Properties of chitin and chitosan extracted from silkworm pupae and egg shells.

Chitin and chitosan from silkworm pupae and egg shells show distinct properties with excellent antimicrobial properties and cytocompatiblity. Spent silkworm pupae and hatched egg shells are discarded as waste but contain valuable carbohydrates, proteins and lipids. Chitosan has excellent antimicrobial properties and is widely used for food, medical and biotechnological applications. In this paper, we report the properties of chitin and chitosan from silkworm pupae and egg shells in comparison to commercially available chitosan. Defatted and deproteinated pupae and shells were demineralized and later deacetylated to form chitosan. Thermal behavior, physical structure, antimicrobial activity and ability to support the attachment and growth of NIH3T3 cells were studied. Chitin and chitosan from both pupae and shells had similar structure and composition. Crystallinity of the pupae chitosan was 48% compared to 38% for egg shell chitosan. Silkworm chitosan showed considerably higher antibacterial and antifungal activity compared to standard. Cells were viable in the presence of pupae and egg shell chitosan in all the concentrations tested. Based on these observations, it can be inferred that silkworm pupae and shells provide a renewable and sustainable source for chitosan with properties suitable for food and medical applications.