## 3 Results and Discussion
The values registered in this study are remarkably higher than the value obtained through the growth  
Figure 2: Growth curves of _L. monocytogenes_ fitted by the DMFFit program according to the Baranyi and Roberts model [38] for three different batches of spreadable salami experimentally contaminated. prediction performed with the Combase Predictor tool [42] that was of 0.72 days (17.3 h, data not shown). As reported in the literature, the duration of the latency phase is characterized by inherent variability and by partially defined physiological and molecular processes [43], however, recent findings suggest that changes in the lag-time in order to develop tolerance can be considered the first change made by bacteria in response to stressor factors [44]. The optimization and elongation of Lag may therefore represent a strategy adopted by bacterial communities to tolerate environmental stress [43; 44; 45], that may correspond, in this study, to the hurdles present in the food matrix. These results demonstrate the inhibitory effect of the process and the product characteristics on _L. monocytogenes_ growth, even though the studied spreadable salami showed a pH and a\({}_{\text{w}}\) values compatible with the growth of the microorganism [28]. In fact, similarly to what has been reported by other authors, the physicochemical properties of spreadable salami are not sufficient to justify the pathogen behavior [41], indeed, it has already been highlighted that _L. monocytogenes_ is able to survive in environments with pH and a\({}_{\text{w}}\) values lower than those found in this study [46]. The factors that could affect the behavior of _L. monocytogenes_ in RTE meat products are numerous, such as reductions in pH [47] and a\({}_{\text{w}}\)[48], the use of additives [49], and the presence of indigenous microflora [50]. The presence of NaCl is considered a method to control the pathogen growth, however, the concentration used in the present experiment is not demonstrated to limit _L. monocytogenes_ growth [51]. Similarly, the temperature applied during the ripening phase and the storage period could not have negatively influenced the growth capacity of _L. monocytogenes_ since the strains used for experimental contamination had undergone a process of thermal adaptation. The main hurdle in _L. monocytogenes_ growth, as shown in the literature, is probably represented by lactic acid flora [50]. Several studies have shown, in fact, that the presence of LAB in foods can hinder the growth of pathogens by means of competition for nutrients, antimicrobial metabolite production and more generally through microbial antagonism [52; 53]. Specifically, as reported in the literature, the reduction in _L. monocytogenes_ count in some foodstuffs may have been attributable to the inhibitory effects of various metabolic products of LAB such as carbon dioxide, short-chain organic acids, hydrogen peroxide, diacetyl, and antimicrobial peptides [54]. The inhibitory activity of LAB towards sensitive food spoilage or pathogenic bacteria, such as _L. monocytogenes_, has been reported for various food products [52; 55; 56]. Particularly, [PERSON] et al. [57] and [PERSON] et al. [58] state that the lactic flora present in fermented products, such as salami, exerts a remarkable inhibitory effect on _L. monocytogenes_ growth especially when the aforementioned microflora is present in concentrations higher than 4.5 Log CFU/g by creating an unfavorable environmental condition for the pathogen. Studies of the LAB population of spreadable salami produced in Central Italy revealed that the most frequently detected lactic species were _Lactobacillus sakei_, _Lactobacillus plantarum_, _Lactobacillus curvatus_ and _Pediococcus pentosaceus_[25; 40; 59; 60]. Some authors claim that the anti-literial potential of bacteriocin _L. sakei_ and _L. curvatus_ represents an efficient tool to counteract the development of pathogens such as _L. monocytogenes_ in food, even at low temperatures [61; 62; 63; 64].