# Development of a Mouthwash Using Freeze-Drying Technique: An Optimization Study
## 3 Results and Discussion
### Development and Evaluation of the Cetraria islandica Extract Mouthwash
#### 3.2.2 Evaluation of the Quality of Fit
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Parameter** & **Response** & **R2** & **Q2** & **_p-Value_ & **Lack of Fit** & **F-Value** & **Model Validity** & **Reproducibility** \\ \hline Rigidity 2 mm & Y1 & 0.87 & 0.56 & 0.029 & 0.529 & 6.65 & 0.84 & 0.74 \\ Rigidity 4 mm & Y2 & 0.80 & 0.62 & 0.028 & 0.411 & 5.94 & 0.78 & 0.77 \\ Load at target & Y3 & 0.79 & 0.65 & 0.009 & 0.677 & 8.62 & 0.90 & 0.61 \\ Fracturability & Y4 & 0.94 & 0.72 & 0.001 & 0.721 & 24.43 & 0.92 & 0.86 \\ Isf fracture & Y5 & 0.94 & 0.64 & 0.001 & 0.258 & 22.28 & 0.66 & 0.96 \\ \hline
1 st fracture & Y6 & 0.90 & 0.69 & 0.004 & 0.171 & 13.77 & 0.56 & 0.96 \\ deformation & Y7 & 0.60 & 0.31 & 0.026 & 0.427 & 5.96 & 0.79 & 0.66 \\ Weight loss & Y8 & 0.92 & 0.79 & 0.002 & 0.730 & 13.64 & 0.92 & 0.80 \\ Reconstitution & Y9 & 0.94 & 0.73 & 0.005 & 0.167 & 15.06 & 0.55 & 0.96 \\ Viscosity & Y10 & 0.80 & 0.49 & 0.027 & 0.360 & 6.03 & 0.74 & 0.80 \\ \hline \end{tabular}  
* R2—Percent of the variation of the response explained by the model; Q2—Percent of the variation of the response predicted by the model, F-value—The ratio of the group means and the mean within group variances; Model validity—Validity of the model; Reproducibility—Variation of the response under the identical conditions, compared to the total variation of the response.  
\end{table} 
Table 4: Statistical parameters for ANOVA test and quality of fit. can be reinforced by increasing the amount of filler and for a rigid profound structure, the filler of choice should be mannitol. Mannitol, a compound with the structure-forming ability [23] and sweetening properties, was selected as a bulking agent since it favors efficient freeze-drying and the attainment of elegant matrices [25]. It gave freeze-dried compacts with appropriate strength even without matrix-forming polymers and it showed superior mechanical properties when compared to trehalose, and lower when compared to maltodextrin [26]. Load at target (Y3) values were the lowest for F2 (524.50 g), F1 (1042.50 g), and F6 (1555.00 g), while the other formulations had values over 2000 g, with the highest for F7 sample (3634.00 g). The load at target corresponds to the hardness of the sample and corresponds to the resistance of all cumulated layers of product crushed under the texture probe. As expected, it was positively influenced by mannitol in high ratios and by high loads of MC (Figure 3c). Fracturability is an indirect measure of the brittleness of a product. It is recorded as the first load drop on the texture profile. For the fracturability measurements (Y4), the lowest value was obtained for F2 sample, 151.17 g, the most brittle product, compared to the highest one recorded of 2322.67 for F5. The increasing of the MC ratio (X3) conducted to increased resistance to fractures (Y4) (Figure 3d). As previous studies showed, the MC three-dimensional network constitutes the structure of the product that sustains the attached fillers. The presence of high amounts of polymers reinforces the matrices and increases their elasticity [23], which explains the lower brittleness and the high fracturability values. The other mechanical resistance parameters measured were the mechanical work needed for first fracture (Y5), which showed values within a high range from 1.31 mJ (F2) to 41.68 mJ (F5); the first fracture deformation (Y6), with F5 and F6 having the highest values of 3.57 mm and 4.99 mm; the mean load (Y7) with values of 31.73-1116.27 g, the lowest corresponding to F2 and the highest to F11. As all the texture parameters, F2 was the weakest formulation, the most fragile, porous, and hard to handle, while F5 and F7 were just the opposite. Figure 2: The determination of mechanical characterization responses out of the load vs. distance and load vs. time profiles generated by the texture analysis.