Abstract
PurposeChitin purification from remains (pupal exuviae after metamorphosis to adult flies) of Hermetia illucens farming was optimized performing demineralization, deproteinization and bleaching under different conditions. The optimal parameters to obtain high-purity chitin were determined.MethodsDried and ground pupal exuviae, whose composition was initially determined, were demineralized using six different acids. Proteins were removed with a NaOH treatment in which temperature, molarity and duration were varied in a randomized experiment. Bleaching was carried out testing ten different chemicals, including NaOCl, H2O2, solvent mixtures and enzymes. The efficiency of each step was determined to assess the optimal conditions for each of them. The resulting chitin was subjected to spectroscopic characterization.ResultsThe highest demineralization efficiency (90%) was achieved using 0.5 M formic acid for 2 h at 40 °C, confirming the validity of organic acids as a more sustainable alternative to inorganic acids. The treatment with 1.25 M NaOH at 90 °C for 4 h showed the highest deproteinization efficiency, removing 96% of the proteins. Temperature and NaOH concentration were the significant parameters for deproteinization efficiency. The most efficient bleaching treatment was with 6% NaOCl at 60 °C for 1 h (67% efficiency). H2O2 could also be a valid alternative to avoid environmental risk related to chlorine-containing compounds. At the end of the purification process 17% of the original biomass was retained with a chitin content of 85%, corresponding to a chitin yield of 14% related to the initial biomass. Solid-state nuclear magnetic resonance showed that the purified chitin had a degree of acetylation of 96% and X-ray powder diffraction gave a crystallinity index of 74%.ConclusionThis investigation shows an optimized method for extraction of high-purity chitin from H. illucens pupal exuviae, supporting the validity of insect-farming remains as source of this versatile biopolymer.Graphical
Highlights
Chitin is the Earth’s second most abundant polysaccharide after cellulose, being the main structural component of arthropod’s exoskeleton and the cell wall of fungi [1]
We describe the production of pure chitin from one of the major insect processing waste streams, the pupal exuviae
Chitin can be converted into chitosan, a polymer with increased solubility and reactivity provided by free amino groups, which can find a wider range of applications [5, 6]
Summary
Chitin is the Earth’s second most abundant polysaccharide after cellulose, being the main structural component of arthropod’s exoskeleton and the cell wall of fungi [1]. It is a polymer of increasing commercial potential. Chitin can be converted into chitosan, a polymer with increased solubility and reactivity provided by free amino groups, which can find a wider range of applications [5, 6]. In recent years it has become necessary to look for alternative sources to cope with the huge increase in demand expected for chitin and chitosan [8]. Crustacean waste does not have a constant availability throughout the year, its supply is becoming no more sustainable without worsening the depletion of marine resources and the chitin quality is not consistent since the raw materials composition varies [9, 10]
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