# 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
#### 3.1.3 Wheat Dough Microstructure  
[PERSON] et al. [63] studied dough development with light and transmission electron microscopy and revealed that starch granules in dough are usually bigger particles, having an average size of 10-20 \(\upmu\)m, while the protein components are in the form of sheets and fibrils which surround the starch particles. The gluten (protein) network structure is affected by gluten quantity, quality and the number of intermolecular disulphide bonds. Similar SEM analyses of starch and protein structures can be found in the literature [63; 52; 64].  
The SEM images of doughs with untreated and treated (1, 3 and 5 min treatment time) flours (type 550) are shown in Figure 6. As claimed above, proteins create a smooth structure that surrounds the round starch particles. Further, two classes of starch granules can be noticed which differ with respect to their average diameters. It has been reported that type A starch granules (with a flattened shape and about 25 microns in diameter) contribute to malting yield, while type B granules (spherical in shape and about 6 microns in diameter) are responsible for water absorption due to their large surface-to-volume ratios [65].  
In the case of the control sample (Figure 6a), the gluten matrix was non-homogeneous, i.e., it was a discontinuous network in which large and small fragments of gluten could be observed (indicated by arrows). Starch granules are covered with thin gluten layers. However, the starch granules were not fully embedded in the protein matrix, which corresponds to the findings of [PERSON] et al. [66; 67]. In comparison to that prepared with untreated flour, the SEM images of the dough prepared with plasma-treated flour (Figure 6a,b) showed a well-developed gluten matrix network in which starch particles were uniformly embedded, i.e., a well-developed gluten matrix could be observed. This resulted in a stronger dough, consistent with the rheological analysis presented in Figure 5.  
The SEM images for increased treatment times showed only minor differences in the developed gluten network characteristics. However, when the treatment time was equal to 5 min, damage to starch granules was observed (Figure 6a,b), which led to the weakening of gluten networks. This negatively affects the storage and loss moduli of wheat dough [68; 69], as confirmed by the results presented in Figure 5.  
Comparison of the results presented in Figures 5 and 6 indicated an optimal plasma treatment time of 3 min to enhance dough rheological properties. If this time is exceeded, negative effects might occur as a result of the NTP treatment, leading to the weakening of dough networks.  
SEM images for type 1050 samples are visually similar with respect to gluten and protein particles. However, no significant differences between the developed gluten networks of the NTP-treated samples were observed.  
Figure 6: SEM Images of the wheat dough samples prepared with untreated and plasma-treated (1 min, 3 min, 5 min) flour under (**a**) low and (**b**) high magnifications (corresponding to 1000\(\times\) and 2000\(\times\) magnifications in the current SEM set-up). White arrows—gluten network; yellow arrows—changes to starch particles.