This study was conducted to reveal the effect of milk-clotting enzyme (MCE) produced by Bacillus licheniformis on the texture of Cheddar cheese during ripening. Cheddar cheese and Cheddar cheese analogue were prepared with the MCE and designated as C_DF and C_D3, respectively, and commercial chymosin was used as a control (C_CF). The changes in the texture, rheology and microstructure of cheese during ripening were analyzed. The results were as follows: The hardness of the three cheeses increased with maturation time, while the elasticity and chewiness presented a downward trend. The hardness, springiness and chewiness of C_DF were the lowest. The scanning electron microscope (SEM) results showed that the compactness of the protein structure decreased with increasing maturity, and the structure of C_DF was looser than that of C_CF. The rheological results showed that the storage modulus and loss modulus decreased with increasing ripening time up to six months and increasing sweep temperature. The tan δ value decreased during the ripening process, indicating that the fluidity of cheese decreased with increasing ripening time. The fluidity and fusibility of C_DF were better than those of the other groups. The above results indicated that the mechanical properties of cheese made with Bacillus licheniformis MCE were better than those made with commercial rennet, while the latter had harder texture and denser protein network structure.

Tenebrio molitor rennet (TMR) was prepared and the effects of preheating milk at different temperatures on its coagulation behavior and hydrolytic properties were evaluated, and the structure of milk curds was characterized by Fourier transform infrared (FTIR) spectroscopy and laser scanning confocal microscopy (LSCM). The results showed that the water-holding capacity of curds increased significantly with the increase in preheating temperature (P < 0.05), while the particle size, apparent viscosity and storage modulus G´ increased initially and then decreased (P < 0.05); the particle size and apparent viscosity reached their maximum of 15.07 and 0.51 at 45 ℃, respectively. The production of casein glycomacropeptide (CGMP) and the degree of hydrolysis (DH) were not significantly changed with increasing temperature from 45 to 55 ℃ (P > 0.05). The secondary structure and microstructure indicated that the flexibility, stability and compactness of curds were the best at 45 ℃. At this temperature, the water-holding capacity and whey OD value of TMR-coagulated curd tended to be stable when compared with that coagulated by commercial rennet (CR), and the particle size significantly increased. Meanwhile, TMR-coagulated curd exhibited a continuous, irregular and compact network structure, indicating good coagulation properties. Therefore, the optimum coagulation temperature for TMR was 45 ℃. This study provides a theoretical basis and reference for the development and application of new insect-derived rennet.