# Analysis of the Aroma Chemical Composition of Commonly Planted Kiwifruit Cultivars in China
## 3 Results and Discussion
### Relationship between Aroma Chemical Compositions of Kiwifruit Flesh Color and Species  
Based on the analysis of the aroma chemical compositions of different cultivars of kiwifruit, the relationship between the aroma characteristics of kiwifruit samples and their flesh colors or varieties were further analyzed. A total of 23 cultivars of kiwifruit were used, including 6 red-fleshed kiwifruits (3 yellow- and red-fleshed (middle part) kiwifruits and 3 green- and red-fleshed (middle part) kiwifruits), 8 yellow-fleshed kiwifruits, and 9 green-fleshed kiwifruits. There were 15 _A. chinensis_ fruits and 8 _A. deliciosa_ fruits.  
Based on the kinds of volatile components, Venn diagrams was used to analyze kiwifruit samples with different flesh colors (Figure 5A) and different species (Figure 5D). Red-, yellow-, and green-fleshed kiwifruits contained 80, 116, and 130 volatile components, respectively. Among them, 66 volatile components were common. Green- and yellow-fleshed kiwifruits shared 12 volatile components, green- and red-fleshed fruits shared 7 volatile components, and red- and yellow-fleshed kiwifruits shared only 2 volatile components. Based on these species, 88 volatile components were found commonly in _A. chinensis_ and _A. deliciosa_, 45 volatile components were unique to _A. chinensis_, and 38 volatile components were unique to _A. deliciosa_.  
According to the E-nose responses, 23 kiwifruit samples in this study were analyzed by PCA based on flesh color and species. Figure 5C shows the PCA of kiwifruit with different flesh colors based on the E-nose response. Principal component analysis showed that 74.37% of the variance was explained by the first two components of the PCA. The sampling points of kiwifruit samples with different flesh colors were mostly mixed together and could not be distinguished. The most prominent cultivar was the yellow-fleshed cultivar Jinshi, which was significantly different from other cultivars of kiwifruit. However, the overall results show that there were no significant differences in the aroma characteristics of kiwifruits with different flesh colors. Figure 5F shows the PCA of kiwifruit of different species based on the E-nose response. When the samples overlapped or were close to each other, they had similar flavors. The first two principal components accounted for 74.90% of the total variance, and some sampling points overlapped. This indicates that the aroma characteristics of kiwifruits with different species were different in general, but some samples were similar. Therefore, the E-nose could not effectively distinguish and identify kiwifruit samples of different flesh colors, although it could distinguish kiwifruit samples of different species to a certain extent, and it cannot be used for identification. This may be due to the current kiwifruit cultivars undergoing multiple crosses between species during the cultivation process, resulting in smaller differences between kiwifruit cultivars. Therefore, aroma characteristics have little association with flesh color and species. However, the PCA results based on GC-MS data show that neither the flesh color nor the species can be distinguished (Figure 5B,E).  
On the whole, kiwifruit samples of different flesh colors cannot be effectively distinguished by their aroma chemical compositions with the approach presented here. Based on the types of volatile components, green-fleshed kiwifruit has the most volatile components and the most complex aroma. The types of volatile components of yellow- and green-fleshed kiwifruit are more similar. Kiwifruit samples of different species can be distinguished to some extent by E-nose.  
[PERSON] et al. [11] analyzed the GC-MS results by PCA and found that the volatile compounds of _A. chinensis_ and _A. deliciosa_ were similar, which is basically consistent with the conclusions drawn in our study. The reason may be that the two species are closely related, and _A. deliciosa_ is a variant of _A. chinensis_[22].