Sequential Extraction and Characterisation of Lipids, Proteins, and Chitin from Black Soldier Fly (Hermetia illucens) Larvae, Prepupae, and Pupae

Abstract

Over the past years, several insect species have gained increased attention as feedstock for food, feed, and industrial applications. One such species is Hermetia illucens, whose larvae can convert low-value organic waste into valuable fat- and protein-rich biomass. Previous research on extracting their lipids, proteins, and chitin has repeatedly focused on one life stage, while in practice different life stages coexist in the same rearing batch. In this study, the feasibility of the sequential extraction of said components from the larval, prepupal, and pupal stage of H. illucens was investigated. Additionally, the chemical composition of the life stages and their extracts was analysed. Following the lipid extraction with petroleum ether, insect proteins were extracted via solubilisation at pH 11.0 and precipitation at pH 4.0. This procedure delivered protein recoveries ranging between 27 and 57% for the three life stages, with the extracts having high protein contents (85–98%). After protein extraction, the residual impure chitin was treated sequentially with HCl and NaOH for further purification. No residual amino acids were detected by UPLC analysis of the purified chitin, which showed acetylation degrees of ± 90%. Overall, it was concluded that the extraction procedure is indeed suitable for all investigated life stages of H. illucens, allowing for the extraction high-value biomolecules for use in industrial applications.