# Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake
## 3 Results and Discussion  
### Quality of the Rapeseed Cake  
The quality of rapeseed cake is determined by the composition of macro- and micronutrients and the presence of desirable and undesirable components. Rapeseed cake produced in our laboratory contained 9.5% water, which was due to the addition of water during the production process (Table 1). The oil content of the cake produced was 14%, a result comparable to cakes produced in industry [30]. Since rapeseed cake contains a relatively high amount of oil, the composition of these nonpolar components is important for the incorporation of the by-product in food formulations. The fatty acid composition of the cake affects not only the nutritional value but also the oxidative stability of the cake and the products in which it is used. The fatty acid composition of the residual oil in rapeseed cake is shown in Table 1. According to the Codex Standard for Named Vegetable Oils [31], it can be classified as low erucic acid rapeseed, with oleic acid being the predominant fatty acid and a significant amount of linoleic and linoleic acid in the ratio 2.8:1. Due to its favourable fatty acid composition, rapeseed oil is beneficial to health from various aspects: it reduces the risk of cardiovascular disease, improves lipid and glucose metabolism, and has a positive effect on atherosclerosis and inflammation [32]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & & **RC** \\ \hline \multirow{4}{*}{Quality parameter (\%)} & Water & 9.5 \(\pm\) 0.1 \\  & Oil & 14.1 \(\pm\) 0.3 \\  & Protein & 29.5 \(\pm\) 0.4 \\  & Ash & 6.4 \(\pm\) 0.3 \\ \hline \multirow{4}{*}{Fatty acid (\% of total)} & C14:0 & 0.1 \(\pm\) 0.0 \\  & C16:0 & 5.1 \(\pm\) 0.0 \\  & C16:1 & 0.4 \(\pm\) 0.0 \\  & C17:1 & 0.1 \(\pm\) 0.0 \\ \cline{1-1}  & C18:0 & 1.9 \(\pm\) 0.1 \\ \cline{1-1}  & C18:1 & 64.4 \(\pm\) 0.3 \\ \cline{1-1}  & C18:2 & 19.1 \(\pm\) 0.0 \\ \cline{1-1}  & C18:3 & 6.8 \(\pm\) 0.2 \\ \cline{1-1}  & C20:0 & 0.6 \(\pm\) 0.0 \\ \cline{1-1}  & C20:1 & 1.1 \(\pm\) 0.1 \\ \cline{1-1}  & C22:0 & 0.3 \(\pm\) 0.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Quality parameters, composition of the non-polar fraction and dietary fiber of laboratory produced rapeseed cake (RC). In addition, the sterols of rapeseed oil are known as assistants in lowering the risk of cardiovascular disease. Based on the mass of the cake, the rapeseed cake produced in this experiment contained 148 mg/100 g of sterols (Table 1). The composition of sterols is typical of low erucic rapeseed [31] with \(\beta\)-sitosterol as the dominant sterol (51.5%), followed by campesterol (29.4%) and brassicacetyl (11.6%). The analyzed rapeseed cake contained 6.4% ash. It has already been reported that rapeseed cake and meal are good sources of available calcium, iron, manganese, and selenium. Although they are high in phytate, they are also one of the richest sources of non-phyrate phosphorus [33]. However, the most valuable components of rapeseed cake and the reason for numerous research studies to incorporate it in human nutrition are its proteins, which have a balanced amount of essential amino acids, are rich in sulfur-containing amino acids, and have good functional properties. Their digestibility is reported to be as high as 84%, while egg and milk proteins have a digestibility of 94% and 95%, respectively. Rapeseeed cake proteins have good solubility, emulsification, foaming, and stabilization properties. To date, there are several rapeseed protein products that have been approved by the U.S. Food and Drug Administration (FDA) as safe (GRAS) or by the European Food Safety Authority (EFSA) as novel foods and can be used in a variety of bakery products, fruit and vegetable juices, egg substitute products, and processed meats [2]. Rapeseed cake produced and used in this study contained nearly 30% crude protein (Table 1). Regardless of the enumerated advantages, the use of rapeseed cake as a food source is limited by the presence of antinutritional components.