# The Effect of Inulin Addition on Rice Dough and Bread Characteristics
## 3 Results and Discussion  
### The Effect of Inulin on Dough Characteristics  
The addition of inulin had a notable impact on the dough behavior during uniaxial elongation tests. The presence of inulin weakened the rice dough, which is evident from the significant decrease in the dough's resistance to elongation (\(R_{m}\)) recorded in the samples with added inulin (Table 1). The weakening effect of the added inulin was also apparent in the values of the _Area_ parameter, which relates to the energy required for dough deformation. The samples with added inulin required less energy for deformation (306-683 mN mm) than the samples made from pure rice flour (704 mN mm).  
Conversely, the added inulin had the opposite effect on the wheat dough with 2-8% added inulin [33; 34]. These results were explained by the interaction between inulin and gluten. The proteins in rice flour have a lower molecular weight than those in gluten, and they also differ in chemical composition [18], which may account for our observations. Inulin competed with starch for water in the dough and reduced the available water for starch hydration. Therefore, inulin's water binding ability was probably a key factor in modifying the dough properties [35], and this likely negated the differences between the samples with added inulin.  
Extensibility \(E\) is another parameter that was recorded during the uniaxial elongation tests. The values of extensibility rose with the increasing amount of inulin and, after reaching a maximal extensibility in a sample with 20% inulin, the extensibility started to decrease. The differences between samples (5-30% inulin) were, however, not significant. The presence of inulin increased the polymerization of proteins present in the rice flour [33], which improved the doughs' ability to elongate. The 40% added inulin was probably higher than optimal, resulting in a negative impact on the dough characteristics. Since gluten-free doughs generally exhibit an insufficient ability to elongate and trap leavening gas, which is crucial for obtaining bread with the desired volume [36], the addition of up to 30% of inulin seems to be optimal to prepare dough with improved elongational characteristics.  
The weakening effect of inulin on rice dough was also recorded during the heating tests (Figure 1). The complex viscosity \(\eta^{\star}\) at the beginning of the heating tests was decreased by the presence of 10%, 20%, 30%, and 40% inulin. The thermally induced changes recorded in the dough with 5% added inulin was close to the dough prepared from pure rice flour. The presence of higher amounts of inulin (10-40%) resulted in a shift of the temperature of starch gelatinization toward higher values. This effect rose with a rising amount of inulin. Inulin is known to take part in the competition for water and may bind a part of water during dough mixing. Furthermore, the viscosity of an inulin solution is quite low [9], which may account for the decrease in complex viscosity observed in the samples containing inulin. When water was released from proteins denatured by temperature, inulin bound to a portion of this water, thereby reducing the dough viscosity. Furthermore, due to its hydrophilic nature, inulin competed with starch for the water necessary for starch gelatinization, resulting in an increase in the gelatinization temperature [37; 38; 39].  
\begin{table} \begin{