Characterisation of Chitosan from Blowfly Larvae and Some Crustacean Species from Kenyan Marin Waters Prepared Under Different Conditions

Abstract

Abstract—Isolation of chitosan from cuticles of blue bottlefly larvae Calliphora erythrocephala, and shells of crab Sylla cerrata, lobster Panulirus ornatus, prawn Paeneaus indicus was carried out. The yield of chitin was 12.0%, 23.0%, 15.7 % and 28.0 % respectively. In the same order the yield of chitosan was 66.0%, 74.6 % 74.3 % and 75.0 % from chitin. Ash in the crab and lobster chitosan demineralised with 0.5M HCl was 30.2 and 22.4 % respectively. This was reduced to 0.2 % for lobster and 0.4 % for crab using 2M HCl for demineralisation and 0.5M HCL was adequate for demineralisation of prawns to bring the ash content to < 1%. The ash content in the blowfly larvae was negligible. The conditions used for chitosan isolation in blowfly larvae were milder requiring no demineralisation step. The time to obtain soluble chitosan in 1 % v/v acetic acid was 8 hr for crab and lobster at 100°C deacetylation and 4 hr at 120°C while for prawns it was 6 hr at 100°C and 3 hr at 120°C deacetylation temperature. The average molecular weight (¯M V) for crabs was 556,000 after 8 hr deacetylation and 148,000 at 140°C deacetylation temperature. With 2M HCl used for demineralisation first, it was 439,000 for a 4 hr period. Crabs, first demineralised then deprotenised the ¯M