## 4 Conclusions  
This work has revealed that in the context of young wine and oaked wine, the release of aldehydes due to the breakdown of the aldehyde-SO2 adducts causes a clear depreciation of the orthonasal aroma quality in wines. Furthermore, this depreciation is more evident \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Removal Percentage**} & \multicolumn{6}{c}{**Final Data**} \\ \cline{2-13}  & \multicolumn{2}{c}{**SO2 Free**} & \multicolumn{2}{c}{**SO2 Total**} & \multicolumn{2}{c}{**TPI**} & \multicolumn{2}{c}{**Colour**} & \multicolumn{2}{c}{**TA**} & \multicolumn{2}{c}{**pH**} \\  & **T1** & **T2** & **T1** & **T2** & **T1** & **T2** & **T1** & **T2** & **T1** & **T2** & **T1** & **T2** \\ \hline Control & & & & & & & & & 5.4 & 5.4 & 3.2 & 3.1 \\ SLB & \(-\)16 & \(-\)3.5 & 9.0 & 31 & 0.14 & \(-\)4.7 & 29 & 32 & 5.3 & 5.4 & 3.2 & 3.2 \\ ETDM & 0.10 & 13 & 17 & 23 & 12 & 10 & 16 & 20 & 3.5 & 3.6 & 3.7 & 3.8 \\ MAX & 11 & 37 & 22 & 27 & 45 & 42 & 76 & 75 & 5.3 & 5.4 & 3.2 & 3.1 \\ BEC & 6.0 & 11 & 27 & 16 & 8.6 & 3.8 & 24 & 20 & 5.6 & 5.6 & 3.2 & 3.1 \\ SXA & 13 & 19 & 38 & 34 & 48 & 44 & 85 & 83 & 5.2 & 5.3 & 3.2 & 3.1 \\ SXAW & 0.40 & 18 & 34 & 29 & 31 & 23 & 72 & 75 & 4.5 & 4.6 & 3.6 & 3.4 \\ DOW & 0.30 & 30 & 45 & 52 & 39 & 38 & 68 & 68 & 5.1 & 5.1 & 3.1 & 3.0 \\ IRA & 13 & 35 & 28 & 57 & 44 & 45 & 63 & 64 & 5.2 & 5.1 & 3.0 & 3.0 \\ \hline \hline \end{tabular}  
* Ti: test with the wine initial SO2 level (Free SO2: 12.8 mg/L. Total SO2: 142.8 mg/L). T2: test with wine spiked with SO2 (Free SO2: 36.8 mg/L. Total SO2: 172.8 mg/L).  
\end{table} 
Table 6: Removal percentage of SO2, colour and total polyphenol index (TPI) after 24 h of treatment with resins. Total acidity, TA (g/L tartaric acid) and pH after 24 h.  
when the total aldehyde levels are high. From a descriptive point of view, the fruity character of young wines is masked by showing attributes that define oxidation. Quality detriment begins at a tested level 4, which contains the following aldehyde concentrations: 13 \(\upmu\)g/L of methional, 49 \(\upmu\)g/L of phenylacetaldehyde, 17 \(\upmu\)g/L of isobutyraldehyde, 12 \(\upmu\)g/L of 2-methylbutanal and 24 \(\upmu\)g/L of 3-methylbutanal. More than 75% of recently opened commercial wines contain concentrations of total aldehydes higher than these, therefore, it seems reasonable to look for tools that reduce the presence of aldehydes responsible for oxidation aromas in wines. Working with white wine, mixed ion exchange resins have offered the best aldehyde removal results, maintaining, predominantly, the pH and total acidity, although reducing the colour by at least 20%. On the other hand, the addition of sulphur dioxide only significantly improves the removal of acetaldehyde and phenylacetaldehyde using pure ion exchange resins. Finally, the resin that has offered the best results has been the Strata X-A resin, which provides around 11-17% removal for isobutyraldehyde, 31-47% for 2-methylbutanal, 29-31% for 3-methylbutanal, 33-37% for methional, 78-86% for phenylacetaldehyde and 3-10% for acetaldehyde. However, due to the dose of resin used in the experiment (10 g/L), further investigation of this issue on an industrial scale would be necessary in order to reach applicability conclusions. Conceptualization, V.F. and A.E. ; experimental design, A.M.-C., M.B. and M.-P.S.-N.; methodology, A.M.-C., M.B. and A.d.-I.-F.-B. ; investigation, A.M.-C., M.B., A.d.-I.-F.-B. and M.-P.S.-N.; writing--original draft preparation, A.M.-C. and A.E. ; writing--review and editing, M.B., A.d.-I.-F.-B., M.-P.S.-N., A.E. and V.F. ; supervision and funding acquisition, V.F. and A.E. All authors have read and agreed to the published version of the manuscript. This work has been funded by the Spanish MINECO (Project AGL2014-59840 and AGL2017-87373-C3-1-R) and partly cofounded by the European Union (FEDER). Founding from Diputacion General de Aragon (T53) and Fondo Social Europeo is acknowledged. [PERSON] has received a grant from the Spanish FPI program.