# Part II--Aroma Profile of Twenty White Grapevine Varieties: A Chemotaxonomic Marker Approach
## 3 Results & Discussion
### Volatile Composition
#### 3.3.3 Variety Classification: Aromatic Relationship PCAs  
Two principal component analyses (PCAs) were carried out, with the free and glycosidic bound aromatic profile, as we did in previous studies [36; 37], in terms of testing their capacity to differentiate among varieties, to see how they place varieties according to their aromatic similarities and to check if they maintain any relationship with their corresponding genetic-geographic groups. Percentages were used instead of concentrations, since according to different studies, such as those of [PERSON] et al., [PERSON] et al., [PERSON] et al. and [PERSON] et al. [82; 83; 84; 85], they observed quantitative variations in studied compounds due to non-genetic factors, whereas the qualitative composition remained consistent. Mean data of the studied vintages were used, since our main objective was to establish the potential relationships between varieties without considering the influence of the year factor on their distribution. Figure 2 shows the free volatile aromatic profile PCA. The first two principal components (Figure 2) accounted for 58.6% of the total variance (14% and 44.6%), showing good varietal differentiation. Thiols, esters and C\({}_{13}\)-norisoprenoids were left out of the analysis as they contributed at very low percentages to explaining the variance. The aromatic clustering coincided to some extent with the genetic-geographic grouping, with varieties included in the RPP1 [34] aromatically clustered in two main groups: one embracing 'Batoca', 'Pirixileira', 'Godello' and 'Silveirina', mainly character  
Figure 2: Principal component analysis of the free-aromatic-fraction profile (percentage) of grapes. AC: acids, KET: ketones, PAHs: polycyclic aromatic hydrocarbons, ALC: alcohols, ALDH: aldehydes, C6: C\({}_{6}\) compounds, SESQ: sesquiterpenes, PHE: phenols, TER: terpenes, LAC: lactones. AG: ‘Agudelo’, A: ‘Albilla do Avia’, BA: ‘Batoca’, ‘BL: ‘Branco Lexitimo’, BM: ‘Blanca de Monterrei’, DB: ‘Dona Blanca’, FP: ‘Fernão Pires’, GF: ‘Garrido Fino’, GO: ‘Godello’, IT: ‘Italia’, JA: ‘Jarrouselto’, LA: ‘Lado’, MBM: ‘Moscated de Bago Miudo’, PA: ‘Palomino’, PI: ‘Pirixileira’, PF: ‘Planta Fina’, RA: ‘Ratito’, SI: ‘Silveirina’, TO: ‘Torronteés’, TR: ‘Treixadura’. Varieties in purple correspond to the Reconstructed Population (RPP) RPP1; varieties in grey correspond to RPP2, and varieties in green correspond to non-classified varieties in the genetic-geographical structure stablished by [PERSON] et al. [34]. ized by their content of ketones, alcohols, phenols and lactones, and a second one, which included 'Agudelo', 'Albilla do Avia', 'Branco Lexitimo', 'Fernao Pires', 'Lado', 'Ratino' and 'Treixadura'. From those varieties included in the RPP1, considered as northwestern Iberian Peninsula varieties, 'Albilla do Avia' and 'Fernao Pires' could stand out aromatically, for having a higher terpene content and being the closest to 'Italy' and 'Moscatel de Bago Miudo', two varieties noted for being highly terpenic and therefore serving as a reference for aromaticity. Regarding RPP2 varieties, 'Jarrosuelto', 'Palomino' and 'Planta Fina' were aromatically grouped fairly close in the first quadrant, and all RPP2 varieties, together with 'Torrontes' and 'Dona Branca', except for 'Moscatel de Bago Miudo', were classified in the negative side of F1. It seems that the aromatic profile clustering coincided to some degree with the genetic-geographic one. Figure 3 shows the PCA based on the glicosidically bound volatile aromatic profile. This second PCA (Figure 3) also achieved good varietal differentiation, although in this case, varieties were closer than in the previous one (Figure 2). The first two principal components accounted for 57.8% of the total variance (19.4% and 38.4%). Thiols, lactones, and phenols were left out of the analysis as they contributed at very low percentages to explaining the variance.