## 3 Results
### Study of Effect of Rotor Speed and Knife Design on Temperature of Meat-and-Bone Paste
As the rotational frequency increases from 1000 to 3000 rpm, the mean particle diameter decreases; however, speeds beyond 3000 rpm confer negligible gains in particle fineness while exacerbating frictional forces and blade wear. A further constraint arises from adiabatic heating: mechanical friction and plastic deformation can convert 20-30% of the input energy into heat, causing the paste's temperature at discharge to rise by 5-10 \({}^{\circ}\)C and, under continuous operation, to reach 50-60 \({}^{\circ}\)C. Such thermal elevations impair protein functionality and reduce product viscosity. To maintain the requisite thermal conditions and achieve consistent, high-quality grinding, it is, therefore, essential to supply precooled raw material, employ water-jacketed housings, and, when necessary, operate in an intermittent mode [19]. _Study of Rheological Properties_  
Figure 5: Sizes of bone particles after grinding using control knife (**a**) and experimental knife (**b**). During the next stage of the study, the dynamic viscosity and shear stress of meat- and-bone paste were investigated. For the control working tool, it was found that at a rotor speed of 1000 rpm, the dynamic viscosity was 55,418 Pa-s and the shear stress was 38,256 mPa-s. At 2000 rpm, dynamic viscosity increased to 60,550 Pa-s and shear stress to 39,263 mPa-s. At 3000 rpm, these parameters reached 67,809 Pa-s and 45,907 mPa-s, respectively. However, at 4000 rpm, a slight decrease in dynamic viscosity to 62,354 Pa-s and in shear stress to 41,240 mPa-s was observed (Figures 6 and 7). With the experimental configuration, the dynamic viscosity and shear stress followed a similar trend. At 1000 rpm, the dynamic viscosity was 59,589 Pa-s and shear stress was 35,578 mPa-s. At 2000 rpm, the values increased to 61,158 Pa-s and 38,873 mPa-s, respectively. At 3000 rpm, the maximum dynamic viscosity, 71,507 Pa-s, and a shear stress  
Figure 6: Changes in dynamic viscosity of meat-bone paste depending on rotor speed (different letters (a–c) above lines indicate significant differences between rotor speeds, \(p<0.05\)). Figure 7: Changes in shear stress of meat-bone paste depending on rotor speed (different letters (a–c) above lines indicate significant differences between rotor speeds, \(p<0.05\)). of 43,531 mPa\(\cdot\)s were recorded. A further increase to 4000 rpm resulted in a decrease in viscosity to 64,237 Pa\(\cdot\)s and shear stress to 40,031 mPa\(\cdot\)s. The dynamic viscosity of the meat-bone paste was evaluated across all grinding conditions. The typical viscosity range required for sausage emulsions is between 40,000 and 80,000 Pa\(\cdot\)s, which ensures proper emulsion stability, texture formation, and ease of stuffing during processing [20]. The results demonstrate that as rotor speed increased from 1000 to 3000 rpm, both dynamic viscosity and shear stress consistently increased for both working tool types. This behavior is consistent with the general physical law that during the transition from coarse to fine grinding of meat and meat-bone raw materials, the rheological properties change markedly: the viscosity of the suspension and the yield strength increase [21]. This phenomenon is attributed to the reduction in particle size, leading to an increase in the total specific surface area and the formation of a denser network structure through intensified protein-fat and water-bonding interactions [22]. The change in rheological parameters depends on several factors. A finer particle size (higher dispersity) results in increased viscosity and shear resistance due to the stronger interparticle interactions within the pseudoplastic system [23]. The design characteristics of the grinding equipment, specifically the geometry of and the clearance between the rotor and stator, as well as the shape and density of the cutting teeth, critically influence the degree of grinding.