# Gluten-Free Sourdough Based on Quinoa and Sorghum: Characterization and Applications in Breadmaking
## 3 Results
### 3.4. Bread Properties  
Sourdough is a key ingredient used for preparing high-quality baked products with various types of flour. The sourdough based on blends of quinoa and sorghum flours was used for preparing GF sourdough bread samples, which were characterized in terms of moisture (Table 9), TPC, antioxidant activity (Table 4), specific volume, color and texture properties (Table 10). The moisture of the bread crumb was measured after cooling the samples to room temperature (1 st day) and after 48 h of storage (3 rd day), while packed in polyethylene bags. In the 1 st day, the crumb moisture ranged between 35.80 and 43.22 g/100g and decreased to 34.48\(-\)41.38 g/100g in the 3 rd day (Table 9) because of the moisture migration to the crust [63]. All GF sourdough bread presented rather low moisture content and might, therefore, exhibit good stability over storage. In agreement with the observations of [PERSON] et al. [26], a slight decrease in the TPC and antioxidant activity of the GF bread was noticed compared to the corresponding sourdough samples (Table 4). Regardless of the starter culture used for preparing the \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{3}{c}{**Crumb Moisture (g/100 g) on 1 st Day**} & \multicolumn{3}{c}{**Crumb Moisture (g/100 g) on 3 rd Day**} \\ \cline{2-7}  & **Q100** & **Q75** & **Q50** & **Q100** & **Q75** & **Q50** \\ \hline C & 43.22 \(\pm\) 0.24 \({}^{\text{\,A}}\) & 38.93 \(\pm\) 0.13 \({}^{\text{\,b}}\)\({}^{\text{\,A}}\) & 36.30 \(\pm\) 0.08 \({}^{\text{\,A}}\) & 41.38 \(\pm\) 0.60 \({}^{\text{\,A}}\) & 37.77 \(\pm\) 0.41 \({}^{\text{\,b}}\)\({}^{\text{\,A}}\) & 35.18 \(\pm\) 0.55 \({}^{\text{\,A}}\) \\ SC1 & 41.19 \(\pm\) 0.04 \({}^{\text{\,B}}\) & 36.14 \(\pm\) 0.05 \({}^{\text{\,B}}\) & 36.29 \(\pm\) 0.05 \({}^{\text{\,b}}\)\({}^{\text{\,A}}\) & 39.50 \(\pm\) 0.36 \({}^{\text{\,A},\text{B}}\) & 34.48 \(\pm\) 0.06 \({}^{\text{\,b}}\)\({}^{\text{\,B}}\) & 34.74 \(\pm\) 0.30 \({}^{\text{\,b}}\)\({}^{\text{\,A}}\) \\ SC2 & 41.58 \(\pm\) 0.05 \({}^{\text{\,B}}\) & 37.60 \(\pm\) 0.06 \({}^{\text{\,b}}\)\({}^{\text{\,C}}\) & 35.80 \(\pm\) 0.50 \({}^{\text{\,A}}\) & 39.81 \(\pm\) 0.30 \({}^{\text{\,a}}\)\({}^{\text{\,B}}\) & 35.98 \(\pm\) 0.06 \({}^{\text{\,b}}\)\({}^{\text{\,C}}\) & 34.76 \(\pm\) 0.40 \({}^{\text{\,c}}\)\({}^{\text{\,A}}\) \\ \hline  & & & & & \\ \end{tabular}
\end{table} 
Table 9: The influence of quinoa flour substitution by sorghum flour and of starter culture used for sourdough fermentation on the crumb moisture in the first and third days of storage at room temperature. sourdough, the highest TPC (_p_ < 0.05) were measured for the Q75-based bread samples. The radical scavenging activity of the GF sourdough bread samples was not significantly influenced by the GF flour blend or the type of starter culture (Table 4). The only exception concerned the Q100 C and Q75 C bread samples, which exhibited the lowest ABTS-RSA of 165.79 \(\upmu\)mols TE/g d.w. and DPPH-RSA of 241.10 \(\upmu\)mols TE/g d.w., respectively. Sorghum flour addition to quinoa flour had no significant influence on the specific volume of the sourdough bread (Table 10). As previously reported by [PERSON] et al. (2016), the dough prepared with quinoa flour has a good ability to retain the gas formed during fermentation. In addition to the proteins originating from flour or peptides released upon lactic acid bacteria action of the native proteins, other compounds like polar lipids from quinoa might participate in the stabilization of the gas in the dough network ([PERSON], 2016; [PERSON] et al., 2016). An improvement in the specific volume and crumb firmness has also been reported in the event of longer fermentation during which more gas is produced. In the case of the GF formulations including 100% and 75% quinoa flour, the lowest specific volumes of 97.1\(-\)100.0 cm\({}^{3}\)/g were obtained for the bread samples prepared with sourdough fermented with SC2 (Table 10).