## 3 Results
### Study of Effect of Rotor Speed and Knife Design on Temperature of Meat-and-Bone Paste
Thus, minimizing the proportion of such coarse particles is essential to ensure optimal sensory properties in the final product. Figure 3: Changes in meat–bone paste temperature after grinding depending on rotor speed (different letters (a–d) above lines indicate significant differences between rotor speeds, \(p\) < 0.05). In contrast, the experimental rotor-stator configuration demonstrated a significantly greater capability for fine grinding. At 1000 rpm, only 3.67% of bone fragments had a size of 2 mm (compared to 24.32% in the control configuration). Increasing the rotor speed to 3000 rpm further shifted the particle size distribution toward finer fractions: only 1.67% of the fragments remained at 2 mm, while 70.30% were in the 0.1 mm fraction, and 6.24% belonged to the sub-0.1 mm category. At 4000 rpm, the proportion of the finest fraction slightly decreased (to 5.21% for particles smaller than 0.1 mm), but the share of coarse particles (\(\geq\)1 mm) remained minimal. A comparative assessment of the SEM micrographs presented in Figure 5 illustrates the pronounced effect of knife design on bone particle morphology after grinding. In Figure 5a, representing the control knife (45\({}^{\circ}\) tooth angle, 1.5 mm pitch), the bone fragments are predominantly coarse, with many particles ranging from 140 to 380 \(\upmu\)m and a substantial number exceeding 200 \(\upmu\)m in size. By contrast, Figure 5b, which depicts the experimental knife (20\({}^{\circ}\) tooth angle, 0.5 mm pitch), demonstrates a markedly finer and more homogeneous distribution, with most bone fragments measuring between 25 and 70 \(\upmu\)m and the majority remaining below 100 \(\upmu\)m. These microstructural images visually corroborate the quantitative particle size distribution data, confirming that the experimental knife configuration achieves more effective comminution of bone material. This improvement in particle size uniformity is critical for ensuring the functional and sensory quality of meat emulsions. Figure 4: Bone particle size distribution in meat–bone paste depending on rotor speed: (**a**) at 1000 rpm, (**b**) at 2000 rpm, (**c**) at 3000 rpm, (**d**) at 4000 rpm. Thus, the working assembly with a tooth inclination angle of 20\({}^{\circ}\) and a 0.5 mm pitch provided more efficient and uniform grinding of bone inclusions compared to the control design, which left a noticeable portion of fragments \(\geq\)1 mm. Achieving a paste dominated by fractions smaller than 0.5 mm, and particularly by fractions under 0.1 mm, is critical for the production of emulsified sausages, gates, and other finely textured meat products that require the absence of perceptible bone particles to ensure acceptable mouthfeel and consumer safety. Furthermore, the experiments confirmed the critical role of rotor speed: increasing the speed from 1000 to 3000 rpm significantly reduced the proportion of coarse particles, whereas further increases (up to 4000 rpm) offered only marginal additional advantages and caused slight shifts within the finer size classes. Overall, the experimental rotor-stator configuration with the smaller tooth inclination angle (20\({}^{\circ}\)) demonstrated superior fine grinding efficiency, which is important for producing pastes free of noticeable bone inclusions. The fineness of grinding for both meat and meat-bone mixtures is largely governed by the geometric and kinematic characteristics of the mill's working elements. In rotor-stator systems (colloid mills), particle size is adjusted via the rotor's tooth geometry, the stator's orifice pattern, the number of cutting elements, and the inter-element gap [18]. Reducing tooth pitch, increasing edge sharpness, and narrowing the clearance (to as little as 0.1-0.5 mm) facilitate the production of a finely dispersed (colloidal) mass, but these modifications also impose higher power demands on the equipment. Kinematic parameters, most notably rotor speed, directly modulate the rates of abrasion and fragmentation.