Structural Analysis and Processing Characterization of ChitinsExtracted from Different Sources.

The characteristics of three different types of chitin extracted from commonly used seafood organisms; namely crabs, shrimps, and squids were investigated. X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) were employed to analyze these chitins' polymorphic structure and morphology. Bulk and tapped density measurements, along with Kawakita analysis, were used to assess the flowability and compression behaviour of the chitin powders. Chitin extracted from crabs and shrimp exhibited the α-polymorphic form, while chitin from squid showed the β-polymorphic form. SEM images of the two forms revealed distinct differences in chitin layer arrangement, with the α-form appearing more compact due to the anti-parallel alignment of its polymer chains. Both bulk and tapped density measurements and the calculated Hausner ratio (HR) and Carr Index (CI) indicated poor flowability for these chitins. However, Kawakita's analysis of compression and compaction properties demonstrated that both polymorphs are compressible, though they differ in their extent of compaction. Regardless of their source, chitin compacts exhibited high crushing strength. Based on the observed morphology, flowability, and compression characteristics, a blend of α- and β-polymorphic chitin could be an effective excipient for pharmaceutical solid dosage forms.