## 3 Results and Discussion
### Enological Parameters
Anthocyanins have a high antioxidant capacity, which are very beneficial for people's health ([PERSON], 2018). During _Fondillon_ oxidative aging, anthocyanins undergo different oxidation reactions such as condensation and polymerization, producing changes in the initial bluish tones transforming them into orange ([PERSON], 2018). The parameter \"tonality\" (Y/R) measures the relationship between the intensity of the yellow component, Y (420 nm), and red one, R (520 nm). In the studied _Fondillon_ samples, significant positive and negative correlations were observed among the tonality and (i) the Y component (R\({}^{2}\) = 0.987; \(p\) < 0.001) and (ii) R component (R\({}^{2}\) = 0.982; \(p\) < 0.001), respectively (Figure 1a). These relationships meant that during aging there was an increase in the Y component and a decrease in the R component, leading to an increase in the wine tonality. These results agreed with those reported by [PERSON] et al. (2018) in their study of the changes of phenolic fraction of red wines (cultivar Tempranillo) aged in oak barrels. Regarding the parameter \"color intensity\", a positively correlation was observed with TPI (R\({}^{2}\) = 0.690; \(p\) < 0.01) and the TA (R\({}^{2}\) = 0.757; \(p\) < 0.01) (Figure 1b,c). These correlations meant that a high color intensity was linked to a high content of polyphenols and anthocyanins. In this way, the _Fondillon_ sample with the highest values of color intensity (5.49), color density (4.80), R component (33.3), B component (12.5), and TA (0.76 mg L\({}^{-1}\)) was that of the 1960 _solera_, which at the same time had the lowest values of the tonality (1.62) and Y component (54.1) (Table 2); all these values made _Fondillon solera_ 1960 the most special one within the studied wine collection. The presence of phenolic compounds in wines has a direct effect on their antioxidant activity. The most important phenolics in wine are flavonoids (anthocyanins, flavanols and flavanols), which play a key role in the wine antioxidant activity and sensory profile, by influencing color, astringency, and bitterness (2018). In this way, a significant positive correlation was found between TPI and TCT (R\({}^{2}\) = 0.615; \(p\) < 0.05); however, no other significant correlations were found among TPI, TCT, and TA (Table S2). For the analysis of the antioxidant activity, three methods were used: ABTS\({}^{\bullet+}\), DPPH\({}^{\bullet}\), and FRAP, because each one of them has different mechanisms of action. Table 2 shows that the _Fondillon_ that presented the highest value for the three methods again was that of the _solera_ 1960: ABTS\({}^{\bullet+}\) (2.02 mmol Trolox kg\({}^{-1}\)), FRAP (4.97 mmol Trolox kg\({}^{-1}\)), and DPPH\({}^{\bullet}\) (64.4%), with the _solera_ 1996 (the youngest _Fondillon_ under study) being on the opposite side (lowest AA values): ABTS\({}^{\bullet+}\) (1.28 mmol Trolox kg\({}^{-1}\)), FRAP (4.28 mmol Trolox kg\({}^{-1}\)), and finally DPPH\({}^{\bullet}\) (29.9%). It was also observed that there were significant positive correlations among the TA and ABTS\({}^{\bullet+}\) (R\({}^{2}\) = 0.645; \(p<0.01\)) and DPPH\({}^{\bullet}\) (R\({}^{2}\) = 0.640; \(p<0.01\)) (Figure 1d); no significant effect was observed on FRAP. These results agreed with those presented by [PERSON] et al. [15], when they studied the phenolic composition and antioxidant activity of minor grape varieties (Sabater, Gorgollassa, Escursac, Giro Ros, and Quigat) from the Balearic Islands (Spain) and concluded that the higher the total phenolic content, the higher the antioxidant activity. The current experimental data showed a general trend of an increase in the DPPH\({}^{\bullet}\) with the aging time (R\({}^{2}\) = 0.224; \(p<0.05\)). No clear trend was found for the ABTS\({}^{\bullet+}\) or FRAP data. The DPPH\({}^{\bullet}\) trend found in _Fondillion_ agreed with the results published by [PERSON] et al.