## 3 Results  
### The Effect of Native Flax Cake and Lupine Flour on Wheat Bread Properties  
The purpose of the first experiment was to determine the highest acceptable level of the native additive flax cake and lupine flour to wheat bread and to evaluate the quality of the bread prepared. Wheat bread, with the addition of 5-20% of native flax cake and lupine flour, was prepared. The appearance loaves of bread are shown in Figures 1 and 2. The obtained loaves of bread were evaluated in terms of their physical properties as well as sensory features (Tables 1 and 2). The quality of bread depends on the chemical composition of the flour, the dough mixing process, its fermentation, and baking conditions. One of the distinguishing features of bread quality is the load volume. The loaves with high volume are usually more attractive to consumers. It was found that the increased share of flax cake and lupine flour resulted in a decrease in bread-specific volume (Tables 1 and 2). For the smallest addition, up to 5%, these differences were not statistically significant (\(p\geq 0.05\)), but with a 10% substitution of wheat flour with flax cake and lupine flour, the bread had a significantly smaller volume (\(p=0.038\) and \(p=0.043\), respectively). With the addition of 20% flax cake, the specific volume decreased by 22%. Slightly smaller differences were noted (18%) when lupine flour was added. The effect of flax flour and flax cake addition on the volume of bread was also studied by [PERSON] et al. [3]. They found a significant decrease in the volume of bread with flax cake addition compared to the control bread. It was related to the amount of  
Figure 1: Wheat bread with addition of native flax cake (1—control wheat bread not-containing flax cake; 2–5—experimental bread with addition of native flax cake in the amount: 5—5%, 4—10%, 3—15%, 2—20%). Figure 2: Wheat bread with addition of native lupine flour (1—control wheat bread not-containing lupine flour; 2–5—experimental bread with addition of native lupine flour in the amount: 2—5%, 3—10%, 4—15%, 5—20%). the added flaxseed component rather than to its form (flour vs. cake). In the research of [PERSON] and [PERSON], no difference in the volume of bread with the addition of flax meal was observed, even though the addition was 20% [20]. [PERSON] et al. [21] analyzed the effect of the addition of flour from the selected legume, and they showed that the addition of lupine flour in the amount of 5% does not affect the volume of wheat bread, but the increased addition causes its reduction. In the experiment by [PERSON] et al. [7], the addition of lupine flour at the level of 10% did not significantly reduce the bread volume, but with larger addition, such a phenomenon was observed. The volume and structure of the bread crumb depend on the quality and quantity of gluten, which is the main structural factor of wheat bread. The gluten matrix formed during the kneading of the dough traps carbon dioxide bubbles in the dough during fermentation and baking. Replacing part of the wheat flour with another raw material that does not contain gluten proteins and contains a lot of other proteins and mucilage impedes the creation of a gluten network [22]. Flax cake and lupine flour are characterized by high water absorption because of their fiber content [3; 7; 8; 23]. During the dough formation process, absorbed water surrounds protein molecules, which makes it difficult for gliadins and glutenins to bond. Furthermore, in the case of flaxseed enrichment, a fungistic activity has been reported [24], which could hinder the growth rate of yeast and reduce carbon dioxide production and dough expansion. The addition of flax cake and lupine flour influenced the color of the bread. In the case of flax cake, the change was more significant than with lupine flour. Bread containing 5% of lupine flour was almost the same color as the control sample (\(\Delta\)E = 2.1), whereas the color of bread with 5% of flax cake differed from the control sample (\(\Delta\)E = 12.1).