## 2 Results and Discussion
### Concentration of Total Volatile Compounds  
The total concentration of the different families of aromas during the two years studied are shown in Figure 1. It can be difference between acids (A), alcohols (B), esters (C), terpenes and norisoprenoids (D), and miscellaneous (E). As can be seen in Figure 1, the time of harvest affected the concentration of all the aromatic groups analyzed in both seasons studied. As regards wine acids, they are derived from the grape and yeasts during fermentation and only indirectly affect wine flavor, leading to the production of fatty acid esters [21]. As it can be observed, the MT103 wine showed the highest concentration of acid compounds in both years, but especially in 2019, when the concentration also exceeded that of the Verdejo wine. The MV67 wine had the lowest concentration in 2018, while that made from MV11 had the lowest concentration in 2019. Other authors also mention a significant increase in the concentration of fatty acids when the harvest date was brought forward, such as [PERSON] et al. [22] in the Marechal Foch variety, and [PERSON] et al. [10], who explained that the concentration of medium chain fatty acids in Pinot Noir decreased with berry over ripening. On the other hand, the fatty acid concentrations in wines are also dependent on anaerobic growth conditions, must composition, grape cultivar, yeast strain, fermentation temperature, and winemaking practices [14]. However, the same yeast strains, fermentation temperatures, and winemaking practices were used in both years in our study, so the differences between years (Figure 1) were probably due to the must composition being conditioned by the earlier harvest time in 2019 which led to a lower Brix and higher tartaric and malic acid contents. The second type of volatile compound depicted in Figure 1 is the group of alcohols (Figure 1B), compounds that make a positive contribution to the aroma of wines, enhancing their aromatic complexity [19] when not present in very high concentrations. They are formed mostly from sugars under aerobic conditions, and from amino acids under anaerobic conditions by yeasts through the chemical reduction of the corresponding aldehydes, and are important for the aroma characterization of wines [23]. All the analyzed samples had higher alcohol concentrations in 2019 than in 2018, except the MS30 wine, which had similar concentrations in both years. [PERSON] et al. [22] also observed that the herbaceous C6 alcohols in Marechal Foch wine were the most consistent and showed a more pronounced reduction as a result of late harvest. Nevertheless, the interest in an early harvest, especially in warmer areas, is  
Figure 1: Total concentration of volatile compounds within the different aromatic families: Acids (**A**), alcohols (**B**), esters (**C**), terpen and norisoprenoids (**D**), and miscellaneous (**E**). Comparison between the different crosses and Verdejo as control, in two different seasons (2018 in black and 2019 in grey) expressed as mg/L (ppm). Different letters are specific to each year and show significant differences (ANOVA, LSD test). due to the resulting improvement in balance between the different qualitative components of the berry, particularly the volatile components [10]. In the 2018 season, the MV7 wine had a higher concentration of alcohols than the other wines analyzed, while the wines produced from MV11 and Verdejo had the lowest alcohol content. It is known that the alcohol content of a wine contributes positively to the aroma enhancing its aromatic complexity [24], although concentrations higher than 400 mg L\({}^{-1}\) have a negative effect due to the appearance of pungent and unpleasant notes [25]. The highest concentration of these compounds was found in MC69 and MV7 wines in 2019, while MS30 produced wines with the lowest alcohol content. The Verdejo wine also had a notably higher concentration of alcohol in this season. The concentration of alcohol for the all varieties in 2019 was higher than in the 2018 season.