## 2 Results and Discussion
### Effect of RO-EP Treatment and Alcohol Re-Adjustment on Basic Wine Composition
For wines A and B, the lightness (\(L^{\star}\)) decreased by 7 and 4%, and hue intensities (\(a^{\star}\) and \(b^{\star}\)) increased by 6 and 4%, respectively; whereas for wine C, lightness stayed the same, \(a^{\star}\) decreased slightly and \(b^{\star}\) increased substantially. The subsequent addition of ethanol to dealcoholized wines did not restore the color properties of wines to those observed prior to RO-EP treatment, with alcohol re-adjustment affecting the color of individual wines in different ways. Wine C was not significantly different in color but for wines A and B, ethanol re-adjustment decreased the intensity of wine color compared to that of wine post RO-EP, presumably as a consequence of dilution. In the case of wine B, wine color following ethanol addition was even significantly lower than that observed prior to RO-EP treatment (18.8 vs. 19.6, Table 1), which was not the case for Wine A (12.2 vs. 10.8). The hue of dealcoholized wines decreased following alcohol re-adjustment compared to that of wine pre RO-EP, but to higher, lower and comparable levels for wines A, B and C, respectively. Differences in color are expected to be detectable to the human eye where \(\Delta E^{\star}\) is \(\geq\) 3.0 [20], thus, partial dealcoholization visibly affected the wine color for wines A and C (\(\Delta E^{\star}\) = 5.3 and 3.0, respectively, Table 1), with a perceivable color difference remaining in wine A even after alcohol re-adjustment (\(\Delta E^{\star}\) = 4.0). \begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Wine A**} & \multicolumn{3}{c}{**Wine B**} & \multicolumn{3}{c}{**Wine C**} \\ \cline{2-13}  & **Pre-RO-EP** & **Post-RO-EP** & **Post-EOH** & **P** & **Pre-RO-EP** & **Post-RO-EP** & **Post-EOH** & **P** & **Pre-RO-EP** & **Post-RO-EP** & **Post-EOH** & **P** \\ \hline alcohol (\%: abs) & 14.1a & 12.5b & 14.1a & \(<\)0.001 & 17.1a & 14.5b & 17.1a & \(<\)0.001 & 14.9a & 14.2b & 14.5u & -0.001 \\ free SO\({}_{2}\)(mg/L) & 3.8 & nd & nd & – & 6.4 & nd & nd & – & 7.7 & 1.9 & 1.9 & – \\ density (g/mL) & 0.995 & 0.995 & 0.993 & - & 0.993 & 0.996 & 0.993 & – & 0.993 & 0.994 & 0.993 & – \\ viscosity (mg/Ls) & 185.8a & 1711c & 179b & \(<\)0.001 & 2009a & 1852b & 1982b & \(<\)0.001 & 1858a & 1751c & 1850b & -0.001 \\ glycerol (g/L) & 10.2a & 10.2a & 10.0b & \(<\)0.001 & 10.9b & 11.0a & 10.7c & \(<\)0.001 & 11.9a & 11.8a & 11.8b & 0.009 \\ gelatin index (\%) & 38c & 55a & 46 b & \(<\)0.001 & 49 & 54 & 48 & – & 44 & 44 & 41b & 0.004 \\ pH & 3.7 & 3.6 & 3.7 & – & 3.6 & 3.6 & 3.6 & – & 3.7 & 3.7 & 3.7 & – \\ TA (g/L) & 5.9 & 6.1 & 5.9 & – & 7.2 & 7.1 & 7.2 & – & 6.4 & 6.5 & 6.4 & – \\ VA (g/L) & 0.4 & 0.3 & 0.4 & – & 0.5 & 0.8 & 0.5 & – & 0.6 & 0.6 & 0.6 & – \\ citric acid (g/L) & 1.2 & 1.2 & 1.1 & – & 0.7 & 0.7 & – & 0.9 & 0.9 & 0.8 & – \\ succin acid (g/L) & 6.2 & 6.2 & 6.1 & – & 8.2 & 8.3 & 8.3 & – & 6.5 & 6.5 & 6.4 & – \\ lactic acid (g/L) & 3.7 & 3.8 & 3.7 & – & 2.8 & 2.8 & 2.8 & – & 3.8 & 3.8 & 3.7 & – \\ wine color (au) & 10.8c & 12.6a & 12.2b & +0.001 & 19.6b & 21.0a & 18.5c & \(<\)0.001 & 17.2 & 17.3 & 17.1 & – \\ wine hue & 2.8c & 4.9a & 3.8b & \(<\)0.001 & 4.1b & 4.2a & 3.9c & \(<\)0.001 & 3.4b & 3.6a & 3.6b & -0.001 \\ \(L^{*}\) & 67.6a & 62.7c & 64.0b & \(<\)0.001 & 49.7a & 47.5b & 49.8a & \(<\)0.001 & 25.9b & 53.1a & 52.7c & 0.003 \\ \(\mu^{*}\) & 34.7e & 36.8a & 36.1b & \(<\)0.001 & 50.8b & 52.6a & 50.9b & \(<\)0.001 & 49.5a & 48.5b & 49.6a & -0.001 \\ \(\mu^{*}\) & 5.0k & 5.6b & 5.8a & \(<\)0.001 & 5.3a & 3.3b & \(<\)0.001 & 6.0b & 3.4a & 0.5b & -0.001 \\ AE\({}^{1}\) & – & 5.3 & 4.0 & – & – & 2.7 & 2.0 & – & – & 3.0 & 0.3 & – \\ \hline \multicolumn{10}{l}{Values are means of duplicate measurements (n = 2). Standard errors were \(\leq\)10\%; nd = not detected. Values followed by different letters within rows (for each wine) are statistically significantly different. \({}^{1}\)Total color differences (\(\Delta\)F\({}^{2}\)) were calculated relative to the color of each wine prior to RO-EP treatment.} \\ \end{tabular}
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