# Different SO\({}_{2}\) Doses and the Impact on Amino Acid and Volatile Profiles of White Wines
## 3 Results and Discussion
### Volatile Organic Compound
#### 3.1.3 Volatile Organic Compounds in Wines  
In this work for AV and BL wines, the relative amount of each analyte was calculated as the percentage ratio of the respective peak area in relation to the total peak area (RPA) of the chromatogram (Table S2 on Supporting Material). Only compounds that present an RPA above 0.0002% were considered for further statistical treatment. It was possible to tentatively identify 83 VOCs that were present in at least one sample. The analyses of the VOCs profile for AV and BL wines indicate that esters (47 compounds), alcohols (14 compounds), carboxylic acids (4 compounds), ethers (2 compounds), ketones  
Figure 1: SO\({}_{2}\) total and free concentration evolution during time of aging. On (**a**,**b**) are represented the Antão Vaz wine (AV), total and free forms, respectively. On (**c**,**d**) are represented the Blend wine (BL), total and free forms, respectively. The statistical results are presented on the graphic: different capital letters (A,B,C,D,E) means that each value differs significantly (one-way variance analysis, \(p\) < 0.05) according to SO\({}_{2}\) dose for each time, and different lowercase letters (a–c) means that each value differs significantly (one-way variance analysis, \(p\) < 0.05), according to time after fermentation for each SO\({}_{2}\) doses. (2 compounds), and aldehydes (2 compounds) were the most tentatively identified chemical groups, together with 12 miscellaneous compounds. Additional 51 compounds (unknowns) were also detected, but their identification assignments could not be carried out since the library match was below 850. The limit of 850 was the criterion established as the minimum limit to accept the tentative identification obtained from the library of spectra, together with the calculated LRI values. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Compound n\({}^{\circ}\)** & **LRIcal [LRIlit] * & **Compound [Common Name]** & **Most Abundant Ions (_un/z_)** \\ \hline \multicolumn{3}{c}{Esters} \\
1 & 892 [8  
The three most representative groups of VOCs are esters, alcohols, and miscellaneous compounds [52; 53]. Esters represent, by far, the group with the largest number of compounds, in which the more important contributors are ethyl acetate (8), ethyl hexanoate (12), isoamyl butyrate (14), ethyl octanoate (23) and ethyl decanoate (32). This class of compounds is related to the fermentative process, promoting different fruity aroma characteristics to the wines. This is indeed clear in the case of compounds 12 and 14, which were described to be often present above their sensory threshold [54]. Alcohols were the second more representative chemical class, in which 2-propanol (53), isopentyl alcohol (57), and phenethyl alcohol (66) present the higher percentual content. Indeed, esters, namely, ethyl esters and alcohols, were already reported as the two most important groups building the flavor bouquet of wines. Their presence is also an indicator of the important role of SO\({}_{2}\) after the fermentation process by preserving these compounds and inducing the evolution of the floral and fruity notes that they confer on wines [55; 56]. Performing an ANOVA analysis of VOCs for each compound in the different aging time periods and SO\({}_{2}\) conditions for each wine, it was possible to identify 14 compounds with a statistically relevant difference with a significance of \(p\) < 0.05. For both wines, the compounds: ethyl acetate (1), isoamyl acetate (8), ethyl hexanoate (12), ethyl octanoate (23), ethyl decanoate (32), 2-propanol (52), isopentyl alcohol (57), phenethyl alcohol (66) and octanoic acid (70) presented at least one statistical difference regarding aging time and/or SO\({}_{2}\) conditions.