## 4 Discussion  
In the present work, the viable microbial population of different dough samples collected during the production process of Panettone was assessed. The sourdough MA showed a strong dominance of _K. humilis_ species, with only one sample identified as a group-species _K. humilis/K. parahumilis_. This homogeneous result was already observed in traditional sourdoughs [8; 10; 13; 47]. In sourdough MB, four sequenced strains belonged to the _S. cerevisiae_ species, while the other strains belonged to the _K. humilis_ species. The interactions of these two yeast species were also usually found in several traditional sourdoughs [8; 48; 49]. In our case, the minor number of refreshments of MB sample and the reduced fermentation step probably could have favored the dominance of _S. cerevisiae_, thanks to its rapid metabolism and growth rate. Concerning LAB, the results showed the prevalence of heterofermattative-obliged bacteria, with the exception of _Lacp. plantarum_, which is a facultative heterofermattative bacterium, normally colonizing sourdoughs characterized by continuous back-slopping and low incubation temperature [3]. _Fl. sanfranicsensis_ was found in both sourdoughs with a major occurrence in the A samples. Strains of this species are commonly reported as the main components of sourdoughs due to their ability to adapt to the highly selective conditions of this environment [4; 6; 18; 49]. Moreover, _Fl. sanfranicsensis_ strains utilize preferentially maltose and are generally unable to ferment fructose; therefore, there is a non-competitive association of this species with other different LABs. For instance, a stable association is reported between _Fl. sanfranicsensis_ and _Lacp. Plantarum_, as the latter species  
Figure 8: Correlation plot among discovered VOCs and isolated species, obtained using R package Corrplot and Pearson’s correlation index. The positive and negative correlation were considered based on \(\mathrm{R}^{2}\geq 0.6\) and \(\mathrm{R}^{2}\leq-0.6\), respectively. preferentially fermions glucose and fructose rather than maltose, whose metabolism is subject to carbon catabolite repression [3; 50; 51]. Regarding maltose utilization, another stable association is described between _Fl. sanfranciscensis_ and maltose-negative yeasts such as _K. humilis_. On the other hand, the interactions of _Fl. sanfranciscensis_ and _S. cerevisiae_ are reported to be strain-specific and evidently competitive [52]. Regarding _Furl_. _Rossiae_, its presence in both sourdough samples is quite interesting. This species was described by [PERSON] et al. [53] and subsequently studied for its fermentative properties by [PERSON] et al. [54]. _Furl_. _Rossiae_ was found in both samples A and B, mostly in association with other LAB species, as shown in IMPA. The species _Leuc_. _Citreum_ and _Leuc_. _Mesetteoides_, which were also found in both dough types, are typical of the last stages of the Panettone process [18]. Their presence, along with _Lacp_. _Plantarum_, _Furl_. _Rossiae_, and _Fl. Sanfranciscensis_, could be explained by the low temperature of the process [3]. The occurrence of _Lacp. plantarum_ in sourdough is also widely described as a both sub-dominant and dominant species [18; 55]. Less common but explainable is the presence of _Lenl. parabuchneri_, a species commonly found in beer and dairy products [55]. Concerning the VOCs detected and their correlation to the yeasts and LAB species found in the samples, the contribution of the microbial activity to the production of the different metabolites was evident. Noteworthy are the VOCs belonging to the alcohols group. Ethanol, isoamyl alcohol, and phenethyl alcohol were much higher in MB compared to MA and, even though their amount in IMP and FIN samples decreased because of a dilution effect (due to addition of ingredients), they kept higher concentrations in the different stages of method B, with a final difference by around 37% between the two methods. This result may be ascribed to the presence of _S. cerevisiae_ in the B samples.