Residence time and in vitro digestion model of the black soldier fly (Hermetia illucens) larva midgut

A key challenge for the design and sustainable operation of black soldier fly larvae (BSFL) processing facilities is reliable and efficient waste treatment and bioconversion rate when operating with different biowastes. Currently, a lack of a complete process understanding and control over the large number of biological, microbial and chemical processes, results in high performance variability or low performance, affecting day-to-day operation, the sustainability and scalability of the technology and production of high-value insect-derived products. The limitations of feeding experiments to study BSFL processing are being more and more recognized. This research is the first attempt to mimic digestion by BSFL in vitro. Working towards identifying reliable model input parameters, this research determined for the first time the amount of biowaste ingested and the residence time in the different midgut regions. Using the residence time estimates, artificial feeds and biowastes were digested in the in vitro digestion model. Biowaste performance was predicted based on concentrations of digestion products and compared to feeding experiment results in order to assess the ability of the model to predict in vivo results. Similar to other farmed animals, in vitro digestion models could be a powerful tool to understand BSFL processing and increase its performance.