Energy consumption, physical properties, protein structure and digestibility of edible insects dried using three methods

Abstract

This study evaluated the effects of three drying techniques, tray drying, roasting and microwave vacuum drying, on the physical properties, secondary structures, in vitro protein digestibility and X-ray tomographic structure of crickets (Acheta domesticus) and mulberry silkworm pupae (Bombyx mori L.). The protein contents of dried crickets and silkworm pupae were 49-54% and 51-53% (dry basis), respectively. Roasting produced a significantly higher browning index than the other two methods for crickets and silkworm pupae. The microwave vacuum-dried crickets exhibited the lowest hardness, with hardness values of approximately half those of the tray-dried and roasted crickets. Tray-drying and microwave vacuum drying silkworm pupae produced similar hardness values, which were lower than that of roasted silkworm pupae. The energy consumption of the tray dryer was the lowest, followed by the roaster and microwave vacuum dryer. No significant changes in the secondary protein structure of dried silkworm pupae were observed. A significant decrease in α-helix and β-turn and increase in β-sheet was observed in roasted crickets. Cricket and silkworm pupae powders produced from all drying techniques could be easily digested (90-95% digestibility). This work presents valuable knowledge for understanding the effects of different drying techniques on the properties of dried edible insects, aiming to support the production of alternative and sustainable protein sources for the growing population to improve food security.