## 3 Results and Discussion  
### Enological Parameters  
The legislation of the DOP Alicante establishes several thresholds for the physico-chemical parameters in _Fondillon_ samples. In this way, the total acidity must be above 3.50 g of tartaric acid L\({}^{-1}\), the volatile acidity must be below 1.50 g of acetic acid L\({}^{-1}\), and the total alcohol content must be above 16% \(v/v\)[23]. Regarding the present results, the factor \"_solera_\" did not significantly affect either the pH or the relative density; however, there were significant effects on the rest of parameters, although without a clear trend with the \"_solera_\" age (Table 1). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multirow{2}{*}{**pH**} & \multicolumn{2}{c}{**Relative Density (20 \({}^{\circ}\)C)**} & **Total Alcohol Content** & **Total Acidity** & **Volatile Acidity** \\ \cline{2-6}  & & **(g mL\({}^{-1}\))** & **(\% w/v)** & **(g tartaric acid L\({}^{-1}\))** & **(g acetic acid L\({}^{-1}\))** \\ \hline \multicolumn{6}{c}{**ANOVA**\({}^{\ddagger}\)} \\ \cline{2-6}  & **NS** & **NS** & **\(\ast\ast\)** & **\(\ast\ast\)** & **\(\ast\ast\)** \\ \hline \multicolumn{6}{c}{**Tukey Multiple Range Test**\({}^{\ddagger}\)} \\ \hline
1930 & 3.55 & 0.9967 & 21.17 a & 8.63 ab & 1.16 cd \\
1944 & 3.67 & 1.0098 & 20.46 ab & 8.40 ab & 1.46 ab \\
1950 & 3.59 & 0.9972 & 19.30 ab & 8.63 ab & 1.13 d \\
1960 & 3.44 & 0.9985 & 19.60 ab & 10.01 a & 1.31 bc \\
1969 & 3.68 & 0.9978 & 18.53 ab & 9.00 ab & 1.37 ab \\
1975 & 3.82 & 1.0000 & 18.93 ab & 7.80 b & 1.01 d \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Basic enological parameters of _Fondillon_ wines as affected by the “_solera_” factor. The pH plays an important role in the stability and sensory quality of the wine as it is linked to longevity, aroma, and color [24]. The pH of red wines must range between 3.30 and 3.60, because above these values the wines could have a flat flavor and on the contrary, below this threshold the wines would be harsh and could be unpleasant for consumption [21]. The pH of the _Fondillon_ samples under study ranged between 3.35 (_solera_ 1980) and 3.82 (_solera_ 1975) and presented a mean value of 3.56 (Table 1). Thus, these values are within the previously mentioned parameters to meet the normality range, except for three values, which were slightly above the legal thresholds, perhaps implying a low negative effect of the aging process. [PERSON] et al. [25] studied the effect of (i) type and (ii) age of on the main physico-chemical parameters of Madeira wines and concluded that their pH was unaffected by these two factors and ranged between 3.26 and 3.42. Acidity is one of the most important characteristics to be controlled when making a wine. The total acidity is the result of the sum of all the organic acids present in the wine and has a direct and positive influence on the conservation of the wine, because it inhibits the development of microorganisms. Volatile acidity is another important parameter in wines, because above a threshold it shows deterioration of the wine due to production of acetic acid during yeast fermentation or also during aging in oak barrels by the chemical hydrolysis of hemicellulose [26]. The experimental ranges for these two parameters were: (i) 7.28 (_solera_ 1996) and 10.01 g tartaric acid L\({}^{-1}\) (_solera_ 1960), and (ii) 1.01 (_solera_ 1975) to 1.50 g acetic acid L\({}^{-1}\) (_solera_ 1980), respectively (Table 1). Consequently, all experimental values of the total and volatile acidities were above and below the legal thresholds for _Fondillon_ wines, respectively, and can be declared as appropriate; the sample _solera_ 1980 was just in the legal threshold for the volatile acidity. [PERSON] et al. [25] also reported that total and volatile acidity seem to increase with aging for all types of Madeira wines, for samples up to 10 years old, and then, the contents were stable and below the maximum concentration admissible, for example 1.2 g L\({}^{-1}\) for the volatile acidity.