## 2 Results
### Microbiological Parameters in Inoculated Samples
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{4}{c}{_Staphylococcus aureus_} & \multicolumn{4}{c}{_Salmonella Typhimurium_} & \multicolumn{4}{c}{_Listeria monocytogenes_} \\ \hline \multicolumn{4}{c}{**(Log MPN/mL or g)**} & \multicolumn{4}{c}{**(Log MPN/mL or g)**} & \multicolumn{4}{c}{**(Log MPN/mL or g)**} \\ \hline \multicolumn{4}{c}{**Milk**} \\
**Inoculum** & \multicolumn{4}{c}{**7.3**} & \multicolumn{4}{c}{**7.2**} & \multicolumn{4}{c}{**7.3**} \\ \hline
**Cheese** & **Surface** & **Main Matrix** & **Core** & **Surface** & **Main Matrix** & **Core** & **Surface** & **Main Matrix** & **Core** \\ \hline
24 h & & 8.7 & & & 4.8 & & & 8.7 & \\
7 d & 6.7 \({}^{\text{a}}\) & 6.42 \({}^{\text{b}}\) & 5.45 \({}^{\text{b}}\) & 3.55 \({}^{\text{A}}\) & 2.82 \({}^{\text{B}}\) & 3 \({}^{\text{B}}\) & 7.4 \({}^{\text{a}}\) & 7.4 \({}^{\text{b}}\) & 6.9 \({}^{\text{b}}\) \\
15 d & 7.2 \({}^{\text{a}}\) & 3.77 \({}^{\text{b}}\) & 5.05 \({}^{\text{b}}\) & 3.85 \({}^{\text{A}}\) & 2.4 \({}^{\text{B}}\) & 4 \({}^{\text{B}}\) & 7.1 \({}^{\text{a}}\) & 5.6 \({}^{\text{b}}\) & 5.3 \({}^{\text{b}}\) \\
30 d & 6.4 \({}^{\text{a}}\) & ND & 1.8 \({}^{\text{b}}\) & 4.51 \({}^{\text{A}}\) & 0.67 \({}^{\text{B}}\) & 3.6 \({}^{\text{B}}\) & 6.1 \({}^{\text{a}}\) & ND & ND \\
45 d & 5.3 \({}^{\text{a}}\) & ND & 0.15 & 1.85 \({}^{\text{A}}\) & 0.72 \({}^{\text{B}}\) & ND & 4.5 \({}^{\text{a}}\) & ND & ND \\
60 d & 4.7 \({}^{\text{a}}\) & ND & ND & ND & ND & ND & ND & ND \\
75 d & 4 \({}^{\text{a}}\) & ND & ND & ND & ND & ND & ND & ND \\
90 d & 3.6 \({}^{\text{a}}\) & ND & ND & ND & ND & ND & ND & ND \\ \hline \multicolumn{4}{c}{d = days of maturation; ND = not detected. Values with different superscripts (\({}^{\text{a}}\) or \({}^{\text{A}}\),B) in the rows, are significantly different between adjacent columns of the same pathogen (_p_ < 0.05).} \\ \end{tabular}
\end{table} 
Table 2: Behavior of pathogens in Cotija cheese made with inoculated milk. they (\(p>0.05\)). Only the AMB had a higher content in milk and cheese (\(p<0.05\)). The four types of samples showed \(<\)10 Log CFU/ g or mL of molds and yeasts (Figure 2). The indicator groups in cheese showed that after seven days of maturation, LAB continued to show a homogeneous behavior in the microbial content of the different areas analyzed (core, main matrix, and surface) and between the non-inoculated and inoculated cheese. In non-inoculated cheese, indicator groups maintained an average of around 9.0 log of CFU/g until day 45, then decreased to 1 log CFU/g from day 60, maintaining those count values until the end of this work. In the inoculated Cotija cheese, the LAB behavior was similar. However, it was maintained with an 8.8 log CFU/g until the end of the study. The statistical analysis showed a significant difference between the main matrix and the core in the indicator groups at 15, 75 and 90 days (\(p<0.05\)). There was no difference in either of the two groups, inoculated and not inoculated (\(p>0.05\)). From cheeses with seven days of maturation, main matrix and surface samples from days 7 and 15 had the highest content of indicator groups with an average of 5.9 and 6.4 log of CFU/g, respectively, while the core had 5.0 log of CFU/g. After 30 days, a gradual decrease in the microbial load was observed, more critical in the main matrix and the core. At 90 days, the AMB content was 2.4 log CFU/g in the core, 2.2 log CFU/g in the main matrix and 3.4 log CFU/g in the surface. Statistically, there was a difference in the AMB content in the surface regarding the main matrix and the core on days 7, 30, 45, 60, \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Lactic Acid Bacteria**} & \multicolumn{2}{c}{**Aerobic Mesophilic Bacteria**} & \multirow{2}{*}{**Coliforms**} & \multirow{2}{*}{**Molds and Yeast**} \\  & & & & \\ \hline Milk * & 9.1  & 6.5  \\ Curd ** & 9.4  & 6.1  \\ Whey * & 8.9  & 5.8  \\ Cheese ** & 7.2  & 7.2  \\ \hline \hline \end{tabular}
\end{table}