## 3 Results and Discussion
### The Thermo-Mechanical Properties of Rice Flows  
The Mixolab curves showing the thermo-mechanical behavior of the investigated rice flour samples are presented in Figure 1. Analyzing the Mixolab curves, one can observe that NRF and ARF behaved similarly when subjected to mechanical and thermal constraints. Thus, during mixing at 30 \({}^{\circ}\)C, the consistency of the two doughs increased \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**SRC**} & \multicolumn{3}{c}{**Flour Samples**} \\ \cline{2-4}  & **ARF** & **BRF** & **NRF** \\ \hline W-SRC, \% & 115.49 \(\pm\) 0.50 \({}^{\text{b}}\) & 105.85 \(\pm\) 0.30 \({}^{\text{c}}\) & 124.51 \(\pm\) 0.36 \({}^{\text{a}}\) \\ \hline Ca-SRC, \% & 103.65 \(\pm\) 0.41 \({}^{\text{c}}\) & 110.84 \(\pm\) 0.30 \({}^{\text{b}}\) & 134.33 \(\pm\) 0.25 \({}^{\text{a}}\) \\ \hline Na-SRC, \% & 93.03 \(\pm\) 0.26 \({}^{\text{c}}\) & 101.66 \(\pm\) 0.35 \({}^{\text{b}}\) & 105.27 \(\pm\) 0.23 \({}^{\text{a}}\) \\ \hline SC-SRC, \% & 104.10 \(\pm\) 0.36 \({}^{\text{a}}\) & 84.89 \(\pm\) 0.35 \({}^{\text{c}}\) & 90.18 \(\pm\) 0.17 \({}^{\text{b}}\) \\ \hline LA-SRC, \% & 79.27 \(\pm\) 0.15 \({}^{\text{c}}\) & 95.33 \(\pm\) 0.25 \({}^{\text{b}}\) & 106.01 \(\pm\) 0.34 \({}^{\text{a}}\) \\ \hline Su-SRC, \% & 88.36 \(\pm\) 0.23 \({}^{\text{b}}\) & 82.53 \(\pm\) 0.21 \({}^{\text{c}}\) & 124.57 \(\pm\) 0.35 \({}^{\text{a}}\) \\ \hline \hline \end{tabular}  
* ARF—Arorio rice flour; BRF—Basmati rice flour; NRF—Negro rice flour; W-SRC—water retention capacity; Ca-SRC—CaCl\({}_{2}\) solvent retention capacity; Na-SRC—NaCl solvent retention capacity; SC-SRC—sodium carbonate solvent retention capacity; LA-SRC—lactic acid solvent retention capacity; Su-SRC—sucrose solvent retention capacity. Mean values on the same row not sharing a superscript letter are significantly different (\(p\) < 0.05).  
\end{table} 
Table 2: The solvent retention capacity (SRC) profile of the rice flours. up to 1.43-1.44 Nm quite suddenly, within 1.45-1.97 min at WA1 of 65%, and within 1.28-2.48 min at WA2 of 69.7-70.3% (Table 3). However, the stability of NRF dough is 6.1 min, higher compared to that of ARF (4.5 min), at the same WA1 (65%). In the case of WA2 necessary to obtain the maximum consistency of 1.1 \(\pm\) 0.5 Nm, the situation is maintained, the NRF dough being more stable than the ARF. When a smaller amount of water was used in the dough system (WA1 of 65%), after 8 min of mixing the NRF dough consistency was 1.24 Nm, significantly higher than that of ARF (1.17 Nm) (\(p<\) 0.05). On the other hand, when a larger amount of water was used to prepare the dough, the CS values of ARF and NRF were extremely close, 0.96-0.97 Nm. When compared to the ARF and NRF doughs, the dough from BRF flour reached a significantly lower consistency at WA1 of 65% (\(p<\) 0.05), the dough development being slower (C1 achieved after 8.3 min of mixing), and the stability of the dough significantly higher (9.1 min) (\(p<\) 0.05). Even slower BRF dough development was observed when the WA2 of 66% was used to obtain the maximum consistency of 1.1 \(\pm\) 0.5 Nm. The BRF dough had a high stability in this case as well, the consistency remaining within the limit of 1.1 \(\pm\) 0.5 Nm even after 8 min. In agreement with the observations of [PERSON] et al. [18], the differences in the behavior of NRF dough, on the one hand, and ARF and BRF, on the other hand, can be attributed to the differences in the protein and fiber contents (Table 1), but also to the quality of the proteins. Rice proteins are mainly composed of glutenins and are rich in high molecular weight protein fractions [25]. [PERSON] et al. [26] showed that the proteins in black rice contain a higher amount of glutenins (82.75%), compared to white rice (60%). In addition, there are important differences in other protein fractions: albumin, globulin and prolamins account for 12.61%, 3.41%, and 1.24%, respectively, in the black rice, and for 5%, 10%, and 25%, respectively, in the white rice. Regarding fibers, [PERSON] et al.