# Volatile Metabolome and Aroma Differences of Six Cultivars of _Prunus mume_ Blossoms
## 2 Results and Discussion
### Correlation between the Differential Compounds and Aroma Characteristics  
Table 4 compares the differential compounds screened based on the contents of 89 detected compounds and OAVs of 65 identified compounds in different cultivars. Six compounds including benzaldehyde, methyl benzoate, benzyl acetate, eugenol, (E)-cinnamic alcohol, and 4-allyphenol are in the lists for fifteen and nine differential compounds based on contents and OAV, respectively. All of these compounds originated from the main metabolic pathways and were of higher contents and/or lower olfactory threshold, which greatly contribute to the aroma differences of the six cultivars of _P. mume_ blossom. Furthermore, trans-\(\beta\)-ionone was screened in the OAV list owing to its extremely low olfactory threshold. Apart from three compounds, for which olfactory thresholds are not available, most of the remaining six compounds in the 15 differential compound list based on contents are of relatively higher olfactory thresholds, and are out of the list of OAV.  
Figure 5: HCA analyses of nine differential aroma compounds of six varieties of _P. mume_ blossom samples. \"\" indicates that the compound may be other isomers.  
Specifically, taking both differential compounds based on contents and OAV into account, it can be observed that (E)-cinnamic alcohol is the common characteristic compound in GLH and GF, which may confer stronger hyacinth and cinnamon scent in these two cultivars; while methyleugenol may confer slightly stronger clove and cinnamon aroma in GLH and benzaldehyde may give GF a more almond and cherry fragrance. Methyl benzoate may bring a common strong phenolic, wintergreen, and almond scent, and benzyl acetate may bring floral and jasmine base scents for JM and LE, while trans-\(\beta\)-Ionone may give a strong violet and raspberry scent for JM, and 3,4-dimethoxy-toluene a stale and musty scent for LE. DFZS is unique for the same characteristic compounds on both content and OAV sides, including methyl benzoate, eugenol, and 4-allyphenol, which impart DFZS with more prominent phenolic, wintergreen, and almond scents, clove and woody scents, and phenolic and medicinal scents. YD is quite different from other _P. mumes_ for its very abundant characteristic compounds, including benzaldehyde, benzyl acetate, eugenol, and 4-allyphenol on the basis of content and OAV, which generate rich fragrance for YD together with 2-nonenal, 3,4-dimethoxy-toluene, and trans-\(\beta\)-ionone. This is consistent with the results derived above, that YD contains the most volatile metabolites in terms of both number and amount.  
_P. mume_ blossom is rich in germplasm resources and has various unique aromas, with strong ornamental and economic value [1,8]. Research on the volatile metabolome and aroma characteristics of different cultivars of _P. mume_ blossoms is helpful for the development and utilization of _P. mume_ blossom resources. However, the formation of human olfaction and aroma is complex; based on the clarification of volatile content, the formation of aroma is not simply a simple sum of all aroma components. The same structure or homologs are prone to synergistic and additive effects, and different aroma rhythms or aroma components with large structural differences are prone to masking and inhibiting effects [27]. Therefore, the aroma characteristics of _P. mume_ blossoms still need to be studied by applying more in-depth aroma formation theories and methods.