## 3 Results and Discussion
### Cooking Properties  
The incorporation of various amounts of SPI into high-gluten wheat flour noodles significantly changed the cooking properties (Table 2). The moisture of raw noodles increased with the increasing replacement rate of SPI. Increasing the SPI content to 10% caused a significant difference in the moisture content of SPI noodles and control noodles. [PERSON] et al. found that the incorporation of soy flour into soup powder increased the water absorption capacity of the soup powder [37]. SPI has high water-holding capacity, water retention, and expansion, and is therefore widely used in the food industry as a gelling agent [38]. The high water-absorption capability of SPI noodles might be due to their high protein content, which encourages the formation of hydrogen bonds between the water molecules and the polar groups on the polypeptide chains. Therefore, the moisture content of raw noodles increased with the increase in SPI content due to the water absorption of SPI during cooking. Similar to our results, an increase in moisture content was reported \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & **Moisture** & **Crude Protein** & **Lipid** & **Ash** & **Carbohydrate (\%)** \\  & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** \\ \hline SPI powder & 13.39 \(\pm\) 0.01 d & 78.54 \(\pm\) 1.45 a & 0.27 \(\pm\) 0.04 a & 4.59 \(\pm\) 0.04 a & 3.24 \(\pm\) 1.45 f \\ Noodles (control) & 36.06 \(\pm\) 0.02 c & 16.17 \(\pm\) 0.46 f & 0.31 \(\pm\) 0.07 a & 0.43 \(\pm\) 0.06 e & 47.05 \(\pm\) 2.43 a \\
5\% SPI noodles & 37.67 \(\pm\) 0.00 bc & 19.83 \(\pm\) 0.82 e & 0.30 \(\pm\) 0.01 a & 0.90 \(\pm\) 0.00 d & 41.05 \(\pm\) 1.05 b \\
10\% SPI noodles & 39.18 \(\pm\) 0.01 b & 23.17 \(\pm\) 0.41 d & 0.26 \(\pm\) 0.06 a & 1.07 \(\pm\) 0.01 d & 35.97 \(\pm\) 0.04 c \\
15\% SPI noodles & 43.36 \(\pm\) 0.01 a & 27.06 \(\pm\) 0.83 c & 0.28 \(\pm\) 0.04 a & 1.28 \(\pm\) 0.04 c & 27.52 \(\pm\) 0.65 d \\
20\% SPI noodles & 44.84 \(\pm\) 0.01 a & 30.69 \(\pm\) 0.32 b & 0.26 \(\pm\) 0.04 a & 1.50 \(\pm\) 0.18 b & 23.06 \(\pm\) 0.80 e \\ \hline \hline \end{tabular}  
* The Tukey–Kramer HSD test was applied to compare means for all pairs. Data are expressed as mean \(\pm\) SD (n = 3). Means followed by different letters are significantly different at \(p\) < 0.05.  
\end{table} 
Table 1: Proximate composition of SPI powder, noodles and SPI noodles. for SPI-supplemented whole-grain flat rice noodles (64.98%) compared to control noodles (59.78%) [39]. The cooking yield of noodles is listed in Table 2. The cooking yield is an important indicator of noodle quality, which is mainly contributed by starch gelatinization and water absorption by protein. The cooking yield of 5%, 10%, 15%, and 20% SPI noodles was 1.45, 1.50, 1.52, and 1.65%, respectively. A higher SPI content resulted in a higher cooking yield compared to control noodles. Since SPI had high water-holding ability, the cooking yield of SPI noodles increased during cooking indicating a positive correlation between water absorption and cooking yield in this case [29; 40]. This is because of the presence of many polar groups on the backbone of SPI, resulting in water retention and swelling of the noodles. The water absorption of wheat flour spaghetti has been reported to increase significantly as the gluten level increased [41]. On the other hand, the cooking loss of 5%, 10%, 15%, and 20% SPI noodles was 0.89, 1.25, 1.44, and 1.61%, respectively. The SPI noodles showed higher cooking loss than the control noodles. Gluten protein is responsible for maintaining the structural integrity of noodles [42]. During the cooking of noodles, the gluten network structure can prevent the carbohydrate from leaching into the water. Reduced gluten leads to a weaker structure, which allows more noodle content to dissolve into the cooking water, thus increasing cooking loss [40; 43]. The results of the present study were in line with those of other reported studies.