Extraction and characterization of alpha-chitin and chitosan from six different aquatic invertebrates

Chitin and chitosan were extracted from six different aquatic invertebrate species. Species dry weights varied between 5 % and 20 % chitin, and the chitosan productivity of these chitins varied between 66 % and 74 %. Chitin and chitosan structures were characterized by FTIR, TGA, XRD, and SEM. FTIR results showed that the chitins obtained from the organisms were observed in alpha form. Chitin thermal stabilities were in the order Ranatra linearis > Anax imperator > Hydrophilus piceus > Notonecta glauca > Agabus bipustulatus > Asellus aquaticus, and chitosan thermal stabilities in the order N. glauca > A. bipustulatus > A. imperator > R. linearis > H. piceus > A. aquaticus. The crystalline index values of chitins varied between 76.4 % and 90.6 %. Their surface morphology was examined by SEM, revealing nanofibre structures. These six aquatic invertebrate species with characterized chitin and chitosan structures may be used as alternative chitin and chitosan sources for various technological purposes.