# In-Depth Aroma and Sensory Profiling of Unfamiliar Table-Grape Cultivars
## Results
### The Volatile Compounds of Unfamiliar Cultivars  
Ninety-nine volatiles (72 in both pulp and skin, 11 only in pulp, and 16 only in skin) were identified in whole berries (Tables S1 and S2). The number of alcohols (11) and esters (20) in pulp were greater than that in skin (8 and 19, respectively), whereas an opposite trend occurred for the number of aldehydes (9) and terpen (27), whereby their numbers were low in pulp juice compared to those in skin (14 and 30, respectively). Five acids, three C\({}_{13}\)-norisoprenoids, and seven C\({}_{6}\) compounds were found in both skin and pulp. Moreover, two ketones were also found in unfamiliar cultivars. The number of volatiles significantly differed between skin and pulp juice (Figure 2). Esters existed  
Figure 1: The standard chemical indices of unfamiliar table-grap cultivars. (**a**) Berry weight, (**b**) titratable acidity (TA; g/L), (**c**) total soluble solids (TSS; \({}^{\circ}\)Brix), (**d**) pH, and (**e**) sugaracid ratio (TSS/TA). The photographs (**f**) in the right panel show berries of various grape cultivars. The unfamiliar cultivars include A—Yongyou 1 #, B—Ryogyoku, C—Summer Black, D—Muscat Duke Amour, E—Cannon Hall Muscat, F—Baby Finger, G—Xiangyue, H—Jintianmeigui, I—Katta Kourgan, J—Aki Queen, K—Honey Black, L—Ougyoku, M—Benifuji, N—Rosario Rosso, O—Lilit, P—Heikuixiang, Q—Princess Seedless, R—Shinano Smile, and S—Royal. Scale bars: 25 mm. primarily in pulp, whereas the other volatiles mostly occurred in the skin, especially for the terpenes. For instance, in pulp juice (Table S1; Figure 2), esters were the predominant volatiles (69-96%) with ethyl acetate occurring as the primary compound (68-96% of total esters) in seven cultivars (A, C, G, J, K, L, and M; see Figure 1 for cultivars corresponding to upper-case letters). Particularly, P showed relatively high levels of ethyl acetate, which is typical for any cultivar derived from the Kyoho grapevine [10]. On the other hand, terpen were the predominant volatiles in the skin of three cultivars (D, P, and Q), which accounted for more than 70% of the total content (Table S2). Furthermore, C\({}_{6}\) compounds were the major volatiles (more than 49%) in the pulp juice of ten cultivars (e.g., B) and in the skin of twelve cultivars (e.g., C). Other compounds were present, but their contents were lower (<200 \(\upmu\)g/kg). The compounds that were detected in popular cultivars (68) were also present in unfamiliar cultivars. However, an additional 22 and 28 volatiles from pulp and skin, respectively, not detected in popular cultivars [10] were detected in the unfamiliar cultivars. So, in total, 99 compounds were detected in unfamiliar cultivars (Tables S1 and S2). On the other hand, four volatiles (2-heptanol, ethyl isobutyrate, ethyl 3-methylbutanoate, and rose oxide II (cis)) identified in the popular cultivars' skin were present only in the pulp (three of the four volatiles) of unfamiliar cultivars. Because of their low thresholds (Tables S3 and S4), their impact on berry aroma is expected to be negligible. Among all compounds identified, C\({}_{6}\) compounds constituted the basic background volatiles in both groups (popular and unfamiliar table grapes). The esters primarily existed in pulp juice, whereas all other volatiles mostly occurred in the skin. Nevertheless, qualitative and quantitative differences occurred between these two groups. The number of volatiles found in unfamiliar cultivars was higher than that in the popular cultivars, but the amounts were always high in the popular cultivars (Table S5). This feature, coupled with other traits such as high yield, appearance, and fruit quality attributes, rendered them popular. On the other hand, from an aroma quality perspective, breeders prefer cultivars with high-aroma content, as well as intensity. However, some volatiles may not be present because of the loss of their alleles during the breeding process, which leads to emphasizing the other traits of yield and appearance [8].