Abstract: In this study, we investigated the influence of partial substitution of medium-gluten wheat flour (MWF) and whole wheat flour (WWF) with defatted Tenebrio molitor powder (DTP) at various levels (0%, 5%, 10%, 15%, and 20%; m/m) on the pasting, farinographic properties, extensographic, and microstructural properties of composite doughs, as well as on the quality of the resulting steamed bread. The results showed that the addition of DTP reduced the viscosity of wheat flour, but the effects on MWF and WWF were different. With increasing level of DTP replacement, the farinograph quality number rose from 56.00 ± 1.00 to 63.00 ± 1.00 in MWF and from 75.00 ± 1.00 to 100.67 ± 1.53 in WWF. The incorporation of DTP decreased the extensibility of both MWF and WWF doughs. After 45 min of proofing, DTP reduced the resistance to extension of MWF dough but increased that of WWF dough. Compared with the control group, the specific volume of ordinary steamed bread (made from MWF) decreased with increasing level of DTP, whereas that of whole wheat steamed bread initially increased and then decreased, reaching its maximum value (2.06 mL/g) at a substitution level of 5%. The addition of DTP resulted in increased hardness and decreased springiness of ordinary steamed bread, while the chewiness was maintained at a stable level. For whole wheat steamed bread, DTP incorporation contributed to enhanced springiness and chewiness. Moreover, the nutritional value was significantly improved with increasing level of DTP substitution. This study systematically revealed the process adaptability and nutritional and functional characteristics of DTP as a substitute for MWF and WWF, providing a theoretical basis and technical support for the innovative application of novel insect proteins in flour-based food systems.

Key words: defatted Tenebrio molitor powder; wheat flour; farinographic properties; texture; steamed bread