Physicochemical and functional properties of chitosans prepared from shells of crabs harvested in three different years

Selected physicochemical and functional properties of chitosans prepared from shells (designated S-04, S-05, and S-07, respectively) of crabs harvested in three different years (2004, 2005, and 2007) were evaluated. S-07 contained higher protein (27.39%) and chitin (20.62%) but lower ash (49.47%) contents compared with those from S-04 (22.42%, 17.35%, and 51.07%) and S-05 (24.94%, 18.20%, and 51.67%). Physicochemical characteristics of chitosans somewhat differed depending on the harvest year of crabs. Degree of deacetylation (89.01%) of chitosan from S-04 was higher than that from S-05 (84.11%) and S-07 (82.49%). Chitosan from S-04 had comparable L∗ (76.41) but lower a∗ (−0.16) and b∗ (13.70) values than chitosans from S-05 (76.94, −0.04, and 15.66) and S-07 (74.92, 0.26, and 14.45). The highest water- (555%) and dye-binding (65.5%) capacities and DPPH radical scavenging activity (18.1%) were observed with chitosan from S-04, having the lowest viscosity (200 mPa s) and the highest degree of deacetylation.