## 2 Results and Discussion
### Physicochemical Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & **TSS** & **TA** & & & & & & \\  & (\({}^{\circ}\)Brix) & **(\% Citric Acid)** & **pH** & **L\({}^{*}\)** & **a\({}^{*}\)** & **b\({}^{*}\)** & **C\({}^{*}\)** & **h** \\ \hline UJ & 12.75 \(\pm\) 0.00 B & 1.38 \(\pm\) 0.02 & 3.32 \(\pm\) 0.03 & 39.67 \(\pm\) 0.02 b & 27.48 \(\pm\) 1.71 & 17.37 \(\pm\) 0.78 & 32.51 \(\pm\) 1.87 & 32.33 \(\pm\) 0.45 \\ PEFJ 0 days & 12.86 \(\pm\) 0.01 A & 1.35 \(\pm\) 0.11 & 3.30 \(\pm\) 0.01 & 40.57 \(\pm\) 0.13 a & 28.10 \(\pm\) 1.31 & 17.79 \(\pm\) 0.36 & 33.26 \(\pm\) 1.30 & 32.35 \(\pm\) 0.68 \\ \hline  & & & & & & & & \\  & **TSS** & **TA** & & & & & & \\  & **(\({}^{\circ}\)Brix)** & **(\% citric acid)** & **pH** & **L\({}^{*}\)** & **a\({}^{*}\)** & **b\({}^{*}\)** & **C\({}^{*}\)** & **h** \\ \hline PEFJ-0 days & 12.86 \(\pm\) 0.01 C & 1.35 \(\pm\) 0.11 b & 3.30 \(\pm\) 0.01 & 40.57 \(\pm\) 0.13 & 28.10 \(\pm\) 1.31 & 17.79 \(\pm\) 0.36 & 33.26 \(\pm\) 1.30 & 32.35 \(\pm\) 0.68 \\ PEFJ-5 days & 13.02 \(\pm\) 0.01 B & 1.50 \(\pm\) 0.08 b & 3.29 \(\pm\) 0.00 & 41.18 \(\pm\) 0.12 & 26.47 \(\pm\) 0.31 & 17.94 \(\pm\) 0.09 & 31.98 \(\pm\) 0.21 & 34.13 \(\pm\) 0.44 \\ PEFJ-10 days & 13.02 \(\pm\) 0.00 B & 1.63 \(\pm\) 0.02 b & 3.26 \(\pm\) 0.01 & 41.18 \(\pm\) 0.39 & 26.35 \(\pm\) 0.58 & 17.82 \(\pm\) 0.49 & 31.82 \(\pm\) 0.21 & 34.08 \(\pm\) 1.32 \\ PEFJ-15 days & 12.99 \(\pm\) 0.00 B & 1.74 \(\pm\) 0.00 a & 3.30 \(\pm\) 0.00 & 40.58 \(\pm\) 1.37 & 26.74 \(\pm\) 1.55 & 17.89 \(\pm\) 0.70 & 32.21 \(\pm\) 0.90 & 33.85 \(\pm\) 2.57 \\ PEFJ-20 days & 13.24 \(\pm\) 0.02 A & 1.76 \(\pm\) 0.02 a & 3.26 \(\pm\) 0.01 & 41.73 \(\pm\) 0.45 & 25.58 \(\pm\) 0.93 & 18.31 \(\pm\) 0.53 & 31.47 \(\pm\) 0.44 & 35.63 \(\pm\) 1.77 \\ \hline \end{tabular}
\end{table} 
Table 1: Physicochemical parameters in UJ (untreated juice) and PEFJ (PEF-treated juice) immediately after the process (T0) and during further refrigerated storage at 4 \({}^{\circ}\)C. Data are expressed as means of three analytical replicates \(\pm\) standard deviation. Means in the same column followed by different letters are significantly different: \(p\leq\) 0.01—capital letter; \(p\leq\) 0.05—small letter; \(n\) = 3.  
affect consumer acceptance; therefore, it is very important to apply stabilizing technologies that do not produce detrimental variations in the color of fruit juices. Our results suggest a great potentiality for the PEF process to be applied as a stabilizing technology for the maintenance of the fresh-like color of refrigerated blood orange juice. Cloud is a significant quality attribute of orange juice that contributes to its flavor, aroma, and turbidity [29]. The pectinethylesterase (PME) enzyme causes a loss of cloud in freshly squeezed citrus juices. The loss of turbidity is mainly linked to the activity of PME, which is responsible for the demethylation of petrins. In citrus fruits, petrins, although distributed throughout almost the entire fruit, are more localized in the albedo; therefore, following squeezing they are found in large quantities in the juices. In the extracted juice, petrins act as protective colloids, helping to preserve juice cloud and preventing the aggregation and subsequent precipitation of very fine pulp fragments. Furthermore, petrins contribute to the body of the juice, which also contributes to maintaining its characteristic color. The demethylating activity of PME causes pectin to lose its peculiar function as a protective colloid, leading to the irreversible precipitation of the substances responsible for the juice cloud. This is the reason why the inactivation of PME is strictly needed to preserve orange juice cloud stability [13; 17; 25]. The results of the cloud values and PME activity on UJ and PEFJ immediately after the process and during further refrigerated storage at 4 \({}^{\circ}\)C are reported in Figures 1 and 2, respectively.