeing industry is also seeking novel ways of green processing. As a solution, in this study, a microbial colorant namely Penicillium minioluteum producing maximum color under optimized conditions (medium-sabouraud; pH-5.6; temperature-15 °C; time-20 days; incubation-static) was used for dyeing wet blue goat nappa skin leather. Leather dyeing conditions were standardized (pH-2.0 altered after 30 min of dyeing, temperature-80 °C and time- 60 min) on the basis of highest color depth and percentage dye exhaustion. Dyed samples showed good rub fastness with moderate to remarkable fading to light and perspiration with no change in tear and tensile strength. The issue of poor light fastness was dealt with tannic acid and vitamin E-gum acacia emulsion. After treatment, improvement in light, perspiration, and rub fastness; tear and tensile strength; and color depth was noted. Darkening of color from red to brown was greatly appreciated as black and brown are popular leather colors. Additionally, a patch sensitivity test of dyed sample exhibited no allergy on human skin.