## 3 Results and Discussion
### Peptide Profile of Digesta Depending on LAB Strains and Aging Time  
Meat proteolysis is a very dynamic process, in which processing time and the presence of microorganisms contribute to variability. This is especially true in the case of dry-cured meat products, where the meat proteome may have a different profile and thus exhibit different biological activities. To understand the effect of time (28, 90, 180, 270, and 360 days) and selected LAB strains on the peptide profile, a PCA scoring plot was constructed to explain the variations associated with processing times, identify those peptides that mainly differentiate the samples, and determine the degree of similarities and differences between the peptides. To ensure partial visualization of the data related to the effect of the type of LAB strain used on the formation of peptides in the product at different aging times, the variables were projected on the factor plane (PC-I \(\times\) PC-II), as shown in Figures 1 and 2. Changes in factors calculated in the factor analysis are presented in Tables 1 and 2. For the water-soluble fraction (WSF), the results showed a relationship between the research variant (type of LAB strain used) and the aging time of pork loin. The analysis of factor loadings (Table 1) revealed that the first component (PC-I) included nine most strongly correlated variables, accounting for 37.49% of the total variance. It is worth noting that the most diverse were samples aged for 270 days (BB12, BAUER) and 360 days (LOCK, BB12, BAUER), while the C samples were also variable after 28 days and BB12 and BAUER samples after day 90 of the production (Table 1). Indeed, [PERSON] et al. [31] reported that the dry-cured pork loins with the probiotic LOCK strain had fewer free amino acids and peptides (WSF) compared to the control sample after 2 months of refrigerated storage. During the same period, dry-cured loin samples inoculated with BAUER contained more peptides, while the sample with _Bifidobacterium animals_ ssp. _lactis_ BB-12 contained the smallest number of peptides, compared to the sample lacking starter cultures [32]. [PERSON] et al. [33] also proved that BB12 and BAUER caused changes in the quantitative and qualitative profile of amino acids in dry-cured loins after 9 months, thus confirming their participation in the proteolysis of meat protein components. Comparing this finding with previous reports on the effect of robotic LAB strains in the production of dry-cured loins [17], it can be stated that treatment and storage time can significantly influence the proteolysis index of dry-cured loin (\(p<0.01\)). In that study [17], this index increased gradually during storage, reaching the maximum value in C and LOCK samples after 270 days of storage, and in BAUER and BB12 samples after 360 days. On the other hand, as shown in Figure 1, after 28 days of storage, the effect of LAB strains was more pronounced, which was positively correlated with PC-I, although previous studies showed no significant difference (\(p>0.05\)) in the content of primary amines in WSF between control and inoculated samples on day 28 of the in vitro test [17]. This discrepancy may be explained by the fact that in the present study, no additional proteolysis occurred in the inoculated dry-cured loin compared to the control during the initial storage stage in quantification, but qualitative changes were observed in peptides released from meat proteins under the influence of microbial peptidases. This confirms the variability of the proteome during the production of meat products, which was directly reflected by the results observed after the simulated gastrointestinal digestion process in this study.