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Advisor(s)
Abstract(s)
Fractionation of edible insects and their rearing by-products can lead to expanded industrial applications and
extraction of value-added products. The main goal of this study was to extract chitin and synthesise chitosan
from three different insect sources – Tenebrio molitor larvae, adult Acheta domesticus and A. domesticus rearing
by-products (legs and wings). Furthermore, the physicochemical, structural, and bioactive properties of insectderived
chitin and chitosan were characterised and compared to commercial crustacean-based samples. Chitin was
isolated from defatted sources through chemical hydrolysis followed by decolourisation and was deacetylated with
a strong alkaline solution to synthesise chitosan. Notably, A. domesticus rearing by-products yielded the highest
chitin and chitosan content. Chitin and chitosan derived from insects exhibited physicochemical and structural
characteristics consistent with the α-polymorphic form, similar to the commercial samples. Differences were found
in surface morphology, with insect-derived samples presenting large and irregular flakes and porosity, while the
crustacean-derived samples presented irregularly arranged fibres and a more regular and smoother surface. As
for antioxidant activity, although all chitosan samples demonstrated poor DPPH radical scavenging activity, this
study showed for the first time that insect-derived chitosan presents lipid peroxidation inhibition ability. All
chitosan samples presented antimicrobial activity against different pathogenic bacteria, with K. pneumoniae being
the most susceptible strain. Nevertheless, there is potential for enhancement of the biological properties through
modifications on the molecular weight and deacetylation degree. This research introduces the potential of cricketrearing
by-products as sustainable sources of chitosan with functional bioactive properties.
Description
Keywords
Antimicrobial Bioactivity Circular Economy Entomophagy Lipid Peroxidation