# Effect of Citrus Fiber on the Rheological Properties of Dough and Quality of the Gluten-Free Bread
## 3 Results and Discussion
### Rheological Properties of Dough
\begin{table}
\begin{tabular}{c c c c c} \hline
**Parameter** & **Control GFB** & **10\% CF** & **15\% CF** & **20\% CF** \\ \hline K\({}^{\prime}\) (Pa-s\({}^{n}\)) & 4017.0 \(\pm\) 138.4 \({}^{\mathrm{a}}\) & 4024.1 \(\pm\) 489.0 \({}^{\mathrm{a}}\) & 5156.7 \(\pm\) 411.8 \({}^{\mathrm{b}}\) & 6503.5 \(\pm\) 492.1\({}^{\mathrm{c}}\) \\ \hline n\({}^{\prime}\)(-) & 0.158 \(\pm\) 0.003 \({}^{\mathrm{b},c}\) & 0.166 \(\pm\) 0.006 \({}^{\mathrm{c}}\) & 0.154 \(\pm\) 0.001 \({}^{\mathrm{b}}\) & 0.142 \(\pm\) 0.006 \({}^{\mathrm{a}}\) \\ \hline r\({}^{2}\)\(>\) & 0.996 & 0.995 & 0.996 & 0.994 \\ \hline K\({}^{\prime\prime}\) (Pa-s\({}^{n^{\prime}}\)) & 1385.6 \(\pm\) 51.3 \({}^{\mathrm{a}}\) & 1382.7 \(\pm\) 138.4 \({}^{\mathrm{a}}\) & 1557.2 \(\pm\) 125.4 \({}^{\mathrm{a,b}}\) & 1687.4 \(\pm\) 140.4 \({}^{\mathrm{b}}\) \\ \hline n\({}^{\prime\prime}\) (-) & 0.071 \(\pm\) 0.004 \({}^{\mathrm{a}}\) & 0.114 \(\pm\) 0.003 \({}^{\mathrm{b}}\) & 0.125 \(\pm\) 0.004 \({}^{\mathrm{c}}\) & 0.139 \(\pm\) 0.007 \({}^{\mathrm{d}}\) \\ \hline r\({}^{2}\)\(>\) & 0.858 & 0.938 & 0.940 & 0.939 \\ \hline Tan\(\delta\)TM at 1 Hz & 0.380 \(\pm\) 0.004 \({}^{\mathrm{c}}\) & 0.396 \(\pm\) 0.008 \({}^{\mathrm{d}}\) & 0.344 \(\pm\) 0.007 \({}^{\mathrm{b}}\) & 0.292 \(\pm\) 0.002 \({}^{\mathrm{a}}\) \\ \hline J\({}_{0}\) 10\({}^{4}\) (Pa\({}^{-1}\)) & 3.40 \(\pm\) 0.23 \({}^{\mathrm{b}}\) & 2.96 \(\pm\) 0.17 \({}^{\mathrm{b}}\) & 2.04 \(\pm\) 0.18 \({}^{\mathrm{a}}\) & 1.66 \(\pm\) 0.11 \({}^{\mathrm{a}}\) \\ \hline \(\eta_{0}\) (KPa-s) & 286.1 \(\pm\) 11.5 \({}^{\mathrm{a}}\) & 536.5 \(\pm\) 61.5 \({}^{\mathrm{a}}\) & 1135.1 \(\pm\) 98.5 \({}^{\mathrm{b}}\) & 1751.0 \(\pm\) 107.5 \({}^{\mathrm{c}}\) \\ \hline J\({}_{1}\) 10\({}^{4}\) (Pa\({}^{-1}\)) & 4.55 \(\pm\) 0.21\({}^{\mathrm{c}}\) & 3.69 \(\pm\) 0.31 \({}^{\mathrm{b}}\) & 1.98 \(\pm\) 0.23 \({}^{\mathrm{a}}\) & 1.42 \(\pm\) 0.21 \({}^{\mathrm{a}}\) \\ \hline \(\lambda_{\mathrm{ret}}\) (s) & 71.8 \(\pm\) 0.9 \({}^{\mathrm{a}}\) & 70.7 \(\pm\) 1.7 \({}^{\mathrm{a}}\) & 67.8 \(\pm\) 6.1 \({}^{\mathrm{a}}\) & 64.8 \(\pm\) 5.4 \({}^{\mathrm{a}}\) \\ \hline r\({}^{2}\)\(>\) & 0.991 & 0.993 & 0.994 & 0.995 \\ R (\%) & 65.38 & 75.74 & 76.43 & 88.51 \\ \hline K (Pa-s\({}^{n}\)) & 702.1 \(\pm\) 8.6 \({}^{\mathrm{a}}\) & 428.0 \(\pm\) 28.8 \({}^{\mathrm{b}}\) & 413.7 \(\pm\) 14.8 \({}^{\mathrm{b}}\) & 391.3 \(\pm\) 31.0 \({}^{\mathrm{b}}\) \\ \hline n (-) & 0.312 \(\pm\) 0.009 \({}^{\mathrm{c}}\) & 0.264 \(\pm\) 0.005 \({}^{\mathrm{b}}\) & 0.249 \(\pm\) 0.003 \({}^{\mathrm{a}}\) & 0.257 \(\pm\) 0.011 \({}^{\mathrm{a,b}}\) \\ \hline r\({}^{2}\)\(>\) & 0.996 & 0.995 & 0.996 & 0.994 \\ \hline \end{tabular}
\end{table} 
Table 1: Parameters of the rheological models describing control gluten-free dough and samples with citrus fiber (CF) addition. Flow curves of analyzed dough samples are shown in Figure 3. The results indicate the nonnewtonian, shear-thinning (pseudoplastic) behavior of gluten-free dough, which is in agreement with earlier observations concerning these type of dough systems [4]. The parameters of the power model, used to describe experimental viscosity curves, are presented in Table 1. Replacement of a part of starch with citrus fiber caused a significant decrease in apparent viscosity during flow compared to the control test. The viscosity reduction may be the result of a significant increase in water content in doughs, resulting from the high water absorption of added fiber, which at the same time results in a decrease in the concentration of guar gum and pectin used as structure-forming factors. Its introduction to the dough therefore seems to be beneficial not only from a nutritional point of view, but also in terms of improving the rheological characteristics of the dough. Due to the presence of a highly water-absorbent component, the system shows structure strengthening in the area of small deformations, but, on the other hand, at large deformations easily flows, which facilitates deformations during technological processing, e.g., mixing, transport, forming.