*3.6. Scanning Electron Microscopy and Microstructure of Wholemeal Flours*

The abovementioned methods of examining the degree of damage to the microstructure of the endosperm, especially starch granules, as well as other methods that we did not use in our work (e.g., amperometric measurement of damaged starch content according to ICC No. 172/1, on SDmatic, Chopin Technologies, Villeneuve-la-Garenne, France) always affect some aspect that occurs in the condition of starch in the given flour.

Therefore, the samples of the examined flours were subjected to scanning electron microscopy, which (at different levels of magnification) clearly shows both the condition, shape, and constitution of individual flour particles and (at higher magnification, 2500×) shape and possible deformation of individual starch granules. Scanning electron microscopy of samples of examined wholemeal flours are shown in Figure 3a–d.

The spherical particles represent starch (small and large starch grains). Some large starch grains are slightly deformed and damaged mechanically on their surface. The other particles were fragments of the disintegrated portions of the outer and inner coating layers of the cereal grains. The portion of the protein matrix was also visible.

In summary, the images show that with the relatively gentle setting of the disintegration parameters mentioned above (residence time and resulting heating of the flour particles), the grain disintegration is relatively uniform and starch granules are not significantly damaged (e.g., compared to the standard roller grinding process).

**Figure 3.** *Cont*.

**Figure 3.** Images of microstructure of wheat (**a**), rye (**b**), spelt (**c**), and buckwheat (**d**) wholemeal finely granulated flours from scanning electron microscopy.

#### **4. Conclusions**

The evaluation of the structure and properties of wholemeal flours produced in the Mahltechnik Görgens GmbH grinding device, depending on the disintegration conditions and the type and properties of the raw material, is currently still at the beginning. Several types of these flours were examined, depending on the source: common wheat, spelt, rye, and buckwheat flours. It turns out that when the mill was set to the abovementioned retention time of the grist in the grinding zone, there was easy and fast disintegration of rye and common wheat. The disintegration of spelt and buckwheat grains was more complicated and not sufficiently fine granulation was achieved under the given conditions.

The study results of the impact of the disintegration process on the microstructure of the endosperm, especially in the degree of damage to starch granules, show that disintegration in this mill may indeed appear promising. We can achieve fine granulation of flours, including fine granulation of bran particles for some cereals and other grains. At the same time, an undesirable degree of damage to the microstructure of the endosperm was not caused.

Further investigation of the influence of parameters of this type of disintegration process on the quality of the resulting flours will be definitely needed, as well as exploring the possibility of technological applications of these special wholemeal flours.

**Author Contributions:** Conceptualization, P.S.; methodology, M.S., L.J., and I.Š.; software, I.Š.; validation, I.Š. and M.S.; formal analysis, L.J. and I.Š.; investigation, P.S.; resources, P.S. and M.S.; data curation, P.S.; writing—original draft preparation, P.S.; writing—review and editing, P.S. and M.S.; visualization, P.S. and M.S.; supervision, P.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by METROFOOD-CZ project MEYS Grant No: LM2018100.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank Mlýn Perner Svijany, Ltd., Svijany, Czech Republic, for providing the materials (flours) used for experiments. The authors acknowledge Ivana Laknerová, Food Research Institute Prague, Czech Republic for technical support.

**Conflicts of Interest:** The authors declare no conflict of interest.
