## 3 Results and Discussion
### The Influence of SPI Addition on the Thermo-Mechanical Properties of the Gluten-Free Mixtures
Regardless of SPI addition, dough consistency increased over Ph III: the increase rate was lower for the sample with SPI addition (from 1.30 to 1.66 Nm) compared to the control dough (from 1.38 to 1.88 Nm). On the other hand, during Ph IV when the temperature dropped from 90 to 70 \({}^{\circ}\)C (from 1800 to 2100 s), the consistency of the sample with SPI increased by 0.13 Nm (from 1.58 to 1.71 Nm), whereas the control registered no important variation in the consistency (from 1.86 to 1.87 Nm) (Table 2). This behavior could be due to the aggregation of soy proteins during heating. The main soybean proteins, glycinin and \(\beta\)-conglycinin, dissociate into monomers with increasing temperature, exposing a number of hydrophobic patches which might lead to the formation of aggregates and ordered gel structures [29]. In the last phase, the dough consistency increase in the two samples was rather similar: 0.29 Nm (from 1.98 to 2.27 Nm) for the sample with SPI and 0.33 Nm (from 2.18 to 2.51 Nm) for the control sample (Table 2). [PERSON] and [PERSON] [29] mentioned that dough consistency during heating and cooling depends on the amount of soy protein isolate substituting rice flour, and [PERSON] et al. [30] emphasized the importance of soy protein processing conditions on the properties of SPI. When adding 13% SPI to rice flour, [PERSON] and [PERSON] [29] obtained a decrease in C3 and C4 values and an increase in C5 and (C5-C4) values. On the other hand, [PERSON] et al. [28] reported a decrease in C3, C4 and C5 values when incorporating 15% SPI into rice flour; a similar trend was observed by [PERSON] et al. [31] when SPI was added to the wheat flour. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Sample/Parameter** & **CI, Nm** & **C2, Nm** & **C3, Nm** & **C4, Nm** & **C5—C-III, Nm** \\ \hline
50 QF + 50 RF & 0.88 \(\pm\) 0.02 d & 0.15 \(\pm\) 0.01 e & 1.74 \(\pm\) 0.02 b & 1.83 \(\pm\) 0.02 a & 0.65 \(\pm\) 0.002 e \\
50 QF + 40 RF + 10 SPI & 0.80 \(\pm\) 0.02 e & 0.15 \(\pm\) 0.01 e & 1.58 \(\pm\) 0.02 c & 1.60 \(\pm\) 0.02 c & 0.69 \(\pm\) 0.002 c,d \\ \hline
50 QF + 40 RF + 10 sSPI-B & 0.16 \(\pm\) 0.01 j & 0.01 \(\pm\) 0.01 f & 1.15 \(\pm\) 0.01 e & 1.18 \(\pm\) 0.02 e & 0.50 \(\pm\) 0.008 h \\
50 QF + 40 RF + 10 sSPI-N & 0.23 \(\pm\) 0.01 i & 0.03 \(\pm\) 0.01 f & 1.16 \(\pm\) 0.01 e & 1.18 \(\pm\) 0.02 e & 0.39 \(\pm\) 0.002 i \\
50 QF + 40 RF + 10 sSPI-T & 0.18 \(\pm\) 0.01 j & 0.00 \(\pm\) 0.01 h & 1.17 \(\pm\) 0.01 e & 1.20 \(\pm\) 0.02 e & 0.50 \(\pm\) 0.001 h \\ \hline
50 QF + 40 RF + 10 rSPI-B & 1.96 \(\pm\) 0.02 b & 0.30 \(\pm\) 0.01 b & 1.71 \(\pm\) 0.02 b & 1.66 \(\pm\) 0.01 b & 0.67 \(\pm\) 0.013 d \\
50 QF + 40 RF + 10 rSPI-N & 1.56 \(\pm\) 0.02 c & 0.27 \(\pm\) 0.01 c & 1.70 \(\pm\) 0.02 b & 1.64 \(\pm\) 0.01 b & 0.79 \(\pm\) 0.003 b \\
50 QF + 40 RF + 10 rSPI-T & 2.17 \(\pm\) 0.02 a & 0.42 \(\pm\) 0.02 a & 1.91 \(\pm\) 0.02 a & 1.83 \(\pm\) 0.02 a & 0.82 \(\pm\) 0.002 a \\ \hline
50 QF + 40 RF + 10 hSPI-B & 0.46 \(\pm\) 0.01 h & 0.11 \(\pm\) 0.01 f & 1.45 \(\pm\) 0.02 d & 1.44 \(\pm\) 0.02 d & 0.63 \(\pm\) 0.002 f \\
50 QF + 40 RF + 10 hSPI-N & 0.71 \(\pm\) 0.01 f & 0.10 \(\pm\) 0.01 f & 1.44 \(\pm\) 0.02 d & 1.44 \(\pm\) 0.02 d & 0.55 \(\pm\) 0.010 b \\
50 QF + 40 RF + 10 hSPI-T & 0.50 \(\pm\) 0.01 g & 0.18 \(\pm\) 0.01 d & 1.55 \(\pm\) 0.02 c & 1.57 \(\pm\) 0.02 c & 0.71 \(\pm\) 0.006 c \\ \hline \hline \end{tabular}  
* QF—quina flour; RF—rice flour; SPI—gov protein isolate; sSPI, rSPI and hSPI—soluble, insoluble and total soy protein hydrolysate fraction, respectively, obtained with bromelin (B), Neutrase (N) and trypsin (T). Different superscript letters associated with values in same column indicate significant differences among results, as resulted from ANOVA and Tukey post hoc test at \(p<0.05\).  
\end{table} 
Table 3: The influence of gluten-free flour supplementation with soy proteins or peptides on the Mixolab parameters of dough.