## 3 Results and Discussion  
### Analysis of the Oenological Composition of the Base Wines  
Table 1 shows the oenological composition of the red base wines after 4 months of ageing on lees. The analysis of variance of the data showed statistically significant differences among the wines for neutral polysaccharides and astringency. For the other parameters, certain trends could be seen according to the treatment applied to the lees (Figure 1). Figure 1: Principal component analysis of wines and oenological parameters. Symbols. C: Control; L: Ultrasound-untreated lees; 30, 60, 90: ultrasound-treated at an amplitude level of 30%, 60%, and 90%, respectively. Code of oenological parameters (see Table 1). PCA analysis of the data was performed to evaluate the impact of ageing on ultrasound-treated lees on the oenological composition of the base wines. PC1 explained 49.56% of the variance, while PC2 explained 26.16%. The PCA plot (Figure 1) shows a considerable dispersion of the wine samples, with the wine aged on sonicated lees at an amplitude of 90% (sample 90) located at positive values for both PC1 and PC2, the wine aged on lees treated at 60% (sample 60) at negative value of PC1 and positive value of PC2, and a group of three wines (wine aged on lees treated at 30% (sample 30), wine aged on ultrasound-untreated lees (sample L) and control wine without lees (sample C)) at positive values of PC1 and negative of PC2. Sample 90 was characterized by high values on parameters related to wine colour, such as % red, colour intensity, anthocyanins and total polyphenol index (Figure 1), although no statistically significant differences were found among the wines. These results are in line with those published by [PERSON] et al. [9], which reported that ageing on sonicated lees increased the concentration of anthocyanins compared to untreated lees; this was probably due to a decrease in the adsorption of these compounds on the ultrasound-treated lees, although these authors also observed a decrease in the colour intensity of wine without changes in its tonality and total polyphenol index. High concentrations of polymers released during yeast autolysis, such as polysaccharides and proteins, the latter with no statistically significant difference among the wines, were also found in this wine (sample 90). In contrast, some other parameters (% yellow, tonality, as well as the phenolic families hydroxycinnamic acids and flavonoids) were associated with sample 60. Finally, the wine aged on ultrasound-treated lees at the amplitude of 30% (sample 30), the wine aged on ultrasound-untreated lees (L) and the control wine (C) showed high values for parameters related to wine astringency (tannins and astringency), although no statistically significant difference was found for the tannins among the wines. These results show that the application of ultrasound at high amplitudes improves to some extent the chromatic and polyphenic features of the wine, and more notably it enhances the concentration of neutral polysaccharides, reducing its astringency (chemically evaluated). It seems that the application of ultrasound at 30% of amplitude (sample 30) is not sufficient to enhance the physico-chemical characteristics of wine.