## 3 Results and Discussion
### Optimization of Parameters and Validation of the Models  
Small particle size (200 \(\upmu\)m in this study) did not give significant differences in the cohesiveness, with the linear term having the most significant influence in Equation (3) (\(p<0.01\)). Multiple regression analysis was used to analyze the experimental data, and thus a quadratic polynomial equation was obtained as follows (*** \(p<0.001\); *** \(p<0.01\); * \(p<0.05\)). A small decrease in cohesiveness with spent grain addition level increase was observed in Figure 1A. Cohesiveness is the ability of the material to withstand two successive compressions [41]. [PERSON] et al. (2010) showed in their study that the addition of flour to pasta with vegetables had no impact on cohesiveness [41]. \[\text{Cohesiveness}=0.289-0.021\text{A}^{***}+0.008\text{A}^{2} \tag{3}\]  
Firmness represents the cutting force required to penetrate pasta dough and was significantly increased by the linear term in Equation (4). The shaping of the pasta is influenced by the firmness of the dough, with a stronger dough desirable for shaping the short pasta to keep its shape [42; 43]. A rise in firmness with an increase in spent grain addition level was observed (Figure 1B). [PERSON] et al. reported that a pasta enriched with legume flour (navy bean, pinto bean, lentil, and green pea) or protein concentrates caused \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Chematical Composition** & **Spent Grain Flour** & **Spelt flour** \\ \hline lipids & 7.11 \(\pm\) 0.39 & 3 \(\pm\) 0.01 \\ fiber & 22.67 \(\pm\) 0.42 & 8 \(\pm\) 0.05 \\ protein & 18.88 \(\pm\) 0.37 & 14 \(\pm\) 0.09 \\ ash & 3.47 \(\pm\) 0.02 & 2.11 \(\pm\) 0.04 \\ moisture & 5.04 \(\pm\) 0.42 & 11.26 \(\pm\) 0.08 \\ \hline \hline \end{tabular} Results are expressed as g reported at 100 g dry matter.  
\end{table} 
Table 1: Chemical composition of spent grain flour and spelt flour [39]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Response** & **Model** & **F-Value** & **\(p\)-Value** & **R\({}^{2}\)** & **Adj-R\({}^{2}\)** \\ \hline Cohesiveness & quadratic & 14.6 & \textless{}0.01 & 0.87 & 0.81 \\ Firmness & linear & 100.76 & \textless{}0.01 & 0.95 & 0.94 \\ Color & linear & 15.18 & \textless{}0.01 & 0.75 & 0.70 \\ Fracturability & quadratic & 105.81 & \textless{}0.01 & 0.98 & 0.97 \\ Crude proteins & quadratic & 415.93 & \textless{}0.01 & 0.99 & 0.99 \\ Total dietary fiber & linear & 247.60 & \textless{}0.01 & 0.98 & 0.97 \\ Total phenolic content & linear & 364.43 & \textless{}0.01 & 0.98 & 0.98 \\ Antioxidant activity & quadratic & 63.25 & \textless{}0.01 & 0.96 & 0.95 \\ Cooking loss & quadratic & 253.08 & \textless{}0.01 & 0.99 & 0.98 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: ANOVA results for spent grain pasta and dough. an increase in pasta firmness [44]. [PERSON] et al. showed that an increase in bean flour levels resulted in a slight increase in pasta dough firmness [45]. \[\text{Firmness = 5861.87 + 533.081A***} \tag{4}\]  
The first factor governing food acceptability is the product appearance; in the case of spent grain incorporation, the color of the products is darker with increased incorporation. The same results were observed in other studies [34; 46; 47; 48]. Products with high fiber  
Figure 1: Effect of spent grain on **(A)** dough cohesiveness, **(B)** firmness of pasta dough, **(C)** pasta color, (**D**) pasta fracturability, **(E)** protein content, **(F)** total dietary fiber content, (**G**) total phenolic content, (**H**) antioxidant activity of pasta, and **(I)** pasta cooking loss. contents have a positive feature of dark coloring, which consumers associate with products rich in fiber [34]. Pasta color was affected by spent grain incorporation; a significant increase in C* was observed with the additional level increase. The linear term had the greatest significant influence, as can be seen in Equation (5). Figure 1C shows the increase of color with spent grain addition.