## 3 Results and Discussion
### Characteristics of Quality Parameters of Wheat Flour and Sugar Beet Pulp Mixtures  
#### 3.2.1 Parameters Characterized the Protein Complex of Wheat Flour and Sugar Beet Pulp Mixtures  
The results of the quality characteristics of the protein complex of the flour samples are presented in Table 2.  
Samples of wheat flour (WF) and sugar beet pulp (SBP) mixtures were characterized in the context of a protein complex by gluten characteristics and the Mixolab test. The statistical analysis showed that the quantity of the SBP additive and the type of fortification significantly influenced the protein characteristics of the flour mixtures (Table 2). SBP, as a source of dietary fiber incorporated into wheat flour dough, strongly interfered with protein association. An increase in the SBP additive significantly decreased the gluten content from 28.3 (0% SBP) to 25.8% (10% SBP) and slightly lowered the gluten quality determined by the gluten index (GI) from 96 to 93. However, the decrease in GI was not important in the technological aspects. The reduction in gluten content results from the increase in the SBP addition, which is gluten-free [29]. The SBP addition altered the rheological properties of the dough tested by Mixolab(r). We observed that an increase in SBP addition caused a significant increase in water absorption (from 60.0% to 71.0%), which is a direct effect of the high fiber and ash contents in both types of SBP. These results were consistent with the work by [PERSON] et al. [30] and [PERSON] et al. [50]. The dietary fibers present in SBP have previously been described by authors [26; 51; 52] for their increased resistance and reduced dough extensibility. Dietary fibers in dough mixtures increase resistance due to the aggregation of fibers and interactions with wheat flour proteins. Their influence depends on the molecular weight, branching, and the amount of added fiber and may lead to changes in gluten and secondary gluten structures [53]. The addition of SBP also positively affected the dough's strength and increased the development time T1 and stability (from 1.84 to 9.37 min and from 9.56 to 10.94 min, respectively). The typical wheat flour with an ash content of around 0.75% d.m. is characterized by time T1 in a range of 1.2-7.3 min and stability in a range of 8.6-11.7 min [54]. As a result, SBP, even in a small amount (5%), can improve the dough's stability when prepared from weak flours, especially dedicated for bread production, which needs long mixing and fermentation times. A similar effect of adding SBP to wheat flour was found by [PERSON] et al. [50]. However, [PERSON] et al. [55] found that adding sugar beet fiber strongly decreased its heating stability when added singly. The tested wheat control flour sample was characterized by the typical dough characteristics for flours produced in Poland concerning gluten protein weakening (C2 in the 0.43-0.57 N-m and C2-C1 in the range 0.50-0.66 N-m) [54]. The effect on the dough's characteristics was shown in the rising value of the torque in points C2 and lowering the difference between the parameters C2 and C1, representing resistance to mixing. Based on all these parameters, it was shown that the dough with the addition of SBP is more stable for mechanical processing and should not cause problems in the baking lines of large baking plants. An opposite effect was obtained by [PERSON] et al. [55], where sugar beet fiber led to a decrease in the torque value C2. [PERSON] et al. [55] claimed that the effect of the fiber's blend on the Mixolab(r) parameters and the increase in C2 is a consequence of some impediments in the protein unfolding. Flour mixtures with molasses SBP were characterized by a lower gluten content, water absorption, and dough stability to mixing, measured by time T1 and stability compared to the unmolasses SBP. One of the reasons may be the lower total dietary fiber content in the molasses SBP than in the unmolasses SBP and a higher carbohydrate content.