# Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake
## 3 Results and Discussion
### Influence of the Grinding on the Rapeseed Cake Quality  
As expected, grinding had no effect on the fatty acid composition of the residual oil in the produced rapeseed cake (Table 4). The grinding process was much too short, and the final temperatures of the cake in the experiments conducted at room temperature were far too low for oxidation processes to occur. Sterol content and sterol composition, on the other hand, were influenced by the grinding process (Table 5). Stigmasterol was under direct influence of grinding temperature (\(p<0.05\)), with generally higher amounts in CC samples according to Tukey test. The levels of brassicasterol and \(\Delta\)5-avenasted were also affected by grinding temperature, but also by the duration of the process and the interaction of the two factors. Time and the interaction of time and temperature had significant effects on the content of campesterol, \(\Delta\)5,24-stigmastadienol, and concentration of total sterols, while \(\beta\)-stiosterol, the dominant sterol in rapeseed cake, was affected only by the interaction of the factors studied. According to the Tukey test, the highest amounts of total sterols were found in the sample CC ground for twelve minutes. These values were slightly higher but comparable to those of the RT samples ground for 8 and 12 min, respectively. Longer mechanical treatment by the ball mill probably resulted in greater disruption of the cell structure and thus better availability and extractability of the sterols. Using wheat bran as an example, it has been shown that cryogenic grinding causes destruction of the cell wall, resulting in the release of the cell contents and thus higher bioavailability of certain compounds. It also facilitates the interaction between the compound and the solvent and the extraction of the desired components [45]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Fatty Acid (\% of Total)**} & \multicolumn{8}{c}{**Sample**} \\ \cline{2-10}  & **2 RT** & **4 RT** & **8 RT** & **12 RT** & **2 CC** & **4 CC** & **8 CC** & **12 CC** \\ \hline C14:0 & nd \({}^{\star}\) & 0.1 \(\pm\) 0.0 & nd \({}^{\star}\) & nd \({}^{\star}\) & nd \({}^{\star}\) & nd \({}^{\star}\) & nd \({}^{\star}\) \\ C16:0 & 5.1 \(\pm\) 0.0 & 5.1 \(\pm\) 0.0 & 5.1 \(\pm\) 0.1 & 5.1 \(\pm\) 0.0 & 5.1 \(\pm\) 0.0 & 5.1 \(\pm\) 0.2 & 5.1 \(\pm\) 0.0 & 5.2 \(\pm\) 0.0 \\ C16:1 & 0.4 \(\pm\) 0.0 & 0.4 \(\pm\) 0.0 & 0.4 \(\pm\) 0.0 & 0.4 \(\pm\) 0.0 & 0.5 \(\pm\) 0.0 & 0.5 \(\pm\) 0.0 & 0.5 \(\pm\) 0.0 \\ C17:1 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 & 0.1 \(\pm\) 0.0 \\ C18:0 & 1.9 \(\pm\) 0.0 & 2.0 \(\pm\) 0.0 & 2.0 \(\pm\) 0.2 & 2.0 \(\pm\) 0.1 & 1.9 \(\pm\) 0.0 & 1.9 \(\pm\) 0.0 & 1.9 \(\pm\) 0.1 & 1.9 \(\pm\) 0.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Fatty acid composition of rapeseed cak additionally grinded at room temperature (RT) and with cryogenic cooling (CC). The content of IDF was not affected by the grinding process and particle size reduction, while it significantly affected soluble dietary fiber (SDF) (Figure 1). The amount of SDFP was significantly affected by the grinding time and the interaction of grinding time and temperature. According to the Tukey test, their amount increased with increasing grinding time until 8 th minute, both with and without cryogenic cooling, and then decreased after 12 min. Samples ground for 12 min contained significantly lower amounts of SDFP than samples prepared in shorter procedures. The increase was also observed by [PERSON] et al. [46] on an orange peel. The reason could be the release of soluble fibres from stable complexes with a longer grinding time, while further grinding leads to mechanical destruction of the molecules and consequently to a decrease in their amount. This hypothesis is confirmed by the fact that the number of SDFS increased slightly (by about 8%) after 12 min of grinding with cryogenic cooling.