Drying Kinetics, Apparent Moisture Diffusivity, and Energy Performance of Black Soldier Fly Larvae in a Rotating-Tray Hot-Air Dryer

Abstract

Fresh black soldier fly larvae (BSFL) have a high moisture content that complicates storage and requires energy-intensive postharvest drying. This study evaluated the effects of drying-air temperature and tray rotation speed on BSFL drying kinetics, energy performance, and moisture transport in a rotating-tray hot-air dryer. A 3 × 3 factorial experiment was conducted at 50, 60, and 70 °C and tray rotation speeds of 0, 5, and 10 rpm, with three independent replicates, while drying-air velocity was maintained at 3.0 m s−1. Drying time decreased from 31.0 h at 50 °C and 0 rpm to 6.5 h at 70 °C and 10 rpm. The latter condition achieved the highest drying efficiency (49.11%) and lowest specific energy consumption (4.60 MJ kg−1 water removed). Comparable values were obtained at 60 °C and 10 rpm (49.07% and 4.61 MJ kg−1 water removed, respectively). Among nine thin-layer models evaluated for the six rotating-tray treatments at 5 and 10 rpm, the Midilli model provided the best fit. Apparent effective moisture diffusivity (Deff) increased from 0.2457 × 10−9 to 1.2946 × 10−9 m2 s−1, while apparent activation energy ranged from 67.39 to 68.46 kJ mol−1. Rotating-tray drying accelerated BSFL dehydration and improved engineering performance; however, microbial safety and product quality require separate evaluation before food or feed recommendations can be made.