Crab shell powder was dispersed in a 1 M sodium hydroxide solution at 80◦C for 10 h under vigorous stirring. Once completedthe reaction mixture was cooled down to room temperature, and washed with distilled water using three sediment-decant cycles.Precipitate obtained from the above procedure was treated with2.5 M HCl solution for removal of CaCO3 from the crab shell. Thereaction was carried out for 2 days at room temperature withcontinuous stirring. Once completed, precipitate was washed withdistilled water using three sediment-decant cycles. After washing,sample was again charged with 1 M sodium hydroxide solution andstirred for 2 days at room temperature to remove residual pro-teins completely. Then the pigmented compounds were bleachedusing 3% (v/v) solution of H2O2 maintained at pH of 10.5 ± 0.5 usingsodium acetate, reacting for 20 min at 80◦C.