Raw crab shells (Portunus pelagicus) were thoroughly washedand separated according to their size. Crab shells having carapace length of only 14 ± 1 cm was selected for the experiments sincethis length usually corresponds to the fully grown species. Reagent
grade sodium hydroxide, hydrochloric acid, sodium acetate, Hydro-gen peroxide and acetic acid were obtained from Sigma Aldrich(USA). Chitosan flakes were obtained from HiMedia laboratories(India) having a purity level of 99% and degree of deacetylation higher than 85%. Distilled water was used in all the experiments.