# Features of Bread Made from Different Amaranth Flour Fractions Partially Substituting Wheat Flour
## 3 Results
### Four Chemical Characteristics
The quadratic regression model was fitted for the dough strength, which indicates that this alveograph parameter was significantly (\(p<0.05\)) influenced by the linear and quadratic term of the AF addition level. It can be observed in Figure 3c that when the AF amount increased, the dough strength decreased. The alveograph configuration ratio presented a significant (\(p<0.05\)) increase only with AF addition level increase (Figure 3d). Figure 1: Three-dimensional response surface plots showing the interaction between amaranth flour particle size and addition level on (**a**) the Falling Number index (FN), (**b**) water absorption (WA), (**c**) development time (DT), and the (**d**) dough stability (ST) achieved during mixing. Figure 3: Three-dimensional response surface plots showing the interaction between amaranth flour particle size and addition level on: (**a**) dough tenacity (P); (**b**) dough extensibility (L); (**c**) dough strength (W); and (**d**) alveolar configuration ratio (P/L). Figure 2: Three-dimensional response surface plots showing the interaction between amaranth flour particle size and addition level on: (**a**) protein weakening (C1-2; (**b**) starch gelatinization (C3-2); (**c**) the stability of hot starch gel (C3-4); and (**d**) starch retrogradation (C5-4). Influence of Particle Size and Addition Level of Amaranth Flour in Wheat Flour on Dough Fermentation, Dynamic Rheological Properties, and Bread Characteristics  
The quadratic model successfully fitted (\(p<0.05\)) the data for the maximum height of the gas release curve (H'm), the volume of gas retained in the dough at the end of the test (VR), the retention coefficient (CR), elastic modulus (G'), loss tangent (tan \(\delta\)), maximum gelatinization temperature (T\({}_{\text{max}}\)), maximum creep compliance (J\({}_{\text{cmax}}\)), maximum recovery compliance (J\({}_{\text{max}}\)), bread volume (BV), and bread firmness (BF). The variations were explained in proportions of 66 to 92% (Table 4). For total CO\({}_{2}\) volume production (VT) and viscous modulus (G\({}^{\prime\prime}\)) data prediction, the 2 FI model was found to be adequate (\(p<0.05\)), with an explained variation of 70 and 71%, respectively (Table 4). Table 4 shows the effects of PS and AF addition formulation factors on the maximum height of the gas release curve (H'm). The regression model indicates that the linear term of the addition level had a significant (\(p<0.05\)) influence on the H'm parameter, while the PS had a non-significant effect (\(p>0.05\)). A response surface plot, showing the effect of AF level and PS on H'm, is represented in Figure 4a, and it can be seen that the H'm significantly increased as the AF level increased. The effect of the particle size and AF addition level on the total CO\({}_{2}\) volume production of amaranth-wheat composite flour dough as their corresponding regression coefficients in the 2 FI model indicated is presented in Table 4. The VT varied from 1123 mL to 1421 mL, which was lower compared to the wheat control (1168 mL), but an increase in VT can be observed with the increase of AF addition, while the PS had no significant (\(p>0.05\)) influence (Figure 4b). The volume of the gas retained in the dough at the end of the test (VR) was influenced significantly (\(p<0.05\)) by the linear term of the AF addition level and the quadratic term of this factor (Table 4). The regression model for the VR (Table 4) showed a non-significant (\(p>0.05\)) effect in linear terms of particle size and in terms of the interaction between particle size and AF addition level. The AF addition level positively affects VR, while the quadratic term of the AF addition level negatively influences it (Figure 4c). The effect of the PS and AF level on the CR, expressed as their corresponding regression coefficients in the quadratic regression model, is shown in Table 4. The CR was significantly influenced (\(p<0.05\)) by the quadratic term of the AF level in a negative way.