## 3 Results and Discussion  
Change of Yield Stress, Water-Binding Capacity of Ground Meat, and Energy Characteristics of Grinder Depending on Knife Rotation Speeds and Clearance  
The data on changes in yield stress, water-binding capacity, and energy characteristics depending on knife rotation speed and gap between the knives are presented in Table 2.  
From Figures 5 and 6, it is revealed that the highest values of yield stress and water-binding capacity are observed when the rotation speed of the knives is 4000 rpm and the clearance between the knives is 0.16 mm. The analysis of the graphs of dependencies of yield stress and water-binding capacity on the rotational speed of the working bodies reveals that these parameters also increase with increasing rotational speed. This can be explained by the fact that with increasing rotation speed of the knives, more intensive cutting of particles of meat and bone raw materials takes place. The total surface of the minced meat particles increases, the moisture from the free form transforms into the surface-bonded form, the process of formation of a new structure of minced meat occurs and, as a consequence, the value of the yield stress and water-binding capacity increase. The changes of yield stress and water-binding capacity from the clearance value between the rotating and stationary knives at different rotational speeds were studied. The analysis of the research results shows that these values increase up to the maximum values at a gap of 0.15 mm, and then decrease, regardless of the rotation speed. At this gap, the ratio of ground particles to moisture reaches optimal values. The moisture is maximally bound by proteins from the ground meat and bone raw materials. As the gap increases, the amount of water increases in relation to the proteins that bind them, and the values of yield stress and water-binding capacity decrease. Reducing the gap causes release of intercellular juice and increases the liquid fraction in relation to proteins of meat and bone raw materials. The values of the yield stress and water-binding capacity are also decreased. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Knife Rotation Speed (rpm)**} & **Gap between the Knives (mm)** & \multirow{2}{*}{**Yield Stress (Pa)**} & \multirow{2}{*}{**WBC (\%)**} & **Energy Characteristics (kW)** \\ \hline \multirow{6}{*}{1000} & 0.05 & 704.74 \(\pm\) 12.09  \\ \cline{2-5}  & 0.16 & 742.43 \(\pm\) 9.74  \\ \cline{2-5}  & 0.27 & 666.72 \(\pm\) 8.58  \\ \cline{2-5}  & 0.38 & 635.87 \(\pm\) 7.02  \\ \hline \multirow{6}{*}{2000} & 0.05 & 743.82 \(\pm\) 11.92  \\ \cline{2-5}  & 0.16 & 781.23 \(\pm\) 8.39  \\ \cline{2-5}  & 0.27 & 711.24 \(\pm\) 14.17  & 64.53 \(\pm\) 1.17 & 2.42 \(\pm\) 0.05  & 65.97 \(\pm\) 1.36 & 3.69 \(\pm\) 0.06  & 66.17 \(\pm\) 0.50 & 3.08 \(\pm\) 0.04  & 65.43 \(\pm\) 0.63 & 2.74 \(\pm\) 0.03  & 65.23 \(\pm\) 1.07 & 2.48 \(\pm\) 0.04  \\ \cline{2-5}  & 0.16 & 943.29 \(\pm\) 15.89  \\ \cline{2-5}  & 0.27 & 866.42 \(\pm\) 15.03  \\ \cline{2-5}  & 0.38 & 827.82 \(\pm\) 12.34  \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Changes in yield stress, water-binding capacity, and energy characteristics depending on knife rotation speed and gap between the knives. Figure 5: Variation of the yield stress from the gap and the knife rotation speed. The power consumption of the motor increases as the gap decreases. This can be explained by the fact that with a decreasing gap between the knives, the grinding process is intensified and the friction between the product and the knives increases, which, according to the Rebinder theory, leads to an increase in energy consumption [16,17]. When analyzing the data of power changes, it is clear that increasing the rotation speed of the working bodies together with reducing the gap between the knives corresponds to an increase in power consumption by the electric motor of the machine. So, if the power is 2640 kW at a rotation speed of 4000 rpm and a gap of 0.38 mm, then decreasing the gap to 0.05 mm increases the power to 3806 kW.