# Enhancement of Wheat Flour and Dough Properties by Non-Thermal Plasma Treatment of Wheat Flour
## 3 Results and Discussion
### Effects of Non-Thermal Plasma Treatment Time on Wheat Flour and Dough Properties
#### 3.1.2 Visco-Elastic Properties of Dough  
Changes in the functional properties of doughs produced with untreated and treated wheat flour were tested as a function of flour treatment duration. These properties were determined by rheological measurements, where the dependence of the storage and loss moduli (G\({}^{\prime}\) and G\({}^{\prime\prime}\)) of doughs were plotted against the induced deformation. The modulus G\({}^{\prime}\) represents the elastic properties and the modulus G\({}^{\prime\prime}\) represents the viscous properties of a wheat dough. These two parameters, together with their combination, contribute to the functional properties of wheat dough, defining it as a visco-elastic material. The change in the G\({}^{\prime}\) and G\({}^{\prime\prime}\) values of doughs made from the two flour types (550 and 1050) as a function of deformation and treatment time on a logarithmic scale are presented in Figure 5a,b. A rheological behavior diagram for wheat dough has three parts: (1) a linear visco-elastic region, where the elastic properties prevail. This lies between zero deformation and the deformation at which the yield point (i.e., the end of the elastic behavior and the start of plastic behavior) has been reached. This is the point at which the strain corresponds to a ~5% drop in the storage modulus [58]; (2) a plastic region, where the increasing deformation starts to permanently destroy the dough (or protein-starch) structure and cannot be regained. This is the region between the yield point and the flow point (i.e., the threshold of shear stress, above which solid material will start to flow); and (3) the region above the flow point, where a solid behaves as a liquid, since the deformation potential is so huge that all the forces responsible for holding the material structure are overruled. Figure 5a,b shows that G\({}^{\prime}\) is higher than G\({}^{\prime\prime}\), as is characteristic of visco-elastic materials. The experimental results demonstrate that the changes caused by the NTP treatment of flour, reflected by increases in the G\({}^{\prime}\) and G\({}^{\prime\prime}\) values of the formed dough, initially increased as the treatment time was prolonged. This increase reached its maximum value for the treatment time of 3 min for both flour types, after which the values of G\({}^{\prime}\) and G\({}^{\prime\prime}\) sank. Figure 5a and Table 1 demonstrate that the NTP treatment showed its maximum potential for the type 550 flour, with a two-fold increase in the visco-elastic properties (G\({}^{\prime}\) = 85-130% and G\({}^{\prime\prime}\) = 76-111%) for the treatment duration of 3 min. This finding corresponds to the maximum change in hydration properties of flour with the three minutes treatment, as shown in Figure 4. On the other hand, the moduli of the untreated high-protein flour (type 1050) were already significantly higher compared to those of the flour type 550, i.e., 200-400% for G\({}^{\prime}\) and 200-330% for G\({}^{\prime\prime}\). Thus, the corresponding  
Figure 4: Change in the water-holding (**a**) and water-binding (**b**) capacity of wheat flour (type 550) as a function of NTP treatment time. maximum changes in \(G^{\prime}\) and \(G^{\prime\prime}\) in the plasma-treated samples of type 1050 were low to mild (G\({}^{\prime}\) = 0-28% and G\({}^{\prime\prime}\) = 0-16%) (Figure 5b and Table 1). This finding also confirms the limited enhancement of the hydration properties of the type 1050 flour. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Increase (\%)** & \multicolumn{2}{c}{**1 min**} & \multicolumn{2}{c}{**3 min**} & \multicolumn{2}{c}{**5 min**} \\ \hline
**Flour Type** & **G\({}^{\prime}\) (\%)** & **G\({}^{\prime\prime}\) (\%)** & **G\({}^{\prime}\) (\%)** & **G\({}^{\prime\prime}\) (\%)** & **G\({}^{\prime\prime}\) (\%)** & **G\({}^{\prime\prime}\) (\%)** \\ \hline
**550** & 67–105 & 57–88 & 85–130 & 76–111 & 81–123 & 72–110 \\ \hline
**1050** & 10–17 & 8–19 & 0–28 & 0–16 & 0–8 & 0–5 \\ \hline \hline \end{tabular}
\end{table}