## 2 Results and Discussion
### General Grape and Wine Parameters
All the varieties were harvested with Brix values of below 20, the MS30 must having the lowest value (17.3) and MT103, MV11, and Verdejo musts the highest values but never reaching 20 Brix. It is known that ethanol production increases with the sugar content of berries (the higher the content, the greater the production of ethanol), so that the volatility of odor-active compounds in wine decreases, and fruity aromas change to alcohol-associated aromas [15]. This suggests that harvesting grapes with a lower Brix could help growers to obtain grapes with organoleptic characteristics that are more suitable for the elaboration of quality white wines. The total acidity had high values in all the analyzed varieties, and in 2019 it was not necessary to adjust the acidity of the musts because the concentrations were significantly higher in most varieties, values ranging from 4.54 for MS33 to 7.38 for MC69, obtaining values significantly higher than that obtained for the Verdejo variety, in which tartaric acid reached a value of 5.26 g/L. In addition, as can be seen in Table 2, malic acid concentrations were greater than 2 g/L in nine of the white crosses analyzed and in Verdejo. As this compound is considered as a measure of quality, so it can be observed how the concentration of the malic acid was overcome with high differences for MC69 cross in both years (Tables 1 and 2), possibly imparting an added value in terms of the final wine quality. The concentrations in tartaric and malic acids (the accumulation of which may have evolved to combat the effects of aging) are related with acidity and are therefore critical for wine quality [19]. In our case, the results for the musts differed as a function of the year analyzed and, as was to be expected, total acidity was lower in wines elaborated in 2018 than in 2019. Another aspect to bear in mind is the moment of harvest and its correlation with climate change and its consequences; for example, the acidic decrease in grapes during maturation period: So many studies have been carried out on different grape varieties and have demonstrated that one of the main consequences of abiotic stress in grapes resulting from this change is an acidity decrease in grapes during the maturation period [20], so it is important to highlight the good adaptation of these crosses to the new climatic scenario. Despite the high temperatures reached during both years (close to 40 \({}^{\circ}\)C) and the low rainfall (around 100-140 mm between April and September), good levels of acidity were obtained, especially in 2019 (data not shown). Pre-veraison malic acid biosynthesis is fastest at 20-25 \({}^{\circ}\)C,whereas post-veraison malate degradation continues to accelerate up to a maximum of 50 \({}^{\circ}\)C [12], and so it is very important to control this parameter in order to reach the optimal concentration of malic acid. In our study, in order to be selected as a potential new white variety well adapted to the new scenario resulting from climate change, malic acid had to be higher than 2 g L\({}^{-1}\) or at least be close to 2 g/L\({}^{-1}\). This might be why the malic acid concentration was lower in 2018, the main difference between the two vintages being the moment of harvest. As mentioned above, malic acid degrades during the ripening process and so the more mature the grapes are, the lower the levels of malic acid. Furthermore, in some cases the lower concentrations of malic acid are also due to its lower concentrations in berries, especially in grapes grown in warmer regions. Whatever the case, any factor that affects vine growth and/or physiology directly or indirectly impacts on the fruit composition, which results in wide quality variations from one year to another [12]. As regards the analytical parameters, the wines from 2019 had, as expected, less alcohol (ranging from 10.04% for MS30 cross to 12.16% for MT103 cross). It is important to note that all the wines had a lower alcohol content in 2019, so the main objective was to obtain wines with a lower alcoholic content.