## 3 Discussion

Table 8: _Cont._and rose oxide II (cis), and higher contents of ethyl benzoate, methyl salicate, benzyl alcohol, ethyl 3-hydroxybutyrate, ethyl heptanoate, ethyl pentanoate, ethyl lexanoate, 2-hexenoic acid ethyl ester, ethyl acetate, phenylacetaldehyde, ethyl butyrate, ethyl 3-methylbutanoate, ethyl propionate and ethyl octanoate than Muscat aromatic varieties. The current results show that only \(\alpha\)-terpineol, neral, geranic acid and linalool presented these differences between Bronx Seedless (foxy taste) and Italia (Muscat taste) variety. [PERSON] et al. [17] reported that rose oxide is the key compound to identify and select varieties with a Muscat aroma. Bronx Seedless grapes presented a lower content of rose oxide I (_trans_) than Italia grapes. Terpene content at commercial harvest (BBCH-89) in Italia and Bronx Seedless table grapes was lower than 1.0 mg L\({}^{-1}\) (749.44 \(\pm\) 10.56 and 757.23 \(\pm\) 67.34 \(\upmu\)g L\({}^{-1}\), respectively). In this way, the grapevine varieties could be grouped into Muscat (\(\geq\)6 mg L\({}^{-1}\)), non-Muscat aromatic (1-4 mg L\({}^{-1}\)) and neutral varieties (<1 mg L\({}^{-1}\)), regarding their monoterpene levels [8]. Despite the above-mentioned, the Italia and Bronx Seedless varieties could be considered as aromatically neutral based on their terpene levels. The results exposed showed that esters, fatty acids, terpenes and C6 compounds were the most abundant families of volatile compounds in Italia and Bronx Seedless table grapes, in which hexanoic acid, ethyl 3-hydroxybutyrate, ethyl octanoate, 2-hexenoic acid and octanoic acid exhibited the most important concentrations. Regarding OAVs, the most important family of volatile compounds were C\({}_{13}\)-norisoprenoids, followed by esters and C6 compounds. [PERSON] et al. [15] reported that C6 compounds, terpenes and C\({}_{13}\) norisoprenoids were the main contributors to the aroma in different table grapes obtained from a vineyard located in Shanghai, China. [PERSON] et al. [18] reported that C6 compounds were the most abundant family of volatile compounds in new seedless table grapes (TimcoTM, MagentaTM, KrissyTM and Arra15 TM), followed by aldehydes and ketones. C6 compounds derive from linoleic and linolenic acid and have been described to contribute to the green flavor in table grape berries [12; 15]. Hexanal, hexanol and (E)-2-hexenal were the major C6 compounds found in Bronx Seedless and Italia varieties (Tables 4 and 8). The hexanal to (E)-2-hexenal ratio was correlated to sweetness, an important attribute for table grape production [19]. In this way, (E)-2-hexenal was positively correlated to sourness and crunchiness and negatively to neutral flavor and sweetness [19]. As ripening advanced from BBCH-77 to BBCH-89, this ratio decreased (1.67-1.66, respectively), whereas Italia grapes showed a higher hexanal-to-(E)-2-hexenal ratio than Bronx Seedless grapes (1.69-1.54, respectively). The concentration of most of the volatile compounds analyzed increased as ripening progressed, except (Z)-3-hexenal, (E)-2-hexenol, heptanol, phenylethyl alcohol, butyl acetate, \(\upbeta\)-pinene, \(\upbeta\)-myrcene, rose oxide II (cis) and 4-terpineol (Tables 1-7). [PERSON] et al. [19] mentioned that the concentration of some volatile compounds, such as 1-hexanal, 1-hexanol, methyl hexanoate, 1-nonanal, benzaldehyde, rose-oxide, and linalool, often increases during berry development. Contrary to this, the concentration of other volatile compounds, such as gernaiol, (E)-2-octenal, and 1-pentanal, often decreases during berry ripening, whereas the levels of other volatile compounds, such as 1-decanal, (E)-2-hexenal, 1-heptanal, ggeraniol, 2-phenylethanol, and \(\upbeta\)-ionone, have been suggested to depend on the variety [19]. [PERSON] et al. [10] reported that alcohols, carbonyls, C6 compounds and terpenids were found in high amounts before veraison, while most of the esters were detected at or after veraison. C6 compounds increased in the early period of berry ripening and then decreased [10].