## 4 Discussion
[13], the interaction between selected starter cultures and environmental conditions drives the cell metabolisms towards results that can be beneficial or detrimental for the quality of the meat products. According to [PERSON] et al. [40], [PERSON] and [PERSON] [38], [PERSON] et al. [22], and also [PERSON] et al. [17], it is clear that adding LAB starter cultures to meat not only provides new sensory properties and health benefits but also ensures greater product safety and stability. In contrast, probiotic starter cultures, as a result of their metabolic transformations, produce several bacteriostatic and bactericidal substances (e.g., lactic, acetic, formic acid, ethanol, or bacteriocin), thus inhibiting the development of spoiling and pathogenic microflora, including Gram-negative strains belonging to the family _Enterobacteriaceae_ and _Pseudomonaceae_ and such species as _Listeria monocytogenes_ or _Staphylococcus aureus_; thereby naturally preserving dry fermented meat products [2; 8; 41; 42; 43]. The addition of the probiotic starter culture LOCK900 and their bio-conservation effect improved the physicochemical stability of the study meat products. Through their metabolic transformations, LAB produces, among others, lactic acid, thereby reducing the pH of the finished meat product [43]. The low pH value was observed in fermented probiotic sausages (4.90, 4.69, 4.66, respectively), which also had a high LAB number (8.08, 8.30, 8.21 log CFU g\({}^{-1}\), respectively). The increase in acidity during fermentation and maturation affects the coagulation of muscle proteins, resulting in increased firmness and consistency of end products and the formation of a red color and characteristic taste [14; 19; 44; 45]. The rapid decrease in pH contributes to inhibiting the development of adverse microflora and preventing the accumulation of biogenic amines [4; 46]. The pH values of the inoculated sausages were lower than the pork loin after fermentation because the initial LAB inoculation led to a higher accumulation of lactic acid during ripening and consequently lowered the pH [40]. This indicated that the inoculation of probiotic cultures prompted carbohydrate breakdown and the accumulation of organic acids, mainly lactic acids, which led to a significantly faster acidification rate of the sausages than in the joins, which mirrored the reports by [PERSON] et al. [22] and [PERSON] et al. [47]. The number of lactic acid bacteria in the product, and thus its pH value, indicates the evolution of the fermentation. The probiotic strain _L. rhamns_ LOCK900 used for fermenting the loin and pork sausage produces significant amounts of organic acids modifying the pH of the meat product. A similar relationship has been observed by [PERSON] et al. [20] during the production of dry fermented neck with the same starter probiotic culture LOCK900 with the addition of grape seed extract. The authors observed that the addition of probiotic culture to the neck matrix increased the acidity of the product during storage. The increase in the acidity of the products during refrigerated storage suggests that the addition of a probiotic had a beneficial effect on the fermentation process. Lower pH values in the probiotic loin compared to the control loin, which underwent spontaneous fermentation, showed that the probiotic strain used probably improved the fermentation process by producing more organic acids, especially lactic acid. These results correspond with the findings of other authors who confirmed the effectiveness of the inoculation with LAB for the acidification of dry-cured meat products [22; 48]. [PERSON] et al. [17] observed similar results in their studies in fermented camel sausage. The increase in pH values in the probiotic sausages after 6 weeks could be due to an increase in proteolytic peptides and amino acid and amines which have buffering effects on organic acids, which was induced by bacterial proteases [49] or decreases in the number of LAB [50].