## 3 Results
### Optical Properties of Red Pickly Pear Juice
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{8}{c}{**Mesophilic (Log CFU/mL)**} \\ \cline{2-9}  & \multicolumn{4}{c}{**pH 3.6**} & \multicolumn{4}{c}{**pH 7**} \\ \cline{2-9}  & **Day 0** & **Day 5** & **Day 10** & **Day 20** & **Day 0** & **Day 5** & **Day 10** & **Day 20** \\ \hline Untreated juice (Control) & 6.17 \(\pm\) 0.08 & 6.28 \(\pm\) 0.13 & 5.22 \(\pm\) 0.15 & ND & 6.41 \(\pm\) 0.01 & 8.23 \(\pm\) 0.01 & 8.21 \(\pm\) 0.05 & ND \\ \hline UV-C (9.87 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & ND & ND \\ \hline UV-C (15.13 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & ND & ND \\ \hline UV-C (31.78 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & ND & ND \\ \hline HTST (80 \({}^{\circ}\)C) & ND & ND & ND & ND & N/A & N/A & N/A & N/A \\ \hline UHT (130 \({}^{\circ}\)C) & N/A & N/A & N/A & N/A & ND & ND & ND & ND \\ \hline \multicolumn{9}{c}{**Psycrophilic (Log CFU/mL)**} \\ \cline{2-9}  & \multicolumn{4}{c}{**pH 3.6**} & \multicolumn{4}{c}{**pH 7**} \\ \cline{2-9}  & **Day 0** & **Day 5** & **Day 10** & **Day 20** & **Day 0** & **Day 5** & **Day 10** & **Day 20** \\ \hline Untreated juice (Control) & 5.57 \(\pm\) 0.02 & 4.94 \(\pm\) 0.03 & 4.25 \(\pm\) 0.06 & ND & 5.55 \(\pm\) 0.05 & 4.47 \(\pm\) 0.00 & ND & ND \\ \hline UV-C (9.87 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & 1.06 \(\pm\) 0.00 & 3.47 \(\pm\) 0.00 & ND \\ \hline UV-C (15.13 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & 1.5 \(\pm\) 0.11 & 3.47 \(\pm\) 0.01 & ND \\ \hline UV-C (31.78 mJ/cm\({}^{2}\)) & ND & ND & ND & ND & ND & 3.47 \(\pm\) 0.02 & ND \\ \hline HTST (80 \({}^{\circ}\)C) & ND & ND & ND & ND & N/A & N/A & N/A & N/A \\ \hline UHT (130 \({}^{\circ}\)C) & N/A & N/A & N/A & N/A & N/A & N/A & N/A \\ \hline \multicolumn{9}{c}{Mean \(\pm\) standard deviation. ND = Not Detectable N/A = Treatment not performed.} \\ \end{tabular}
\end{table} 
Table 2: _Cont._  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{8}{c}{**pH 3.6**} & \multicolumn{4}{c}{**pH 7**} \\ \cline{2-9}  & **Day 0** & **Day 5** & **Day 10** & **Day 20** & **Day 0** & **Day 5** & **Day 10** & **Day 20** \\ \hline Untreated juice (Control) & 3.7 \(\pm\) 0.04 & 3.7 \(\pm\) 0.1 \({}^{\circ}\) & 3.6 \(\pm\) 0.0 \({}^{\circ}\) & 7.0 \(\pm\) 0.0 \({}^{\circ}\) & 3.8 \(\pm\) 0.0 \({}^{\circ}\) & 3.8 \(\pm\) 0.0 \({}^{\circ}\) & 3.8 \(\pm\) 0.0 \({}^{\circ}\) \\ UV-C (9.87 mJ/cm\({}^{2}  
tion method [9]. Mesophilic aerobics had an inactivation of initial load (6.17 and 6.41 log mesophilic CFU/mL) for juice at pH 3.6 and 7.0, respectively. Psychrophiles were diminished by 5.55 log CFU/mL for the juice at pH 3.6 and 5.57 log CFU/mL for juice at pH 7.0. An effective decline in total aerobic microorganisms is not always achieved. [PERSON] and [PERSON] [33] processed orange juice with an initial total aerobe load of 3.25 log CFU/mL using UV-C radiation and reduced it to 2.96 log CFU/mL using a dose of 48.12 KJ/L. This study demonstrated that the UV-C processing of acidified red prickly pear juice (pH 3.6) could be used to provide a safe product for public consumption. Effect of UV-C Irradiation and Thermal Treatment on the Physical Properties of Red Prickly Pear juice (PPIP)  
The total soluble solids did not differ significantly (\(p>0.05\)) between the control juice (4.0 Brix) and the juice processed using both treatments (UV-C and thermal) and were maintained during storage. [PERSON] et al. [34] also reported that UV-C radiation did not affect the total soluble solids of pineapple juice. The pH and acidity differed significantly (\(p<0.05\)) during storage time (Table 3), specifically with the pH-neutral (pH 7) untreated juice, which showed a decrease in pH and an increase in acidity. These changes are related to microbial growth in the control juice (untreated and not-acidified), specifically the total coliform, mold, and yeast loads, as well as mesophilic microorganisms (Table 2). However, treated juices (UV-C and thermal) did not show changes in pH during storage time.