## 3 Results
### Optical Properties of Red Pickly Pear Juice
\begin{table}
\begin{tabular}{l c c c c c c c} \multicolumn{1}{c}{**Treatment**} & \multicolumn{6}{c}{_Hue angle_} \\ \cline{2-9}  & \multicolumn{3}{c}{**pH 3.6**} & \multicolumn{3}{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) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.00\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) \\ UV-C (9.87 mJ/cm\({}^{2}\)) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.00\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.0\pm 0.0\)\({}^{\circ}\) \\ UV-C (15.13 mJ/cm\({}^{2}\)) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.00\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.1\pm 0.0\)\({}^{\circ}\) \\ HV-C (13.78 mJ/cm\({}^{2}\)) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.00\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.3\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.2\pm 0.0\)\({}^{\circ}\) & \(1.0\pm 0.0\)\({}^{\circ}\) \\ HTST (80 \({}^{\circ}\)C) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & \(1.4\pm 0.0\)\({}^{\circ}\) & N/A & N/A & N/A & N/A \\ UHT (130 \({}^{\circ}\)C) & N/A & N/A & N/A & N/A & \(0.8\pm 0.0\)\({}^{\circ}\) & \(0.8\pm 0.1\)\({}^{\circ}\) & \(1.00\pm 0.1\)\({}^{\circ}\) & \(1.0\pm 0.0\)\({}^{\circ}\) \\ \multicolumn{1}{c}{**} & \multicolumn{6}{c}{_Chroma*_} \\ \cline{2-9}  & \multicolumn{3}{c}{**pH 3.6**} & \multicolumn{3}{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) & \(64.8\pm 12\)\({}^{\circ}\) & \(65.2\pm 0.6\)\({}^{\circ}\) & \(65.0\pm 0.3\)\({}^{\circ}\) & \(64.8\pm 0.0\)\({}^{\circ}\) & \(64.4\pm 1.0\)\({}^{\circ}\) & \(64.3\pm 0.1\)\({}^{\circ}\) & \(65.7\pm 0.0\)\({}^{\circ}\) & \(60.5\pm 0.4\)\({}^{\circ}\) \\ UV-C (0.87 mJ/cm\({}^{2}\)) & \(64.1\pm 0.1\)\({}^{\circ}\) & \(63.6\pm 0.0\)\({}^{\circ}\) & \(64.4\pm 0.2\)\({}^{\circ}\) & \(64.0\pm 0.1\)\({}^{\circ}\) & \(60.0\pm 3.8\)\({}^{\circ}\) & \(61.7\pm 0.1\)\({}^{\circ}\) & \(61.6\pm 0.4\)\({}^{\circ}\) & \(55.9\pm 0.7\)\({}^{\circ}\) \\ UV-C (15.13 mJ/cm\({}^{2}\)) & \(63.2\pm 0.4\)\({}^{\circ}\) & \(63.6\pm 0.2\)\({}^{\circ}\) & \(64.1\pm 0.1\)\({}^{\circ}\) & \(62.6\pm 0.4\)\({}^{\circ}\) & \(62.0\pm 1.1\)\({}^{\circ}\) & \(60.9\pm 0.1\)\({}^{\circ}\) & \(61.5\pm 0.1\)\({}^{\circ}\) & \(57.3\pm 0.1\)\({}^{\circ}\) \\ UV-C (31.78 mJ/cm\({}^{2}\)) & \(62.8\pm 0.4\)\({}^{\circ}\) & \(62.6\pm 0.0\)\({}^{\circ}\) & \(63.3\pm 0.0\)\({}^{\circ}\) & \(63.3\pm 0.1\)\({}^{\circ}\) & \(60.9\pm 2.1\)\({}^{\circ}\) & \(61.1\pm 0.2\)\({}^{\circ}\) & \(61.1\pm 0.1\)\({}^{\circ}\) & \(56.6\pm 0.3\)\({}^{\circ}\) \\ HTST (80 \({}^{\circ}\)C) & \(60.7\pm 0. Effect of UV-C Irradiation and Thermal Treatment on the Chemical Properties of Red Prickly Pear juice (PPJP)  
Chemical analyses showed that the total polyphenol content in untreated juice at pH 3.6 (Figure 2a) and 7 (Figure 2b) decreased significantly (\(p<0.05\)) during storage, with contents of 159.32 and 153.18 mg GAE/L at day 0, respectively. The juice treated at day 0 by UV-C irradiation showed contents of 170.88 mg GAE/L (31.87 mJ/cm\({}^{2}\)) and 175.32 mg GAE/L (9.81 mJ/cm\({}^{2}\)), and HTST contents of 156.12 mg GAE/L for juice at pH 3.6. UV-C treatment showed values of 140.81 (31.87 mJ/cm\({}^{2}\)) to 152.38 mg GAE/L (9.81 mJ/cm\({}^{2}\)), and UHT treatment showed values of 156.98 mg GAE/L for juice at pH 7.