## 3 Results and Discussion
### Physical Characteristics of Bread Samples  
Figure 1 shows the bread obtained with different levels of protein concentrates in comparison with the control bread. The physical characteristics of the bread samples are presented in Table 4.  
A significant decrease (\(p\) < 0.05) in bread volume, porosity and elasticity was noted with the addition of protein concentrates in the bread receipt; the decrease being more obvious in the case of PP than SP additions. The use of PP significantly decreased (\(p\) < 0.05) the bread volume in a concentration-dependent trend; the PP bread volume was between 1.5- and 2.1-fold lower towards the wheat bread control. In the case of the SP breads, the volume was between 1.2- and 1.3-fold lower than the control. However, no significant difference (\(p\) > 0.05) regarding bread volume between the 10 SP and 15 SP breads was observed. The physical and chemical interactions between gluten and the components from the protein concentrates contributed to the volume lowering. The bread volume was highly negatively correlated with the protein content (\(r\) = \(-\)0.9356). The results are in line with other studies reported previously on the impact of pea protein isolate [3] or soy protein [10] on bread volume. The incorporation of protein concentrates decreased the crumb porosity by up to 47.3% (for 15 PP bread) and 12.5% (for 15 SP bread). There was a negative correlation between the crumb porosity and protein content (\(r=-0.9559\)). Another similar finding was observed in relation to the elasticity and protein content (\(r=-0.8782\)). Measurements of the bread colour parameters showed that all supplemented breads were darker than the control bread. \(L^{*}\) value (lightness parameter) significantly decreased (\(p<0.05\)) with the inclusion of concentrates. The highest lightness was obtained for 5 SP bread, whereas the lowest lightness was in the 15 PP bread. For each of the three levels of substitution used, the PP breads were darker than the SP breads (\(p<0.05\)). Protein supplemented breads showed significantly (\(p<0.05\)) higher redness (a* parameter) and yellowish (b* parameter) values than the bread control. Both parameters significantly increased (\(p<0.05\)) relative to the level of additions. Bread 15 SP had the highest a* and b* values,  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Bread**} & \multirow{2}{*}{ \begin{tabular}{c} **Volume** \\ **(cm\({}^{3}\)/100** \\ **g)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Crumb** \\ **Porosity** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Elasticity** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **L*** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **a*** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **b*** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **C*** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{\ \begin{tabular}{c} **h*** \\ **(\%)** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **AE** \\ **(\%)** \\ \end{tabular}  } \\ \hline Control & 324 \(\pm\) 2 a & \(\  
showing a more reddish and yellowish crumb colour. Among the protein supplemented beads, sample 5 SP had the smallest C* value, a lower chroma value indicating a less strong colour. The highest value for the hue angle (h\({}^{\circ}\)) for the control bread indicated yellowish tones. The hue angle was significantly reduced in the bread crumb of the supplemented breads (\(p<0.05\)). In order to establish the colour differences between the samples, \(\Delta\)E was calculated. The total change in crumb colour was higher in the PP than SP breads. Only sample 5 SP resulted in colour differences towards the control that were not noticeable to the human eye (\(\Delta\)E \(<3\)). It is stated that values for \(\Delta\)E higher than 3 are visible to the human eye [28].