# Assessing the Performance of Different Grains in Gluten-Free Bread Applications
## 3 Results and Discussion
### Breads Characterization  
Sorghum and millet breads are characterized by lower specific volumes and higher crumb firmness compared to quinoa and rice flour breads (Table 3). [PERSON] et al. [40] reported an improvement of the specific volume and crumb firmness of gluten-free breads based on heat-treated sorghum flour compared to the unheated flour. The authors noted that these results are possible due the modification of sorghum proteins by oxidizing the free sulfhydryl groups. Moreover, [PERSON] et al. [2] suggested that the lack of glyco- and phospholipids in sorghum flour might be a reason for the lower volume of the bread prepared with sorghum flour compared to the wheat. In addition to starch, the properties of the lipids influence to high extent the crumb firmness. The quinoa bread had the highest specific volume and lowest crumb firmness. [PERSON] et al. [1] reported enhanced specific volume of the bread made with quinoa flour compared to the bread made with a blend of rice and corn flours. The authors explained these results through the better ability of the dough prepared with quinoa flour to retain a high amount of gas. It is well known that the proteins from rice flour do not have great gas retention properties [41]. The high gas volume resulting throughout fermentation was stabilized within the network during baking, resulting in a nice structure with homogeneously distributed fine pores. It was considered that different surface-active components present in quinoa flour, such as peptides or polar lipids, might contributed to the stabilization of the gas bubbles. In addition, the viscoelastic properties of the dough might be optimized such as to allow easier and more efficient gas inclusion and stabilization. Furthermore, [PERSON] et al. [1] noted that specific volume of bread increased when quinoa flour was used to replace the quinoa whole \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Properties** & **Quinoa Flour** & **Sorghum Flour** & **Millet Flour** & **Rice Flour** \\ \hline Fineness module & 2.31 \(\pm\) 0.03 & 1.63 \(\pm\) 0.02 & 1.90 \(\pm\) 0.02 & 2.85 \(\pm\) 0.03 \\ - Particles size 500–315 \(\upmu\)m, \% & 35.9 \(\pm\) 0.11 & 10.0 \(\pm\) 0.10 & 18.7 \(\pm\) 0.10 & 59.5 \(\pm\) 0.11 \\ - Particles size 315–125 \(\upmu\)m, \% & 46.0 \(\pm\) 0.10 & 80.7 \(\pm\) 0.12 & 74.9 \(\pm\) 0.12 & 32.7 \(\pm\) 0.10 \\ - Particles size \(<\) 125 \(\upmu\)m, \% & 18.1 \(\pm\) 0.09 & 9.3 \(\pm\) 0.08 & 7.0 \(\pm\) 0.07 & 7.8 \(\pm\) 0.05 \\ \hline Damaged starch, \% & 4.44 \(\pm\) 0.05 & 8.17 \(\pm\) 0.06 & 5.27 \(\pm\) 0.05 & 3.85 \(\pm\) 0.05 \\ \hline L* & 81.46 \(\pm\) 0.16 & 81.62 \(\pm\) 0.16 & 83.79 \(\pm\) 0.29 & 83.89 \(\pm\) 0.62 \\  & a* & 1.32 \(\pm\) 0.05 & 4.49 \(\pm\) 0.02 & 2.62 \(\pm\) 0.01 & 0.59 \(\pm\) 0.01 \\ Color values & b* & 15.28 \(\pm\) 0.12 & 12.45 \(\pm\) 0.39 & 15.18 \(\pm\) 1.12 & 15.33 \(\pm\) 0.06 \\  & C* & 15.34 \(\pm\) 0.43 & 13.23 \(\pm\) 0.01 & 15.40 \(\pm\) 0.02 & 15.34 \(\pm\) 0.02 \\  & h\({}^{\circ}\) & 56 \(\pm\) 0.00 & 51 \(\pm\) 0.00 & 54 \(\pm\) 0.01 & 57 \(\pm\) 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical properties of whole quinoa, sorghum, millet and rice flows. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Physical Properties**} & \multicolumn{4}{c}{**Breads Prepared With**} \\ \cline{2-5}  & **Quinoa Flour** & **Sorghum Flour** & **Millet Flour** & **Rice Flour** \\ \hline Specific volume, cm\({}^{3}\)/100 g & 192.22 \(\pm\) 0.12 & 152.35 \(\pm\) 0.10 & 164.39 \(\pm\) 0.11 & 181.04 \(\pm\) 0.12 \\ Crumb firmness, N & 10.81 \(\pm\) 0.14 & 21.47 \(\pm\) 0.32 & 25.70 \(\pm\) 0.15 & 13.74 \(\pm\) 0.23 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Physical properties of quinoa, sorghum, millet and rice breads. flour. They considered that the positive effect registered on the volume of the bread was the result of removing the embryo hull components out of the whole flour. As previously shown, the bran particles might interfere with gas cells, affecting the porosity and specific volume bread [42].