A novel variable power microwave (VPM) drying technology for lowering energy consumption and improving the in vitro protein digestibility of black solider fly larvae

In this study, a novel variable power microwave (VPM) drying process that can automatically and continuously adjust microwave power according to temperature feedback was developed to dry black soldier fly larvae (BSFL). The influence of VPM and constant power microwave (CPM) drying on the drying time, energy consumption, and product quality of BSFL and the potential relationship between BSFL quality and microstructural properties were investigated. The results showed that VPM drying could reduce 17.14% ∼ 27.50% of the drying time and 3.37% ∼ 12.24% of the energy consumption compared with CPM drying. BSFL protein produced by VPM drying exhibited higher digestibility. VPM drying decreased the formation of β-sheets and disulfide bonds within the protein, reducing the aggregation of protein molecules. Scanning electron microscopy and differential scanning calorimetry analysis also demonstrated that VPM-dried BSFL products had smaller protein particle sizes and less protein denaturation. VPM drying can reduce energy consumption while improving BSFL drying efficiency and help to maintain the quality of dried products. The control system that can adjust the microwave power in real time according to the temperature feedback can be easily applied to the continuous tunnel microwave drying equipment widely used in the food industry to realize large-scale VPM drying of insects. The results obtained in this study can help to improve insect-based product quality by using VPM drying and provide technical support for edible insects as an alternative protein source in the future.