The Extraction and Characterisation of Chitin and Chitosan from Six Species of Beetles: Demonstrate That Beetles Are a Valuable Source of These Biopolymers

Abstract

This work aimed to extract chitin and chitosan from the exoskeletons of different beetle species and to analyze the properties of chitin and its derivative, chitosan. Chitosan is increasingly acknowledged as a significant primary material for producing a variety of products. Annually, the demand for chitin derivatives increases. To meet this requirement, it becomes imminent to seek novel sources of chitin. This study investigates many beetle species as prospective chitin sources for chitosan synthesis. The chitin content obtained from the dry weight of beetle raw material varied between 7.2% and 42.2%. The extraction percentages of chitosan differed among species, ranging from 13.5% to 89.2% of the chitin weight removed. The XRD analysis of chitin exhibited prominent peaks at 9.2 degrees, 19.2 degrees, 22.8 degrees, and 26.3 degrees. The X-ray diffraction (XRD) patterns of chitosan obtained from six different beetle species exhibit significant peaks at around 8.9°, 20.1°, 25.3°, and 26.5°. The crystallinity index of chitin ranges from 22% to 55%, whereas chitosan exhibits a range of 8.5% to 13.4%; nevertheless, the degree of deacetylation (DDA) of chitosan consistently exceeds 69% across all species. The FTIR spectra of chitin and chitosan from each species exhibited significant variations in the amide III, amide II, and amide I regions. The SEM images of chitin/chitosan from these insects exhibited a combination of flake-shaped structures, nanopores, and nanofibers. The findings indicate that the extraction of chitin and chitosan from beetle exoskeletons is an uncomplicated process that yields a significant amount of these polymers. Chitin and chitosan exhibited SEM-documented morphologies characterized by a reduced number of pores and an increased presence of fibers. The structural analysis has confirmed that the chitin in these species is exclusively in the alpha form. These species serve as exceptional reservoirs of chitin and chitosan.