Black Soldier Fly (Hermetia illucens L.) larvae as a sustainable protein source for animal feed

Abstract

Black soldier fly (Hermetia illucens L., Diptera: Stratiomyidae) larvae (BSFL) farming offers a dual solution for Africa by converting organic waste into nutrient-rich protein for animal feed and organic fertiliser (frass), addressing urban waste challenges and reducing reliance on unsustainable imports, such as fishmeal. However, realising these potential hinges on developing safe, efficient, scalable, and economically viable processing methods suitable for African conditions. A comprehensive literature search was conducted across academic databases (Google Scholar, ScienceDirect, Scopus, PubMed, Web of Science) using keywords such as "black soldier fly larvae processing," "nutritional composition," and "antimicrobial properties." Peer-reviewed studies, technical reports, and conference papers were included to assess the impacts of harvesting, decontamination, drying, and nutrition. Optimising key steps is essential: robust harvesting (sieving or auto-collection depending on larval stage, substrate humidity, and particle size), effective microbial reduction via post-harvest processing (feed withdrawal, washing protocols needing refinement, especially for contaminated waste), killing methods (freezing, blanching, asphyxiation, mechanical disruption, each impacting nutritional quality, microbial safety, and animal welfare differently), and decontamination. Drying methods (low-temperature air, high-temperature air, oven, microwave, and freeze-drying) significantly influence the final product's safety, nutritional retention, and economic viability, involving trade-offs between speed, energy efficiency, protein and fat preservation, and cost. The nutritional composition of BSFL (protein: 27.54-55.42%, fat: 8.10-57.80%, ash: 3.90-33.0%, chitin: 3.87-9.62%) and functional properties (antimicrobial peptides, lauric acid; up to 52% of lipids) are highly variable, primarily dictated by the rearing substrate. This offers opportunities for tailored production but requires strict control of substrate safety to avoid heavy metal accumulation. Processing choices also directly impact protein digestibility and amino acid profiles. Optimising these processing parameters is fundamental to ensuring a safe, nutritious, and stable insect meal that meets regulatory standards, reduces post-harvest losses, improves economic viability for small-scale farmers, and unlocks the role of BSFL in circular economies, food security, waste management, and climate-resilient agriculture across Africa.