Upcycling Byproducts from Insect (Fly Larvae and Mealworm) Farming into Chitin Nanofibers and Films

Abstract

Nowadays, environmental concerns make us rethink the way that we live and eat. In this regard, alternative protein sources are emerging; among them, insects are some of the most promising alternatives. Insect farming is still an infant industry, and to improve its profitability and environmental footprint, valorization of the byproducts will be a key step. Chitin as the main polysaccharide in the exoskeleton of insects has a great potential in this regard and can be processed into high value-added materials. In this study, we extracted and fibrillated chitin fibers from fly larvae (Hermetia illucens) and compared them with commercial chitin from shrimp shells. A mix of chitin and cellulose fibers was also extracted from mealworm farming waste. The purified chitinous fibers from different sources had similar chemical structures as shown by Fourier transform infrared and nuclear magnetic resonance spectroscopies. After mechanical fibrillation, the nanostructures of the different nanofibers were similar with heights between 9 and 11 nm. Chitin nanofibers (ChNFs) from fly larvae presented less nonfibrillated fiber bundles than the shrimp-derived analogue, pointing toward a lower recalcitrance of the fly larvae. ChNF suspensions underwent different film-forming protocols leading to films with tensile strengths of 83 ± 7 and 71 ± 4 MPa for ChNFs from shrimp and fly, respectively. While the effect of the chitin source on the mechanical properties of the films was demonstrated to be negligible, the presence of cellulose nanofibers closely mixed with ChNFs in the case of mealworm led to films twice as tough. Our results show for the first time the feasibility of producing ChNFs from insect industry byproducts with high potential for valorization and integral use of biomass.

Chitin Determination in Residual Streams Derived From Insect Production by LC-ECD and LC-MS/MS Methods

“…Chitin in the exuviae of house cricket at various instar stages was 9.6-9.9%, slightly lower than the reported chitin content (10.9%) in the adult exoskeleton of different cricket species (Gryllus bimaculatus) (Kim et al, 2017). The estimated chitin content in mealworm exuviae was 7.9-8.6%, lower than the value of 11% and 18% obtained in previous studies (Song et al, 2018;Pasquier et al, 2021). Discrepancies in chitin yield between studies could be attributed to differences in species, life stages, body parts, and the extraction procedure itself.…”

“…We assume that the less successful chitin purification from mealworm and cricket exuviae was due to their high lipid content since hydrophobic repulsion was observed throughout the study, thus reducing the accessibility of the acid and alkali solutions to solubilize minerals and proteins (Tan et al, 2021). The outer region of insect exuviae, especially that of mealworm larvae, contains a considerable amount of lipid (Pasquier et al, 2021), which serves as a barrier to protect the insect from abrasion and infection (Roer et al, 2015). Removal of the lipid fraction was attempted by pre-treating the exuviae with n-hexane according to a previously described method (Choi et al, 2017), but this additional step did not yield sufficient improvement in reducing the hydrophobic repulsion.…”

Nanochitin: Chemistry, Structure, Assembly, and Applications

“…Nanochitin can be directly applied as a versatile building block to produce films. The latter can be optically transparent following dense packing and reduced light scattering/adsorption (Figure a). , Films produced from mushroom-derived ChNF (containing glucans) were translucent and exhibited a strong brown color originated from melanin contained in the spores and gills of the mushrooms (Figure b). , Moreover, porous and aggregated structures produced a mismatch in the RI between air and nanochitin, producing strong light scattering and leading to opaque films . To obtain highly transparent films, nanochitin of suitable structural dimensions and with proper annealing processes should be considered.…”

Tenebrio molitor Beetle as a “Nonvegan” Adjuvant to Flame Retardants in Tannic Acid-Based Epoxy Thermosets

“…So far, the associated agricultural sector has provided insect larvae on a large scale merely as a feed supplement in vertebrate farming and is expected to grow in the years ahead. Utilizing insect byproducts for materials science merges sustainability with advanced material properties . Among the byproducts of T.…”