# Influence of Cryogenic Grinding on the Nutritional and Antinutritional Components of Rapeseed Cake
## 4 Conclusions  
Cryogenic grinding is a much more efficient method of reducing particle size than room temperature grinding. Grinding the rapeseed cake with a ball mill for only 2 min at \(-\)196 \({}^{\circ}\)C resulted in the same particle size as grinding for 12 min at room temperature. Twelve minutes of cryogenic grinding resulted in particles about 6.5 times smaller and a specific surface area 7 times larger compared to the starting material.  
Micronization of the rapeseed cake had some effect on the nutritional and antinutritional components, but not to the extent we expected. On the positive side, grinding the cake had no effect on the fatty acid composition of the cake, but the cake ground for 12 min under cryogenic conditions had an increased content of phytosterols. Soluble dietary fibre content also slightly increased with decreasing particle size. However, the content of insoluble dietary fibre was not affected. The mechanical destruction of the cell walls combined with the heat generated during grinding at room temperature resulted in the release of the bound phenolics and thus an increase in the total free phenolic compounds in these samples. The same occurred with the tannins, making them more extractable and consequently resulting in higher tannin concentrations after longer grinding times. However, the best results were obtained in reducing the components that raise the most concerns, glucosinolates. Room temperature grinding reduced glucosinolate content by up to 34%, and even better results were obtained under cryogenic conditions: 43% less after 12 min.  
Although these results are promising, they are not sufficient to recommend micromization as the sole treatment for rapeseed cake. It could be used as a pre-treatment for chemical or biological treatments to reduce antinutritive components, since cell disruption and increase in specific surface area increases the extractability and availability of undesirable components. These studies should also investigate whether the high cost of the cryogenic process is justified, as it did not significantly affect the antinutritional components of rapeseed cake.  
Conceptualization, K.K., D.S., S.B. and D.C.; Data curation, K.K. and N.C.M.; Formal analysis, K.K. and S.B.; Funding acquisition, D.C.; Investigation, M.B., S.D., A.M.J., K.M. and I.R.; Methodology, K.K., N.C.M. and M.B.; Project administration, N.C.M.; Resources, D.S. and D.C.; Supervision, D.C.; Validation, K.K., N.C.M. and S.D.; Visualization, K.K.; Writing--original draft, K.K.; Writing--review and editing, K.K., D.S. and D.C. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Glucosinolate** **(\(\mathbf{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\  
**Funding:** This research was founded by the Croatian Science Foundation (IP-2016-06-3789 project \"From grain by-products to functional food through innovative processing\").  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data that support the findings of this study are available from the corresponding author upon reasonable request.  
**Acknowledgments:** Authors thank [PERSON], Faculty of Agriculture, University of Zagreb for the rapeseed.  
**Conflicts of Interest:** The authors declare no conflict of interest.