4. Conclusions
Cotton fabrics were treated with whey protein isolate to improve their dye ability with tannin-rich dye extracted from the bark of X. granatum. Soy protein isolate was also used for comparison. The dyed fabrics appeared reddish-brown with the deepestshade obtained at pH values around 5. The enhancement in thecolor strength was correlated with an increase in the following:protein concentration, dye concentration, dyeing time and dyeing temperature. The improvement in the dye absorption after protein retreatment is ascribed to insoluble complex formation between tannin and proteins, which relies mainly on hydrogen bonding and hydrophobic interactions. The dyed fabrics show mostly good to excellent color fastness properties; however, the fastness ratings to light and crocking in the wet state varied depending on the color strength. A small deterioration in the tensile and tearing performance was observed in fabrics treated with protein, although treatment resulted in slight increases in the sample stiffness. Both protein treatment and dyeing improved the ultraviolet shielding efficiency of the cotton fabrics.