*2.1. Flour Production*

The flours tested in this study were produced on a special mill from Mahltechnik Görgens GmbH (Dormagen, Germany). It is an impact mill with a vertical axis of rotation, which was not originally intended for grain processing, but which was included in a special production line in the company Mlýn Perner Svijany (Svijany, Czech Republic) and from which the grinding of cereals and pseudocereals into wholemeal flours achieves remarkable results.

The principle of the grinding process is the disintegration of the grist between specially shaped grinding segments rotating in several levels above each other and a specially modified inner shell of the wall of the grinding device (Figure 1). The material is kept suspended in the air stream throughout the disintegration, while it is possible to regulate the residence time of the grist in the grinding chamber and thus also its granulation. Thanks to this arrangement, the flour is not exposed to such thermal stress as when grinding on conventional grinding and roller mills.

The temperature in the grinding chamber ranges from 50 to 90 ◦C, while the temperature of the grist is in the range of 30–80 ◦C depending on the setting of the parameters of the special mill. The residence time of the grist in the grinding chamber is regulated by setting the parameters of the screen of the control plansifter located behind the mill. With sensitive control of the mill parameters, it is possible to achieve, on the one hand, very fine granulation of the bran parts, but on the other hand, there may not be more extensive damage to the starch granules either mechanically or thermally. The aim of our work was to verify these assumptions on selected samples of flour.

**Figure 1.** Scheme of grinding equipment. Description of the equipment parts: 1—grain input; 2—grinding zone; 3—sieving zone, regulation of the granulation; 4—rotation axis.

#### *2.2. Determination of Moisture, Ash, Protein, and Fiber*

The moisture content was determined by standard ICC (International Association for Cereal Science and Technology) No. 110/1, content of ash was specified by ICC No. 104/1, and protein content was measured using the Kjeldahl method (factor 5.7) (ICC No. 105/2). Soluble (SDF), insoluble (IDF), and total (TDF) fiber content was determined using a commercial Total Dietary Fiber enzyme kit from Megazyme (Ireland) according to the approved AOAC (Association of Official Agricultural Chemists) 991.43 method (determination of fiber by enzymatic-gravimetric method) on the Fibertec system (Tecator Foss, Höganäs, Sweden). The results of duplicates of moisture, ash, protein, and fiber determination were repeated three times.

#### *2.3. Flour Granulation*

The sieve analysis was performed according to previously valid Czechoslovak state standards. The sample weight amounted to 100 g, and it was sieved using a KS 1000 rotary sieve (Retsch, Haan, Germany) at a frequency of 100 rpm for 5 min. The set of sieves, equipped with chains, consisted of sieves with mesh sizes of 400, 300, 250, 200, 180, 150, 125, and 90 μm. Sieve analysis was performed in triplicate for each sample and the results were averaged.

#### *2.4. Solvent Retention Capacity Profile*

The physical-and-chemical test profile of retention capacity (SRC) was determined according to the AACC (American Association of Cereal Chemists) 56-11 methodology. The solvent retention capacity (SRC) is expressed as the weight of solvent retained by the flour after centrifugation of the flour suspension with the solvent under the given conditions. It is expressed as a percentage by weight of flour. The result is based on 14% moisture of flour. Four solvents are used independently to profile the SRC values: SRC water (demineralized water), SRC aqueous sucrose solution (50% *w*/*w*), SRC aqueous sodium carbonate solution (5% *w*/*w*), and SRC aqueous lactic acid solution (5% *w*/*w*). By combining these four SRC values, the quality profile of the flour can be determined, and its baking and technological properties can be predicted. In general, lactic acid SRC is associated with glutenin characteristics, sodium carbonate SRC with damaged starch levels,

and sucrose SRCs with pentosans characteristics. The SRC of water is affected by all these components of flour. The results of duplicates of SRC profile parameters determination were repeated three times.

#### *2.5. Determination of Falling Number*

Estimation of alpha-amylase activity and degree of starch damage was performed using a Falling Number instrument (type 1400, Perten Instruments, Hägersten, Sweden). The procedure corresponded to the EN ISO 3093 standard, i.e., the weight of the flour sample corresponded to the current value of the flour moisture. An appropriate laboratory shaker of Polish origin (Wytrz ˛asarka type SZ, biogenet, Józefów, Poland) was used to create the suspension. The results of two experiments of determination of Falling Number were verified (the results may differ not more than 5% of their mean value). There were three replicates performed in the same way for the statistical evaluation.
