# Different SO\({}_{2}\) Doses and the Impact on Amino Acid and Volatile Profiles of White Wines
## 3 Results and Discussion
### Amino Acids  
Amino Acids Analysis  
The AAs content in AV and BL wines was also evaluated in this work for initial wines and wines after 3 months on lees. An ANOVA analysis was also performed for each AA, and results are presented in Table S3 on Supporting Material. The most represented AAs were proline and \(\gamma\)-aminobutyric acid for both wines, either in the initial wine or 3 months over lees after the addition of different doses of SO\({}_{2}\), as already reported by [PERSON] et al., 2021 [25] for other wine varieties. Regarding ANOVA results, one observed, for both wines, that aspartic acid, glutamic acid, asparagine, \(\gamma\)-aminobutyric acid, proline, and ornithine present at least one statistical difference, either in relation to the initial wine and/or in relation to the different SO\({}_{2}\) doses applied. The differences observed, despite being in the same AAs, did not show the same pattern for the two wines under study. Alanine presented a statistical difference only in BL wines. Figure 4 represents the histogram of total AAs content with wines after fermentation as a reference. For AV (Figure 4A) and BL (Figure 4B) wines, the time over fine lees leads to an increase of AAs concentrations, as already reported in the literature. Indeed, this behavior can be related to yeast autolysis after the decrease of viable cells during maturation over fine lees [25; 26; 58]. The main known factors that affect yeast autolysis are pH, temperature, ethanol content, and yeast strain. All these factors were kept constant in these wines; hence our results suggest that SO\({}_{2}\) doses may also play a role in AA released by yeast autolysis, despite the value found for AV wine with 120 mg/L of SO\({}_{2}\). In Table S4 of the Supporting Material, it is observed that the AAs concentration for both wine samples (AV and BL), considering the SO\({}_{2}\) amount, present significant differences at \(p<0.05\). Nevertheless, more studies are ongoing to go deeper into this subject in order to clarify it. Figure 4: Histogram of total amino acids content with wines after fermentation as reference, (**A**) Antão Vaz wines and (**B**) Blend wines. The total concentration was calculated by subtraction and division of total amino acid area for each dose with the total area obtained for wine after fermentation (t = 0) before adding SO\({}_{2}\). Figure 5 illustrates the PCA for (a) AV wines and (b) BL wines with data normalized using wines after fermentation as a reference in order to mitigate the predominance of variables with higher values. The impact of different doses of SO\({}_{2}\) is different for the two wine samples. In the case of AV wines (A), PC1 explains 88.43%, and PC2 explains 7.18% of the wine samples distribution. These samples are well spread over the plane defined by the two PCs regarding SO\({}_{2}\) addition. Wines with 0 and 30 mg/L of SO\({}_{2}\) are on the positive side of PC1 and the negative side of PC2; however, no AA is positively related. The addition of 60 and 90 mg/L of SO\({}_{2}\) led to similar wines in the positive side of PC1 and PC2 and was positively influenced by lysine in the case of 60 mg/L of SO\({}_{2}\) and proline in the case of 90 mg/L of SO\({}_{2}\). The wines with the addition of 120 mg/L of SO\({}_{2}\) were more similar to the initial AAs content, although located in a different quadrant. In the case of BL wines (B), PC1 explains 63.15% and PC2 26.94% of the wine samples distribution. In wines without SO\({}_{2}\), ornithine and threonine were more affected and presented a higher increase compared to other SO\({}_{2}\) condition samples. For 60 mg/L of SO\({}_{2}\) addition, aspartic acid, valine, and phenylalanine were positively affected, showing higher values. Wines with 30, 90, and 120 mg/L of SO\({}_{2}\) seem to be more similar and positively influenced by proline, arginine, and glutamine. Proline and arginine content increased in a more antioxidant environment, and glutamine content was higher at 90 mg/L of SO\({}_{2}\).