## 4 Discussion  
The effect of lactic acid applied on the surfaces of wild boar carcasses was evident on all the microbial loads, compared with untreated carcasses. Aromatic vinegar showed less effective activity because it exerted effects only 48 h after the treatment in some of the microbial parameters tested (ACC, SC, and LABC). Figure 2: Aerobic colony count (**A**), _Enterobacteriaceae_ count (**B**), psychotrophic colony counts (**C**), _Staphylococcus_ count (**D**), and _Lactobacillus_ count (**E**) on external surfaces of wild boar carcasses sprayed with 2% Lactic acid solution (LA), aromatic vinegar (AV), and untreated (CTR) after 2 and 48 h from the treatments. Different letters on the bars describe statistically different mean values (\(p<0.05\)). The results of the activity of lactic acid solutions against the microorganisms that grow on the carcasses are in line with other authors' findings, even if several factors of those studies differ from the present study and, therefore, only an attempt of comparison could be made: the percentage and temperature of the solution used; the application procedures of the solution on the carcasses (or on the meat); the time and site of sampling; sampling methods; the microorganism investigated; experimentally contaminated samples; and animal species [21; 28; 29]. Lactic acid is active against microbial loads and specific populations of both Gram-negative and Gram-positive bacteria, in vitro and on meat [30; 31]. This outcome has been registered also in the present study, where the application of lactic acid solution affected both EC and SC. The effects of lactic acid on LAB highlighted in this study depend on the specific LAB population and on different factors, such as the concentration of lactic acid and the presence of other organic acids. For instance, [PERSON] et al. (2007) [32] observed higher effects of lactic acid addition to sauces on _L. plantarum_ than on _L. fructorans_, and the growth probability for both strains is related to the buffering capacity of the media after the treatment (pKa 3.8). The reduction in the MLs between CTR and LA samples was higher than 1 Log only for ACC at T48, while it was lower than 1 Log in the other parameters and times tested (Figure 2). The high hygienic level of the carcasses detected in the present study could not allow for an evaluation of higher ML reductions. Similar effects on MLs (ACC and EC) are reported in beef carcasses by [PERSON] et al. (2020) [33] with lactic acid solution up to 4%, even though samples were collected only after 45 min. Nonetheless, there is no consensus on the microbial quantitative reduction values when lactic acid solutions are applied on carcass surfaces. A reduction of 1 Log was recorded at 24 h by [PERSON] et al. [34] in ACC and PCC on beef carcasses using from 2% to 5% LA solution. Reduction values decreased only after 72 h. Moreover, [PERSON] et al. [35] reported a higher efficiency of the treatment on beef carcasses, with a reduction in ACC of up to 3 Log CFU but using a larger amount of a 4% solution of LA (500 mL), while lower effects (mainly \(<\) 1 Log) were reported for coliforms. Residual growth inhibitions were even reported by [PERSON] et al. [36] that could explain the similar level recorded for MLs at T2 and T48. The antimicrobial activity of organic acids can be exerted by different biochemical pathways, even though the specific mechanisms are still not entirely understood [37]. Many authors indicated that organic acids tend to modify the pH of the surface to an unacceptable level for most microorganisms [28]. Some studies showed that lactic acid is more effective than other organic acids probably due to its higher acidity; in fact, it is documented that acids with lower pH values usually have higher antimicrobial efficacy [38; 39]. Week organic acids have a lower pKa value than the pH of the cell cytoplasm, and when the undissociated acid enters into the cell and dissociates, with the release of protons (H+), a consequent reduction in intracellular pH value is produced [33; 40].