# Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake
## 3 Results and Discussion
### Influence of the Grinding on the Particle Size Distribution  
Particle size is one of the most important properties affecting the flow properties of powders used as raw materials, as well as the textural and sensory properties of the products in which powders are used. In general, during the grinding process, feed particles are broken down into smaller particles that become more reactive due to a larger specific surface area, which is beneficial in processes involving heat and mass transfer [41; 42]. The effects of grinding time as well as cooling with liquid nitrogen on particle size are shown in Table 3.  
The rapeseed cake was ground for 2, 4, 8, and 12 min with cryocooling (samples CC) or without cooling at room temperature (samples RT). For RT samples, particle size decreased with grinding time, ending after 12 min with a 44.4% decrease from the original median particle size. The grinding duration affects the particle size of different crops [43], but it is important to emphasize that the effect of grinding duration also depends on the properties of the ground material [41]. For samples CC, the reduction in particle size was significantly higher (\(p<0.05\)) than for samples RT. For example, the median particle size decreased to 164 \(\upmu\)m after only 2 min of grinding, which according to the Tukey test is comparable to the particle size measured for the sample RT after 12 min of grinding (175 \(\upmu\)m). The need for shorter grinding times is very important when considering the economics of particle size reduction, as it also means that less energy is required and only a small amount of liquid nitrogen is needed to speed up the process. After 12 min of grinding under liquid nitrogen, a significant reduction in particle size was achieved, with the resulting particles being only 15% of the original size. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **d(0.1)** & **d(0.5)** & **d(0.9)** & **D\({}_{32}\)** & **Span\({}^{5.\xi\xi}\)** & **Specific Surface** \\  & **(\(\upmu\)m) \({}^{5.\xi}\)** & **(\(\upmu\)m) \({}^{5.\xi}\)** & **(\(\upmu\)m) \({}^{5.\xi}\)** & **(\(\upmu\)m) \({}^{5.\xi}\)** & **Area \({}^{5.\xi}\)** (m\({}^{2}\)/g)** \\ \hline RC & 128.2 \(\pm\) 3.8 a & 393.6 \(\pm\) 9.0 a & 881.6 \(\pm\) 19.7 a & 238.8 \(\pm\) 6.0 a & 1.9 \(\pm\) 0.0 g & 0.010 \(\pm\) 0.0006 h \\ \hline
2 RT & 60.1 \(\pm\) 0.3 b & 273.4 \(\pm\) 2.0 b & 770.9 \(\pm\) 6.2 b & 130.6 \(\pm\) 0.9 b & 2.6 \(\pm\) 0.0 d & 0.019 \(\pm\) 0.0000 g \\
4 RT & 48.5 \(\pm\) 1.0 c & 229.4 \(\pm\) 7.1 c & 698.4 \(\pm\) 20.3 c & 108.6 \(\pm\) 2.1 c & 2.8 \(\pm\) 0.0 c & 0.022 \(\pm\) 0.0006 f \\
8 RT & 41.3 \(\pm\) 0.5 d & 202.4 \(\pm\) 5.0 d & 669.7 \(\pm\) 13.6 c & 95.1 \(\pm\) 1.1 d & 3.1 \(\pm\) 0.0 b & 0.026 \(\pm\) 0.0006 e \\
12 RT & 33.5 \(\pm\) 0.4 f & 174.9 \(\pm\) 5.0 e & 615.2 \(\pm\) 10.6 d & 79.7 \(\pm\) 1.1 ef & 3.3 \(\pm\) 0.0 a & 0.031 \(\pm\) 0.0006 d \\ \hline
2 CC & 39.6 \(\pm\) 2.9 de & 164.2 \(\pm\) 2.8 e & 360.4 \(\pm\) 1.5 e & 83.1 \(\pm\) 4.2 e & 1.9 \(\pm\) 0.0 fg & 0.029 \(\pm\) 0.0015 d \\
4 CC & 35.5 \(\pm\) 0.1 ef & 137.4 \(\pm\) 0.1 f & 288.2 \(\pm\) 1.1 f & 75.1 \(\pm\) 0.2 f & 1.8 \(\pm\) 0.0 h & 0.033 \(\pm\) 0.0000 c \\
8 CC & 20.7 \(\pm\) 0.4 g & 92.3 \(\pm\) 0.2 g & 204.9 \(\pm\) 0.7 g & 49.8 \(\pm\) 0.5 g & 2.0 \(\pm\) 0.0 f & 0.049 \(\pm\) 0.0006 b \\
12 CC & 13.8 \(\pm\) 0.2 h & 61.8 \(\pm\) 1.2 h & 148.8 \(\pm\) 1.0 h & 34.3 \(\pm\) 0.5 h & 2.2 \(\pm\) 0.0 e & 0.071 \(\pm\) 0.0012 a \\ \hline \hline \end{tabular} \({}^{\xi}\) Grinding time had significant influence (\(p\leq 0.05\)); \({}^{\xi}\) grinding temperature had significant influence (\(p\leq 0.05\)); \({}^{\xi}\) interaction of the grinding time and temperature had significant influence (\(p\leq 0.05\)); values with different letters in each column are statistically different (\(p\leq 0.05\)) according to [PERSON]’s multiple comparison tests.  
\end{table}