Influence of mealworms (Tenebrio molitor larvae) and their protein derivatives on the structural and rheological properties of tofu

This study investigates the effects of incorporating mealworms into tofu, regarding its structural and rheological properties. Tofu samples were prepared using only soybean flour (S), or by replacing soybean flour with mealworms (M), mealworm protein isolate (MPI), or mealworm protein hydrolysate (MPH) at a 1:1 ratio (SM, SMPI, and SMPH, respectively). Results revealed that S partial substitution with M, MPI, and MPH affected the particle size, polydispersity index, and zeta potential of soymilk. Intrinsic fluorescence and surface hydrophobicity showed the early formation of large aggregates in SMPI. As for tofu, gelation of SM mainly occurred due to soybean protein-protein interactions, suggesting that M can prevent gelation, as evidenced by the SDS-PAGE and ATR-FTIR patterns. SMPI had the highest ionic bonds, hydrogen bonds, and hydrophobic interaction content, whereas S had the highest SS bond content. Furthermore, SMPH, enriched with small molecules, exhibited the highest proportion of random coil and disrupted amide bands, leading to limited protein-protein interactions. Finally, apparent viscosity of soymilk, temperature sweep during tofu preparation, frequency sweep, and microstructure analyses of tofu indicated that MPI contributed to hardness (927.9 g/cm2) and gel-like properties, while M and MPH led to softer (135.0 g/cm2 and 32.0 g/cm2, respectively) and more liquid-like tofu compared to S (504.3 g/cm2). In conclusion, this study provides insights into selecting mealworm derivatives with varying structural and rheological properties, enhancing their applicability in gel-type food systems.