## 3 Results
### Study of Effect of Rotor Speed and Knife Design on Temperature of Meat-and-Bone Paste  
A series of experiments were carried out to evaluate the impact of rotor-stator geometry and rotor speed on the quality of poultry bone-meat paste. The rotor speed ranged from 1000 to 4000 rpm, with a fixed gap of 0.1 mm and an initial meat-bone mixture temperature of 2 \({}^{\circ}\)C. The control tool left bone fragments larger than 1 mm, whereas the experimental tool effectively eliminated larger fragments, likely because the shallower tooth angle created more shear and prolonged contact. Varying the rotor speed influenced the final paste temperatures. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Rotor–Stator Type**} & \multicolumn{4}{c}{**Rotor Speed, rpm**} \\ \cline{2-5}  & **1000** & **2000** & **3000** & **4000** \\ \hline Control & 264.71 \(\pm\) 4.91  & 352.94 \(\pm\) 3.99  & 439.02 \(\pm\) 8.41  & 428.57 \(\pm\) 4.27  \\ \hline Experimental & 240.00 \(\pm\) 4.45  & 333.33 \(\pm\) 4.47  & 400.00 \(\pm\) 4.70  & 375.00 \(\pm\) 4.03  \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Influence of rotor speed on mass flow rate (kg/h) in colloid milling. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Rotor–Stator Type**} & \multicolumn{4}{c}{**Rotor Speed, rpm**} \\ \cline{2-5}  & **1000** & **2000** & **3000** & **4000** \\ \hline Control & 0.27 \(\pm\) 0.00  & 0.36 \(\pm\) 0.01  & 0.45 \(\pm\) 0.01  & 0.44 \(\pm\) 0.01  \\ \hline Experimental & 0.24 \(\pm\) 0.00  & 0.34 \(\pm\) 0.01  & 0.41 \(\pm\) 0.01  & 0.38 \(\pm\) 0.01  \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Volumetric flow rate (m\({}^{3}\)/h) at various rotor speeds. At 1000 and 2000 rpm, the outlet temperature was moderately elevated (18-24 \({}^{\circ}\)C), while at 3000 rpm it dropped to around 8 \({}^{\circ}\)C in the control setup and 11 \({}^{\circ}\)C in the experimental setup. At 4000 rpm, the paste overheated to 26-32 \({}^{\circ}\)C, risking protein denaturation and reduced product quality. Industrial practice recommends a final temperature near 10-15 \({}^{\circ}\)C for optimal meat processing [17], making 3000 rpm the most favorable rotational speed tested (Figure 3). This temperature change can be explained by the longer period that the meat-bone mixture spends in the rotor-stator chamber at lower speeds, which permits greater heat accumulation and transfer to the product over an extended processing interval. In contrast, at 3000 rpm, the shorter exposure and increased throughput enable quicker passage through the mill and more effective heat dissipation, resulting in a lower final paste temperature. At lower speeds, the time required to achieve fine grinding increases, and at 4000 rpm, there is little additional benefit in fragment size but a marked rise in temperature. Consequently, 3000 rpm provides the best balance of throughput, fine grinding, and adequate temperature control. The experimental rotor-stator geometry offers added assurance against the presence of coarse bone fragments, although preventing temperature buildup at higher speeds requires careful operation. _Study of Particle Size Distribution_  
The data for the control knife configuration indicate that at lower rotor speeds (1000-2000 rpm), a substantial proportion of large bone particles remained in the paste (for example, at 1000 rpm, 24.32% of the particles had a size of 2 mm). Increasing the rotor speed to 3000 rpm reduced the fraction of such large fragments (2 mm) to 10.04%, and further to 7.47% at 4000 rpm. However, even at these higher speeds, more than half of the particles remained approximately 1 mm or larger, indicating that only partial fine grinding of the bone material was achieved (Figure 4). Particles exceeding 1 mm in diameter are generally considered unacceptable for emulsified meat products, as their presence imparts a gritty or sandy mouthfeel, diminishes product smoothness, and may lead to consumer rejection due to perceived defects in texture and overall eating quality.