Effect of killing and drying methods on physicochemical traits, microbial count and sensory properties of Tenebrio molitor larvae

Abstract The present study investigated the effect of two killing methods and three drying processes on physical-chemical, microbiological and sensory characteristics of Tenebrio molitor (TM) larvae. Nine week-old larvae were assigned to four groups: (i) BO, blanching in boiling water at 100 °C for 180 s and drying in oven at 60 °C for 73 h; (ii) BM, blanching at 100 °C for 180 s and drying in microwave at 103 °C for 17 min; (iii) FM, freezing at −60 °C for 1 h and drying in microwave at 103 °C for 15 min; (iv) CA, cryogenic freezing at −90 °C for 12 min and drying in controlled atmosphere at 54 °C for 48 h. Physical characteristics, nutritional composition, and microbial counts of dried larvae were assessed alongside visual, olfactory, and overall acceptance. Groups BO, BM, and FM exhibited lower water activity and higher pH ( ) than CA. On a fresh matter basis, these groups showed higher nutritional value, with increased protein, lipid, energy, mineral, polyunsaturated fatty acid, and amino acid contents ( and ). While group CA preserved fresh larvae’s colour, it had elevated Enterobacteriaceae and sulphite-reducing bacteria. Furthermore, larvae from CA and BO received lower sensory scores compared to the other groups. In conclusion, blanching with oven drying, and blanching or freezing with microwave drying effectively preserve nutrition and ensure microbiological safety. However, blanching or freezing with microwave drying emerged as the preferred methods for consumer visual, olfactory, and overall acceptability.