Discharge printing on cotton fabric using fruit peel extracts as natural reducing agents

Conventional reducing agents are effective in discharge printing, but concerns about chemical safety, environmental impact, and sustainability have encouraged the quest for greener alternatives. This study aims to evaluate orange and pineapple peel extracts as natural reducing agents for discharge printing on reactive-dyed cotton fabrics and compare their performance with conventional agents (thiourea dioxide, sodium sulfoxylate formaldehyde, and sodium dithionite) in terms of color strength reduction, whiteness index, and bursting strength. Aqueous extracts of orange peels and pineapple peels were prepared by boiling in water and applied via discharge printing on reactive-dyed cotton fabrics. Infrared spectroscopic analysis of the extracts supported the presence of hydroxyl- and carbonyl-associated functional groups consistent with phytochemicals capable of reducing activity, while that of the discharged fabrics indicated noticeable changes in dye-related absorption bands, particularly in the fingerprint region. Comparison with traditional reducing agents showed that both fruit peel extracts effectively discharged the dye. Although performance varied slightly with dye shade, pineapple peel extract achieved the highest reduction (95.60%) in color strength. Conventional discharging agents generally produced higher whiteness responses, but the fruit peel extracts still provided substantial discharge with acceptable optical and mechanical performance. Bursting strength measurements showed moderate loss of strength (14.73% to 21.65%) after printing. Overall, the results demonstrate that orange and pineapple peel extracts can serve as promising natural reducing agents for bio-based discharge printing.