# Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake
## 3 Results and Discussion
### Quality of the Rapeseed Cake
One of these components are dietary fibres, which accounts for the largest portion of rapeseed cake, 30.7%. However, dietary fibre can also have some beneficial properties that depend mainly on their nature. [PERSON] and [PERSON], in their review [33], reported the average values of several different studies, and the amounts of total dietary fibre were comparable to the results of this study. The vast majority of the dietary fibre fraction, more than 83%, was insoluble dietary fibre (IDF) (Table 1). This is the undesirable fraction, consisting mainly of non-starch polysaccharides (cellulose and a variety of non-cellulose polysaccharides) and polyphenic lignin, components resistant to hydrolysis by enzymes in the digestive tract. Their antinutritional properties are reflected in their inhibitory effect on the digestibility of nutrients [34; 35]. However, soluble dietary fibre (SDF), which represent a desirable but small proportion of rapeseed dietary fibre (about 17% in the present study), could have a beneficial effect on total and LDL cholesterol levels [36]. Polyphenolic compounds are also among the components with ambiguous characteristics. They are known for their antioxidant and free radical scavenging activities and potential health benefits [37]. However, high concentrations of phenolic compounds, as found in our study, where phenolic compounds accounted for 2.1% of the produced cake \begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & & **RC** \\ \hline  & Brassicasterol & \(11.6\pm 0.5\) \\  & Campesterol & \(29.4\pm 1.0\) \\  & Campestanol & \(1.1\pm 0.0\) \\  & Stigmasterol & \(0.7\pm 0.1\) \\ Sterol (\% of total) & \(\beta\)-sitosterol & \(51.5\pm 0.5\) \\  & \(\Delta\)5-avenasterol & \(3.5\pm 2.3\) \\  & \(\Delta\)7-avenasterol & \(0.8\pm 0.4\) \\  & \(\Delta\)7-stigmasterol & \(0.1\pm 0.1\) \\  & \(\Delta\)5-24-stigmastadenol & \(1.3\pm 0.1\) \\  & Total sterols (mg/100 g) & \(148\pm 6\) \\ \hline Dietary fiber & IDF & \(25.7\pm 0.6\) \\ (\%) & SDFP & \(3.0\pm 0.1\) \\ SDFS & \(2.0\pm 0.0\) \\ \hline \end{tabular} IDF— insoluble; SDFP—soluble in water but precipitated in 78% ethanol; SDFS soluble in water and not precipitated in 78% ethanol.  
\end{table} 
Table 1: _Cont._(Table 2), have negative effects on the nutritional value and organoleptic properties of rapeseed cake. Phenolic compounds are known to be responsible for the dark colour, bitter taste, and astringency of rapeseed meal. As mentioned earlier, phenolic compounds and their oxidised products can also interact with amino acids, enzymes, and other food components [6]. Free phenols accounted for nearly 70% of the total phenols in this study (Table 2). Of these, free phenolic acids accounted for less than 15%, and the remainder were esterified phenolic compounds. The dominant phenolic compound was sinapine, choline ester of sinapic acid (607 mg/100 g). In contrast to previously reported results [10], sinapic acid was not the predominant free phenolic acid in the produced cake. The reason for this could be due to the production of oil and cake, i.e., the conditioning of the seeds, which leads to the decarboxylation of sinapic acid and the formation of conalol, decreasing the concentration of sinapic acid in the cake. The absence of a carboxyl group gives conalol a more lipophilic character than its precursor, which is why it accumulates in the oil [38] and its concentration in the cake was low (9 mg/100 g). The bound phenolic compounds represent a smaller fraction of phenolics and accounted for slightly more than 30% of the total phenolic compounds. Among them, sinapic acid was the dominant compound. It accounted for 80% of the bound phenolic compounds. Minor phenolic compounds were ferulic acid, p-coumaric acid, and syringaldehyde. Tannins are another group of phenolic compounds. Their concentration in rapeseed cake was slightly lower than 0.5%.