# In-Depth Aroma and Sensory Profiling of Unfamiliar Table-Grape Cultivars
## 3 Discussion  
Relationships among Key Aroma Compounds, Odor-Active Compounds, Aromatic Series, and Consumer-Liking Scores  
Twenty-six of the 100 compounds emerged as the key compounds relating to predicted aroma consumer likings (Table S9). Of the 26, only 13 compounds (OAVs > 1; Tables S3 and S4) contributed to both consumer liking and aroma intensity. Also, as in popular cultivars [(10)], octanal (VIP = 1.60) and \(\beta\)-ionone (VIP = 1.98) determined the overall aroma quality of unfamiliar cultivars. The other 13 volatiles, despite remaining non-aromatic (OAVs < 1), influenced consumer liking by interacting with other aroma compounds [(6; 10)]. On the other hand, it was interesting to note that the esters responsible for rich fruity notes failed to influence consumer liking. Generally, volatiles affect the overall aroma in two ways: directly, by being active, and indirectly, via blending and the resulting interactions (e.g., additive, etc.) [(10; 34; 35)]. It is possible that esters followed neither of these two phenomena, and hence, were ineffective in influencing consumer liking. This imposes a major challenge in determining the relative contributions made by a large number of diverse chemicals to flavor and liking [(35)]. Between the two table-grape groups (unfamiliar and popular), the cultivars A, b, and i (see Figure 5 for cultivars corresponding to lower-case letters) showed the lowest scores, whereas G, P, and e cultivars showed the highest scores (Table S8). The scores of the remaining cultivars ranged from 3.5 to 4.5. Based on these scores, the aromatics were classified into four groups (Figure 6a): excellent (scores > 4.5), good (4.0-4.5), average (3.5-4.0), and poor aroma (<3.5). Analysis of key volatiles in these groups (Figure 6a) revealed that the contents were overall low, resulting in low scores, especially for b, i, and A. However, as their contents increased only to a certain extent, the liking scores increased as shown by the average aroma cultivars (3.5-4.0). Any further increase, as that which occurred in good-aroma cultivars, did not increase the liking scores. On the other hand, an increase in key volatiles of cultivars such as s, f, a, and e showed both positive and negative relationships with the liking scores. These patterns emphasized that consumer liking depended on the combination of positive and negative relationships, offering additional perspective to the phenomenon of aroma perception. These combinations, termed in this study as aroma combinations (AC; Figure 6b), are as follows, based on the contents of key compounds: (I) < (II) < (IV) < (V) < (III). This grouping revealed that a high content of certain volatiles in some cultivars lowered their liking score. This is why the grapeberries with only an appropriate AC, and not the highest aroma (Figure 6b), demonstrated high liking scores, which eventually led to consumer preference. Akin to popular cultivars [10], the unfamiliar cultivars also followed the five primary aromatic series (Figure S1a,b), further corroborating that all table grapes possess such aromas. Just like the primary series, the seven secondary series, including apple, citrus, orange, rose, geranium, violet, and honey, endowed the cultivars with specific aroma characteristics. For instance, although the cultivars G and P both showed high scores, they belonged to different groups, and differed in aroma OAV profiles (Figure 2i). Similarly, of the popular cultivars, consumers preferred Shine Muscat (e) with a balsamic aroma (primary series) [10]. Interestingly, even though the balsamic aroma was much lower in all unfamiliar cultivars, some of them such as P and G obtained high liking scores. This could be attributable to their unique inherent aroma influencing the consumer likings. Furthermore, the cultivar P had rich citrus, grape, rose, lavelander, and marshallow aromas, whereas G showed high values for orange, lemon, and floral aromas (Figure 2i).