## 3 Results and Discussions
and at the end of storage, they ranged from 3.99 (PFVB4) and 3.70 (PFVB2). Therefore, and taking into account the average pH value of all PFVBs at the beginning (3.91 \(\pm\) 0.14) and end (3.82 \(\pm\) 0.12) of storage, it can be concluded that no significant differences were observed between both sampling points. In this sense, the low pH values obtained, combined with the cold storage temperatures (4 \({}^{\circ}\)C), were significant environmental factors able to control microbial growth. Most familiar pathogenic or spoilage bacteria, like _Enterobacteriaceae_, _Staphylococci_, _Listeria_, and _Salmonella_ spp., are neutrophles and do not fare well at acidic pH. Also, fungi were also not noticed in the PFVBs, which may be due to the use of potassium sorbate during storage. This preservative has proved to be very effective in controlling yeast growth at acidic pH [43]. However, all of these environmental factors (low temperature and pH values, the use of preservatives, the presence of antimicrobial compounds such as polyphenols, etc.) could also negatively affect the viability of probiotictic cells during storage. The PFVBs were fortified with a theoretical value of the probiotictic _L. pentosus_ LPG1 of 7.12 log\({}_{10}\) CFU/mL (13.3 mill CFU/mL). As can be deduced from Table 2 and using the counts obtained in the LAB medium, within the first 3 days, the probiotictic decreased their population levels in the different types of juices studied. The greatest decline was observed for the sample PFVB3 elaborated with apple and red fruit juice principally, which reached 5.92 log\({}_{10}\) CFU/mL. The remaining formulations reached values close to 6.5 log\({}_{10}\) CFU/mL. This value was kept constant throughout storage, and after 52 days of storage, the average probiotictic counts obtained were 6.45 log\({}_{10}\) CFU/mL (>3.4 mill CFU/mL), with a survival rate of 25.6%. The highest count at 52 days was obtained for the PFVB3 juice with 6.66 log\({}_{10}\) CFU/mL. In this sense, different authors [44; 45; 46] point out that for maximum health benefits, the minimum probiotictic organism level in probiotic food products should be 10\({}^{6}\)-10\({}^{7}\) CFU/mL at the time of consumption. To confirm that the LAB counts obtained in the different types of PFVBs correspond to the probiotictic _L. pentosus_ LPG1, three isolates randomly taken from the LAB medium for each juice were molecularly compared with the rep-PCR profile of _L. pentosus_ LPG1. As can be deduced from Figure 1, the 12 isolates' rep-PCR profiles were identical to the LPG1 control, confirming the presence of the probiotictic at 52 days of storage. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Juice Code** & **Time** & **pH** & **LAB** & **Yea** & **Ent** & **Lis** & **Sal** & **Sta** \\ \hline \multirow{2}{*}{PFVB1} & Initial & 3.90 \(\pm\) 0.11 & 6.53 & Nd * & Nd & Nd & Nd & Nd \\  & Final & 3.78 \(\pm\) 0.09 & 6.40 & Nd & Nd & Nd & Nd & Nd \\ \hline \multirow{2}{*}{PFVB2} & Initial & 3.86 \(\pm\) 0.10 & 6.37 & Nd & Nd & Nd & Nd & Nd \\  & Final & 3.70 \(\pm\) 0.10 & 6.25 & Nd & Nd & Nd & Nd & Nd \\ \hline \multirow{2}{*}{PFVB3} & Initial & 3.78 \(\pm\) 0.09 & 5.92 & Nd & Nd & Nd & Nd & Nd \\  & Final & 3.83 \(\pm\) 0.10 & 6.66 & Nd & Nd & Nd & Nd & Nd \\ \hline \multirow{2}{*}{PFVB4} & Initial & 4.11 \(\pm\) 0.09 & 6.77 & Nd & Nd & Nd & Nd & Nd \\  & Final & 3.99 \(\pm\) 0.12 & 6.50 & Nd & Nd & Nd & Nd & Nd \\ \hline \end{tabular} * Nd. Not detected (detection limit \(<\) 1.30 log\({}_{10}\) CFU/mL).  
\end{table} 
Table 2: Individual values of pH and microbiological data (log\({}_{10}\) CFU/mL) for the different types of PFVBs assayed at the initial (3 days) and final (52 days) sampling points. LAB stands for lactic acid bacteria group, Yea stands for fungi and molds, Ent stands for _Enterobacteriaceae_, Lis stands for _Listeria_, Sal stands for _Salmonella_, and Sta stands for _Staphylococcus_. _L.