# Characterization of the Aroma of an Instant White Tea Dried by Freeze Drying
## 2 Results and Discussion
### Interactions among Major Aroma Contributors  
Interactions such as antagonism and synergism have been illustrated among aromatic compounds [12; 32]. As a result that linalool, _trans_-\(\beta\)-damascenone and camphene had the highest FD factors (FD = 64) among all the detected volatiles possessing different notes, these three compounds were chosen to explore the interaction between different notes. In order to further explore how interactions among linalool, _trans_-\(\beta\)-damascenone and camphene affect the aroma profiles, omission tests were conducted using artificial solutions consisting of linalool, _trans_-\(\beta\)-damascenone and camphene with concentrations detected in the SDE extract. As shown in Figure 3A, the interaction model of linalool and _trans_-\(\beta\)-damascenone showed higher intensities in both floral (3.6 vs. 1.7) and sweet (3.0 vs. 1.9) notes in comparison to pure solutions containing only linalool or _trans_-\(\beta\)-damascenone (\(p<0.05\)) (Figure 3A). The interaction model of linalool and camphene had similar floral note (1.7 vs. 1.2) in comparison to the pure solution of linalool, as well as similar green note (2.8 vs. 2.2) in comparison to the pure solution of camphene (Figure 3B). The interaction model of _trans_-\(\beta\)-damascenone and camphene had a decreased sweet note in comparison to the pure solution of _trans_-\(\beta\)-damascenone (1.2 vs. 1.9, \(p<0.05\)), as well as weakened green note in comparison to the pure solution of camphene (1.1 vs. 2.8, \(p<0.05\)) (Figure 3C). In addition, the interaction model of linalool, _trans_-\(\beta\)-damascenone and camphene had higher intensity of floral note than the interaction model of linalool and camphene (\(p<0.05\)), as well as a higher intensity of sweet note than the interaction model of _trans_-\(\beta\)-damascenone and camphene (\(p<0.05\)) (Figure 3D); Furthermore, the interaction model of linalool, _trans_-\(\beta\)-damascenone and camphene had the intensity of green note similar to the interaction model of _trans_-\(\beta\)-damascenone and camphene (Figure 3D); and the interaction model of linalool, _trans_-\(\beta\)-damascenone and camphene had a weaker green note than the interaction model of linalool and camphene (\(p<0.05\)) (Figure 3D). These results demonstrated that linalool and _trans_-\(\beta\)-damascenone had positive synergism interactions to promote the floral and sweet notes; linalool and camphene had no noticeable interaction to affect the odor of either linalool (floral) or camphene (green); and _trans_-\(\beta\)-damascenone and camphene had an antagonism interaction to reduce odor intensities of both _trans_-\(\beta\)-damascenone (sweet) and camphene (green). Figure 3: Interactions of linalool and _trans_-\(\beta\)-damascenone (**A**), linalool and camphene (**B**), _trans_-\(\beta\)-damascenone and camphene (**C**) and linalool, _trans_-\(\beta\)-damascenone and camphene (**D**). In each figure, different letters (a, b, c) behind columns in the same color represent significant difference in the aroma intensity (\(p<0.05\)). Previously, on one hand, [PERSON] et al. found that sub- and peri-threshold concentrations of woody compounds modified the perception of a supra-threshold fruity odor [33]; [PERSON] et al. illustrated that the fruit note from 6-methyl-5-hepten-2-one could promote the perception of sweet in tea infusions [34]. Compounds with similar structures or odors are apt to present synergistic/additive interactions to promote their odors [32]. For instance, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal showed strong addition action in a grape wine [35]; hexanal, (_E_)-2-hexenal, (_E_,_E_)-2,4-heptalien and (_E_)-2-heptenal presented a synergistic effect in the green note of oolong tea sample [32]. To our best knowledge, it is the first time to find that the synergism interaction of linalool and _trans_-\(\beta\)-damascenone positively promote both floral and sweet notes. On the other hand, [PERSON] et al.