Dielectric properties of black soldier fly larvae at 2.45 GHz, and their dependence with moisture content, temperature, or bulk density

As the global population continues to rise, the demand for traditional food sources, especially animal protein, intensifies, leading to increasing scarcity. The black soldier fly (BSF) larvae are an alternative high protein source (up to 44%) which farming is environmentally sustainable. This contribution aims to increase the industrial processing efficiency by examining the feasibility of using microwave technology at the right larvae instar for its storage. Microwave processing offers advantages such as rapid water removal, nutritional preservation, and microbial reduction. This paper characterizes experimentally the dielectric constant ( ε ′) and loss factor ( ε ′′) of BSF larvae, and their dependency with temperature, moisture content (MC), and bulk density (BD), to enable optimized microwave drying systems. Results show that the permittivity varies significantly with the MC. The decrease of MC, the goal of any drying process, is linked to the BD reduction, and this physical parameter has even a stronger influence on the permittivity. Finally, the temperature increase affects the loss factor, causing an increase of the heating speed. Nevertheless, all these magnitudes combined keeps the larvae dielectric parameters within a range that provides insights for improving the microwave drying efficiency of processed BSF larvae at an industrial scale. • The bulk density of Black Soldier Fly (BSF) larvae has a greater impact on dielectric properties around 2.45 GHz at moisture levels above 50%. • BSF’s microwave drying efficiency drops sharply at moisture levels below 50%. • A cascade configuration of microwave modules optimized for different drying stages can be used for convenient industrial BSF processing. • There is no risk of thermal runaway in BSF microwave processing according to the dynamics of its effective dielectric properties. • Monitoring the BSF payload as an electrical load within a microwave cavity (e.g. through its scattering reflection coefficient) can enable intelligent control of microwave power in continuous or batch processing.