# Different SO\({}_{2}\) Doses and the Impact on Amino Acid and Volatile Profiles of White Wines
## 4 Conclusions  
Two white wines from Alentejo were aged with different SO\({}_{2}\) doses applied after fermentation. The samples were analyzed 3, 6, and 12 months after SO\({}_{2}\) addition. When an ANOVA was performed to VOCs percentual content for both wines, ethyl acetate (1), isoamyl acetate (8), ethyl hexanoate (12), hexyl acetate (14), ethyl octanoate (23), ethyl decanoate (31), 2-propanol (52), isopentyl alcohol (56), and phenethyl alcohol (64)  
Figure 5: Principal component biplot illustrating the simultaneous projection of the wine and amino acids of Antão Vaz (**A**) and Blend wine (**B**). Black dot—wine samples with the respective SO\({}_{2}\) concentration applied; Blue triangle—amino acid. Amino acids: Aspartic acid (Asp), glutamine (Gln), asparagine (Asn), glutamic acid (Glu), glycine (Gly), threonine (Thr), arginine (Arg), alanine (Ala), \(\gamma\)-aminobutyric acid (GABA), proline (Pro), tyrosine (Tyr), valine (Val), methionine (Met), cysteine (Cys), tryptophan (Trp), leucine (Leu), phenylalanine (Phe), ornithine (Orn) and lysine (Lys). presented, at least, one statistical difference regarding the time of aging and/or SO\({}_{2}\) conditions. It was also observed that ethyl laurate (41) for AV and ethyl isovalerate (6), diethyl succinate (35), and ethyl lactate (71) for BL, showed statistically significant differences although being present in both wines. Analyzing the PCAs for each wine, it is possible to verify that the initial wines are completely different from the aged wines, independently of the addition or absence of SO\({}_{2}\). The same is observed for wines aged for 12 months. When wines were aged for 3 and 6 months (in the case of AV), it led to well-distinct samples, probably because AV wines are more susceptible to the oxidation-developed aroma in comparison with Blend wines (BL), which appear to be more stable to that action. Regarding the two factors under study, aging time and different doses of SO\({}_{2}\), it is clear that time has a major impact on VOCs profile than the addition of different SO\({}_{2}\) doses. Regarding amino acids profile, proline, arginine, and \(\gamma\)-aminobutyric acid are the most predominant in both studied wines. In general, and as expected, with maturation over lees, the total AAs concentration increased in comparison with initial wines, but SO\({}_{2}\) also influenced the increase of the AAs, especially on the AV wines. The cases where 60 and 90 mg/L of SO\({}_{2}\) were applied led to the highest AA concentration. Considering these results, it seems possible to reduce SO\({}_{2}\) amounts without compromising the volatile profiles of wines since time plays a more dominant role than SO\({}_{2}\) doses. Lower amounts of SO\({}_{2}\) do not compromise the normal evolution of volatiles and the normal reduction of free and total SO\({}_{2}\) over time. In fact, taking into consideration this work, in the future, a SO\({}_{2}\)-reducing practice in winemaking could be attempted, owing this strategy does not negatively impact the evolution of wine aromas. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/beverages9020033/s1](https://www.mdpi.com/article/10.3390/beverages9020033/s1)]([https://www.mdpi.com/article/10.3390/beverages9020033/s1](https://www.mdpi.com/article/10.3390/beverages9020033/s1)), Table S1: SO\({}_{2}\) total and free concentration evolution during time of aging. On (a) Antao Vaz wines (AV) total and free forms and (b) Blend wines (BL) total and free forms; Table S2: Relative amount of each compound, calculated as the percentage ratio of the respective peak area in relation to relative to the total-peak area (RPA) of the chromatogram; Table S3: Amino acid quantification in AV--(a) and BL--(b) wines. Table S4: Total amino acid concentration in AV and Blend wines. Conceptualization, M.J.C. and M.G.d.S. ; data curation, C.V.A.S. and C.P. ; formal analysis C.V.A.S. ; funding acquisition, M.J.C. and M.G.d.S. ; investigation, C.V.A.S. ; methodology, C.V.A.S., C.P.