## 3 Results and Discussion
### Volatile Composition
#### 3.3.3 Volatile Relationship between Varieties  
With the main objective of better visualizing the results obtained in the free and bound volatile compound determination and checking if it is possible to find any relationship among varieties based on their aromatic profile, two principal components analyses (PCA) were performed. The ACPs were made with the percentages of each family, according to studies on other types of compounds, such as phenolics, in which the influence of non-genetic factors, such as environment factors, on their content was more important than on their qualitative profile [88; 89; 90]. Taking into account the previous hypothesis, the present study aims to verify the same behavior with aromatic compounds and thus reduce the influence of external factors on the varietal aromatic profile, seeking to limit the results as much as possible to those triggered by their genetic influence. Figures 1 and 2 show both ACP plots corresponding to the volatile profiles of the 12 varieties, in free and bound form, respectively. They were carried out with the average percentage of the three vintages studied (2015-2017) for each volatile family. The first PCA, Figure 1, was carried out with the percentage values of the free fraction volatile families. The first two principal components explained 52.45% of the total variance (31.32% and 21.13%, respectively). F1 was primarily characterized by the contribution of PAHs, ketones, C\({}_{13}\)-norisoprenoids and phenols. F2 was characterized by C\({}_{6}\) compounds and terpenes. White varieties, together with 'Caino Bravo', were situated in the negative part of F2, principally by their higher terpene proportion in 'Albarino', 'Loureira', 'Brancellao Blanco' and 'Verdello Blanco' and the lower C\({}_{6}\) compound proportion in 'Caino Bravo' and 'Caino Blanco'. At the same time, it should be noted that 'Caino Blanco', considered to be the result of a cross among 'Caino Bravo' and 'Albarino' [17], shows a higher aromatic similarity with 'Caino Bravo' than with 'Albarino', with a considerably lower terpene proportion than 'Albarino', showing more similar percentages of acids, alcohols, ketones, PAHs and lactones with 'Caino Bravo' (Tables S2 and S3). These results could cause a higher genetic implication of 'Caino Bravo'. This variety is equally different from the rest of the red varieties by F2 because of its lower percentage of C\({}_{6}\) compounds, with a proportion lower than 50% facing 60% in most of the red varieties. Despite 'Caino Bravo' showing one of the lowest 'Brix degrees, which apparently could be different to this result, it also showed the second lowest tartaric acid rate. Another interesting result in this PCA is the proximity between 'Brancellao' and 'Brancellao Blanco', which could support the already outlined theory by [1] that 'Brancellao Blanco' is a persistent color mutation of 'Brancellao'. Figure 1: Principal component analysis on free aromatic fraction profile (percentage) of grapes. NOR: norisoprenoids, AC: acids, EST: esters, KET: ketones, PAHs: polycyclic aromatic hydrocarbons, ALC: alcohols, ALDH: aldehydes, C6: compounds C6, THIO: thiols, SESQ: sesquiterpenenes, PHE: alcohols, ALC: ketones, CL: compounds C6, THIO: thiols, SESQ: sesquiterpenenes, PHE: phenols, TER: terpenes, LAC: lactones. AL: ‘Albarino’, BR: ‘Brancellao’, BB: ‘Brancellao Blanco’, CBL: ‘Caino Blanco’, CBL: ‘Caino Bravo’, CL1: ‘[PERSON] 1’, CL2: ‘[PERSON] 2’, CT: ‘[PERSON], CS: ‘Castanál’, LO: ‘Loureira’, SO: ‘Sousón’ and VB: ‘Verdello Blanco’. Figure 2: Principal component analysis on aromatic precursor faction profile (percentage) of grapes. NOR: norisoprenoids, AC: acids, EST: esters, KET: ketones, PAHs: polycyclic aromatic hydrocarbons, ALC: alcohols, ALDH: aldehydes, C6: compounds C6, THIO: thiols, SESQ: sesquiterpenenes, PHE: phenols, TER: terpenes, LAC: lactones.