## 3 Results and Discussion
### Evaluation of the Effect on the Viability of S. cerevisiae  
The effect of TW and BMW on the viability of _S. cerevisiae_ yeast was evaluated in bread formulations with and without added salt using the flow cytometry technique. Considering the distinct physicochemical characteristics of each water source, speculation was made about their influence on the fermentation capacity of _S. cerevisiae_ during the leavening process of the studied bread doughs. Thus, after the fermentation process, a portion of each type of dough was collected for subsequent analysis in the flow cytometer.  
After analyzing the graphs obtained by flow cytometry, it was found that the viability of _S. cerevisiae_ cells, that is, the number of live cells, was similar in the five types of bread dough studied (Figures 1 and 2).  
Figure 1: Results of flow cytometry were obtained for the analysis of _S. cerevisiae_ viability after the fermentation process. B_DW—dough with drinking water; B_TW—dough with thermal water; B_BMW—dough with bottled mineral water; B_TWns—dough with thermal water without salt addition; B_BMWs—dough with bottled mineral water without salt addition. Dead or damaged _S. cerevisiae_ cells are in orange, and viable _S. cerevisiae_ cells are in green.  
In the bread dough produced with DW, 74% of _S. cerevisiae_ cells were viable (Figure 2); in the bread dough produced with TW with and without added salt, 76% and 73% of _S. cerevisiae_ cells were alive, respectively (Figure 2). Finally, in the bread dough produced with BMW with and without added salt, it was observed that 65% and 68% of _S. cerevisiae_ cells were alive, respectively (Figure 2). According to studies by [PERSON] and colleagues [66], for _S. cerevisiae_ to reach its optimal growth, the pH of the medium should be between 4 and 7. Thus, in this case, the pH of the different waters used (pH value of 6.80 for TW, 6.10 for BMW, and 6.92 for DW; values obtained at the Water Characterization Laboratory--LCA, AquaValor) did not influence the fermentation process, considering that there are no significant differences in the viability of this yeast in the different bread formulations developed.  
Regarding the chemical compositions of the different waters used in this study (Table 1), the concentration of nitrates is relatively low in all of them, being less than 2.0 mg/L in the tap water, less than 0.30 mg/L in the TW, and less than 0.25 mg/L in BMW. Considering that the presence of nitrates as a nitrogen source is essential for the growth of _S. cerevisiae_, the authors [67] studied the effect of increasing concentrations of this compound (16.5 to 805 mg/L) on the multiplication of that yeast, concluding that higher nitrogen concentrations lead to higher biomass production. However, this was not observed in this study, probably due to the minimal differences observed between the nitrate concentrations present in the tested waters, as well as in the tested waters and their low levels. On the other hand, in a study by [PERSON] and collaborators [68], it was found that the presence of K and Na in the culture medium increased the growth of _S. cerevisiae_. However, concerning the types of bread developed in this work, it seems that the observed differences in the chemical compositions of the waters used in terms of K and Na did not affect the viability of _S. cerevisiae_ (Table 1, Figure 2).