# Part II--Aroma Profile of Twenty White Grapevine Varieties: A Chemotaxonomic Marker Approach
## 3 Results & Discussion
### Volatile Composition
#### 3.3.2 Glycosidically Bound Volatile Fraction  
Regarding the glycosylated bound aromatic profile, which provides the contribution of each family to the global aromatic precursor potential, it can be seen in Figure 1 that terpen, alcohols and sesquiterpenes contributed in higher percentages to the bound fraction than they did to the free one in most of the varieties. Phenols and esters contributed almost exclusively to the bound aromatic form. It could also be noticed that there was almost no presence or contribution of lactones in the bound fraction, contrary to what was observed in the free one. The alcohol family is the one with the highest percentage contribution, except for 'Fernao Pires', 'Italia' and 'Moscatel de Bago Miudo', where terpen were the main volatile family, 'Branco Lexitimo', 'Jarrosuelto' and 'Ratino' in which phenols were the major family and 'Garrido Fino' in which esters were the major one. These previous families were considered to have a higher contribution to the bound aromatic potential of studied varieties. Significant differences among varieties are shown in Table 3 for the content of acids, aldehydes, terpen, norisoprenoids and the total glicosidically bound fraction content, with the mean value of the latter parameter ranging from 22,010 \(\mathrm{\SIUnitSymbolMicro g}\):L\({}^{-1}\) for 'Lado' to 133,218 \(\mathrm{\SIUnitSymbolMicro g}\):L\({}^{-1}\) for 'Moscatel de Bago Miudo'. As it was previously mentioned with the free fraction, terpen were detected every year in every studied variety, showing higher contents than in their corresponding free fraction, despite having a similar percentage contribution in both fractions. It is also worth mentioning that 'Moscatel de Bago Miudo', 'Italia', 'Fernao Pires' and 'Albilla do Avia' could be highlighted for their higher contents. The first two ones also differed statistically from the rest of varieties with mean values of 98,597 and 104,834 \(\mathrm{\SIUnitSymbolMicro g}\):L\({}^{-1}\). 'Piriaileira' and 'Planta Fina' together with 'Agudelo' are those varieties in which a lower glycosidic terpene content was detected, which also corresponded to the free fraction, with 355, 873 and 851 \(\mathrm{\SIUnitSymbolMicro g}\):L\({}^{-1}\), respectively, with dihydrorenello1 being the major compound (Supplementary Table S2). As it could also be seen in Supplementary Table S2, linalool in 'Italia' and cis geraniol in 'Moscatel de Bago Miudo' were the major terpen. In contrast to the free fraction, sesquiterpenes were detected in their bound form in 19 out of the 20 varieties studied, except for 'Albilla do Avia', with trans-Z-\(\beta\)-bisabolene epoxide and patchoulane as two of the major compounds detected. Patchoulane was detected in species, such as _Eugenia lotzschiana_ O. Berg, which is considered to have important nutritional value [71], or in the essential oil of _Pogostemon cabin_ (Blanco) Benth, being referred as an important anti-inflammatory activity compound [72]. Trans-Z-\(\beta\)-bisabolene epoxide, already identified in previous studies [36; 37], was also identified in 'Merlot' wines [73]. 'Blanca de Monterrei' and 'Garrido Fino' were those varieties that showed a higher percentage contribution to the bound aromatic profile, involving no more than 1% (Figure 1). C\({}_{13}\)-norisoprenoids showed significant differences among the different varieties studied in their bound fraction, being detected only in 9 out of 20 varieties studied: 'Albilla do Avia', 'Batoca', 'Dona Branca', 'Garrido Fino', 'Godello', 'Palomino', 'Ratino' and 'Silveirina', with dihydro-\(\beta\)-ionol, with a woody-flowery and camphoraceous odor [74] and \(\beta\)-damascenone with fruity, balsamic and tobacco descriptors [75], as major compounds (Supplementary Table S2).