## 2 Results
### Volatiles in Korla Pear  
The volatiles were profiled in the peels of Korla pear harvested in 2018 from 12 orchards (Table S7). Although more than 200 volatile compounds had been reported in Korla pear (Korla, 2018; 2018; 2019; 2019; 2020), there exist varies between different Korla pear samples. A total of 100 volatile compounds were detected in this article, including nine aldehydes, 20 esters, 12 alcohols, 19 terpen and 40 other volatiles such as alkanes. Aldehydes were the most abundant compounds among the volatiles (Table 3). A wide variety of esters were detected despite of their low contents. For example, hexyl acetate was detected at 82.43-818.52 \(\mu\)g/kg. Many of them such as hexyl acetate usually contribute to the impression of 'fruity' in sensory evaluation (2019). A number of terpenes which were usually detected at high concentrations in citrus essential oil were also detected in Korla pear. The concentrations of d-limonene and \(\alpha\)-farnesene were 34.16-937.00 \(\mu\)g/kg and 0.00-277.18 \(\mu\)g/kg. In general, hexanal, (_E_)-2-hexenal, nonanal, p-limonene, (_Z_)-3-hexen-1-yl acetate and hexyl acetate were abundant. For pear fruit harvested from different orchards, the volatile profiles showed great variations. On average, the number of compounds detected in the pear fruit from all 12 orchards was 69. However, only 34 compounds were commonly detected in all samples, whereas seven were unique in pear fruit from certain orchards (Table S8). For example, tetradecanoic acid was only detected in S12 with a concentration of \(1225.67\pm 825.43\)\(\mu\)g/kg. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**RT**} & \multicolumn{4}{c}{**Concentration (\(\mu\)g/g FW)**} \\ \cline{3-6}  & & **Maximum** & **Sample** & **Minimum** & **Sample** \\ \hline \multicolumn{6}{c}{**Fatty acids**} \\ Palmitic Acid & 34.41 & 14.20 \(\pm\) 8.54 & S11 & 3.64 \(\pm\) 2.93 & S6 \\ Stearic acid & 44.07 & 15.05 \(\pm\) 9.92 & S11 & 1.93 \(\pm\) 1.71 & S6 \\
**Sugars** & & & & & \\ d-(–)-Fructofuranose & 25.77 & 18492.86 \(\pm\) 4309.41 & S8 & 11285.72 \(\pm\) 359.93 & S4 \\ Fructose & 26.07 & 20999.04 \(\pm\) 4646.51 & S8 & 12012.71 \(\pm\) 22.17 & S4 \\ Psicopyranose & 27.11 & 11453.29 \(\pm\) 2590.96 & S8 & 6820.89 \(\pm\) 394.51 & S4 \\ Glucose & 28.81 & 13910.25 \(\pm\) 3120.71 & S8 & 8145.27 \(\pm\) 138.45 & S2 \\ d-Galacose & 29.31 & 303.88 \(\pm\) 47.85 & S8 & 139.70 \(\pm\) 96.73 & S11 \\ p-Glucitol & 30.26 & 24335.64 \(\pm\) 5912.74 & S8 & 12171.03 \(\pm\) 8458.33 & S11 \\ Sucrose & 48.42 & 2968.10 \(\pm\) 246.14 & S6 & 1900.73 \(\pm\) 168.91 & S12 \\ Total Amino acid & & 108.82 \(\pm\) 5.90 & S12 & 14.65 \(\pm\) 2.93 & S6 \\ Total acid & & 1099.01 \(\pm\) 41.92 & S10 & 806.63 \(\pm\) 60.89 & S9 \\ Total sugar & & 91705.26 \(\pm\) 20996.43 & S8 & 56878.51 \(\pm\) 2251.72 & S4 \\ Sugar/Acid & & 74.03 & S9 & 42.06 & S11 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**Retention Index (RD)**} & \multicolumn{2}{c}{**Concentration Range**} & \multicolumn{2}{c}{**Average Concentration**} \\  & & **(\(\mu\)g/kg FW)** & **(\(\mu\)g/kg FW)/Percentage** \\ \hline Aldehydes & & 10222.35–75589.04 & 26133.94/85.84 \\ Hexanal & 800 & 3472.75–35617.72 & 12954.25/42.55 \\ (_E_)-2-Hexenal & 854 & 2782.32–39086.40 & 12666.51/41.60 \\ Octanal & 1003 & 0.00–318.75 & 39.06/0.13 \\ Nonanal & 1104 & 211.58–798.32 & 416.57/1.37 \\ Decanal & 1206 & 7.91–144.89 & 28.74/0.09 \\
2,6,10-trimethyl-9-Undecanal & 1416 & 7.74–46.02 & 17.15/0.06 \\ Tetradecanal & 1613 & 0.16–41.36 & 6.50/0.02 \\
1-Pentadecanal & 1715 & 0.00–23.41 & 2.82/0.01 \\ Hexadecanal & 1817 & 0.00–24.99 & 2.35/0.01 \\
**Esters** & & **361.82–3206.45** & **1314.47/4.32** \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Volatile compounds detected in Korla pear from 12 orchards. _Molecules_**2020**, _25_, 5567