# Analysis of the Aroma Chemical Composition of Commonly Planted Kiwifruit Cultivars in China
## 3 Results and Discussion
### HS-SPME-GC-MS Analysis
#### 3.1.3 Qualitative and Quantitative Analysis of Volatile Components in Kiwifruit Samples  
To obtain a more detailed understanding of the volatile components in kiwifruit samples, the nine categories of volatile components were divided into five groups and a heat map was drawn (Figure S1A-E). See the Table S3 for detailed data. Figure S1A shows the heat map analysis of esters in kiwifruit samples. Thirty-seven ester compounds were identified, which contributed to 3.30-93.32% of the total volatile content (TVC), with an average value of 48.31%. In the study of _A. chinensis_([PERSON] et al., 2018), a total of 22 esters were detected. Of these, 12 were the same esters as in this study, which may be due to the differences in kiwifruit cultivars and sources. The highest ester content was present in Jingong No. 1 (9575.90 \(\upmu\)g/L, 93.32% of TVC), followed by Xuxiang (5264.08 \(\upmu\)g/L, 70.48% of TVC), Jinyan (2546.24 \(\upmu\)g/L, 48.83% of TVC), Huayou (1756.73 \(\upmu\)g/L, 42.66% of TVC), and Qinmei (1463.60 \(\upmu\)g/L, 42.45% of TVC). Ethyl acetate, n-propyl acetate, ethyl butanoate, hexyl formate, ethyl hexanoate, and disobutyl phthalate were the main ester volatiles in kiwifruit. Among them, ethyl acetate and ethyl butanoate were present in all kiwifruit cultivars. Ethyl butanoate had the highest ester content at 7042.01 \(\upmu\)g/L (Jinhong No. 1). In the research of [PERSON] et al. (2018) on _A. chinensis_, the same conclusion was obtained. Ethyl butanoate was the most abundant substance in ester. Ethyl butanoate, \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**NO.** & **Compounds** & **RI a** & **CAS b** & **Concentration Range** & **Cultivars c** \\  & & & & **(\(\upmu\)g/L)** & **Cultivars c** \\ \hline
154 & _p_-propyl toluene & 1106 & 1074-55-1 & 0.00–2.11 & 9 \\
155 & 6-methyltetralin & 1280 & 1680-51-9 & 0.00–1.42 & 1 \\
156 & (-)-g-Cadinene & 1435 & 3902-41-9 & 0.00–6.51 & 1 \\
157 & 6-Cadinene & 1440 & 523-47-7 & 0.00–1.95 & 1 \\
158 & 3,5-bis(1,1-dimethylethyl)-phenol & 1555 & 1138-52-9 & 0.00–19.68 & 22 A,H \\
159 & Calamene & 1537 & 483-77-2 & 0.00–10.05 & 1 \\
160 & 1-Isopropyl-4,7-dimethyl-1,2,3,5,6,8a- & - & 16729-01-4 & 0.00–4.17 & 1 \\  & hexahydronapthhalene & & & & \\
161 & 1,6-Dimethyl-4-(1-methylethyl) & 1902 & 16728-99-7 & 0.00–12.63 & 3 \\  & -(1,2,3,4,4a,7) hexahydronapthhalene & & & & \\
162 & 2,6-di-tert-Butyl-4-sec-butylphenol & 1902 & 17540-75-9 & 0.00–59.02 & 1 \\
163 & & Calalene & 1706 & 483-78-3 & 0.00–6.07 & 2 \\ \hline \multicolumn{2}{l}{_Others_} & & & & \\
164 & Ammonium carbamate & - & 1111-78-0 & 4.42–28.61 & 23 S,A,H \\
165 & Aether & 495 & 60-29-7 & 0.00–9.33 & 19 A \\
166 & Methylsulfide & 471 & 75-18-3 & 0.00–4.97 & 12 S,A \\
167 & Ammonium acetate & 630 & 631-61-8 & 0.00–3.77 & 1 \\
168 & Propionic anhydride & 921 & 123-62-6 & 0.00–24.21 & 17 A,H \\
169 & Methyltetrahydropropyl & 770 & 10141-72-7 & 0.00–2.23 & 1 \\
170 & methoxy-phenyl-oxime & 1301 & - & 53.75–291.96 & 23 S,A \\
171 & Anisole & 870 & 100-66-3 & 0.00–1.80 & 1 \\
172 & 4-Octadecylmorpholine & 2511 & 16528-77-1 & 0.00–20.09 & 1 \\ \hline \end{tabular}  
* Retention index of compounds on DB-1 MS chromatographic columns. b CAS, Chemical Abstracts Service Registry Number of the odorant. c Number of kiwifruit cultivars with volatile compounds. c Volatile components contained in Sungold. a Volatile components contained in Hort16A. H Volatile components contained in Hayward.  
\end{table} 
Table 2: _Cont._which is fruity and sweet, is found in many other fruits, such as mango [19] and melon [20]. Based on this, ethyl butanoate is one of the esters that has a greater effect on the aroma components of kiwifruit samples and is regarded as one of the core aroma components in kiwifruit. The lowest ester content was present in Hayward (64.90 \(\upmu\)g/L, 3.74% of TVC), and the lowest proportion of esters in TVC was found in Sungold (341.80 \(\upmu\)g/L, 3.30% of TVC). The ester concentration in Hort16A was 77.59 \(\upmu\)g/L, 7.20% of TVC.