## 2 Results and Discussion
### Desorption
The quadratic effect of the ethanol concentration in the eluting solvent was only significant on desorption yields whereas the linear effect of this variable was significant on all objective functions during operation with HP20. With SP207, the linear effect of the ethanol concentration was significant on all functions, except on the phenolic content of the product. Operating with XAD16 HP the quadratic effect of the ethanol concentration was the most significant, followed by the interaction effect between temperature and ethanol, particularly on the phenolic and sugar content of the extracts and on the radical scavenging capacity. A comparison between the experimental and calculated objective functions for randomly selected operational conditions confirmed the good prediction ability of the models for all resins (Table 6). The response surface models and the contour plots defined with the variables significant at 90% level are shown in Figure 2 for the studied objective functions. \begin{table}
\begin{tabular}{l c c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Real**} & \multicolumn{3}{c}{**Coded**} & \multicolumn{3}{c}{**Objective Functions**} \\ \cline{2-13}  & \multicolumn{3}{c}{**Variables**} & \multicolumn{3}{c}{**Variables**} & & & & & & & & & & \\ \cline{2-13}
**Resin** & \multicolumn{3}{c}{**T**} & **EtOH** & **T** & **E** & \multicolumn{3}{c}{**Y\({}_{\text{leap}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{leale}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{2 exp}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{2 cale}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{3 exp}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{2 cale}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{4 exp}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{5 exp}}\)**} & \multicolumn{3}{c}{**Y\({}_{\text{Scale}}\)**} \\  & **(\%C)** & **(\%)** & & & & & & & & & & & & \\ \hline HP20 & 50 & 96 & 1.5 & 1.4142 & 56.8 & 59.8 & 22.9 & 23.2 & 0.473 & 0.475 & 0.266 & 0.297 & 13.3 & 14.0 \\ SP207 & 50 & 96 & 1.5 & 1.4142 & 60.0 & 61.0 & 21.6 & 24.2 & 0.521 & 0.570 & 0.291 & 0.318 & 12.7 & 13.7 \\ XAD16 HP & 45 & 96 & 1 & 1.4142 & 39.3 & 40.8 & 16.3 & 14.5 & 0.272 & 0.343 & 0.163 & 0.202 & 8.39 & 5.93 \\ \hline \multicolumn{13}{l}{Y\({}_{1}\): Phenolic desorption yield (\%); Y\({}_{2}\): Sugars desorption yield (\%); Y\({}_{3}\): Total phenolic content (g GAE/g extract); Y\({}_{4}\): Total sugar content (g D-glucose/g extract); Y\({}_{5}\): Radical scavenging activity (mM Trolox).} \\ \end{tabular}
\end{table} 
Table 6: Comparison between experimental and calculated values of the objective functions at the optimal conditions. Figure 2: Response surface of the objective functions studied to optimize the desorption stage of phenolic compounds, sugars and radical scavengers from XAD-16 HP, SP207 and HP20 resins. The eluted product presented a yellow-light brown colour, powder texture and a characteristic winery odour with a phenolic content of 50% d.b., higher than that of some commercial ingredients [16] and other concentrated refined products, such as those from olive mill wastewaters concentrated with resins [17]. The final extracts contained 25% sugars and for some applications the removal of organic acids and sugars would be desirable [8]. The phenolic compounds were expressed as total phenolics, although the liquid chromatography profile of the product obtained with the selected resins (Sepabeads SP207) revealed the presence of monomeric compounds (gallic acid, catechin, epicatechin, quercetin), oligomeric and polymeric phenols. The degree of polymerization of the phenolic compounds recovered from the winery wastes was 3, slightly higher than those from distillery byproducts of the same origin and different year obtained in the retentates of nanofiltration membranes and further recovered with Sepabeads SP700 [4]. Degrees of polymerization in the range 1-3.7 have been reported for other grape extracts, and this criteria was confirmed to be important for modulating the antioxidant capacity with the lowest  
Figure 2: Cont. cytotoxic efects [18,19].