Investigating the effect of larval instar, post-harvest treatments, and substrate on the nutritional profile of black soldier fly larvae (Hermetia illucens)

Context Black soldier fly larvae (BSFL) is considered to be a sustainable animal feed ingredient, that feeds in different organic waste streams. It is well established that the nutritional profile of BSFL is influenced by the substrate used. However, the impact on the overall nutritional quality of the larvae when reared on food waste streams in an industrial setting is unknown. Aims The objective of this study is to determine the nutritional quality and chemical composition of BSFL from two instars (fifth and sixth) reared on five different food waste streams from two different waste facilities and post-harvest treatments. Methods BSFL were reared with five different waste streams, viz. soy waste (S), customised bread–vegetable waste (B), supermarket waste (WL), childcare centre waste (CC) and a food waste mixture (WB); two larvae instars (fifth and sixth) and post-harvest treatments (blanching and drying) were analysed for proximate composition, and amino, fatty acid and mineral contents. Key results The blanching and drying treatments did not affect the chemical composition of the larvae; however, they had a negative effect on fatty acid content and reduced the concentration of certain amino acids. The mineral content of BSFL was increased by drying, whereas blanching did not result in leaching except for sodium. The larval instar played a role in influencing the crude fat and crude protein content, with a higher fatty acid content in sixth instar BSFL. Mineral and amino acid profiles were found to be influenced by both the larval instar and the food waste stream used for rearing. Conclusions This study showed the interdependent relationship between substrate, instars, and the post-harvest treatments in influencing the nutritional properties of the larvae. Implications The outcomes of this study will assist manufacturers in substrate selection and enable them to custom tailor their operations to arrive at a product with desired nutritional properties.