## 3 Results and Discussion
### Changes in VOCs during Storage
Additionally, storage at 20 \({}^{\circ}\)C contributed to a larger production of VOCs than storage at 4 \({}^{\circ}\)C. Thus, the maximum content of VOCs (117.96 mg/kg FW) appeared in fruit after 14 days storage at 4 \({}^{\circ}\)C plus 7 days at 20 \({}^{\circ}\)C.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Compounds Name**} & \multirow{2}{*}{**Molecular Formula**} & \multicolumn{4}{c}{**Content of VOCs in Pears After Storage (mg/kg FW)**} \\ \cline{3-6}  & & **Before** & **14 Days** & **21 Days** & **14 Days + 7 Days at 20 \({}^{\circ}\)C** \\ \hline Butyl acetate & C\({}_{6}\)H\({}_{12}\)O\({}_{2}\) & 7.18 \(\pm\) 0.62 & 6.16 \(\pm\) 0.51 & 11.42 \(\pm\) 1.14 & 10.17 \(\pm\) 1.21 \\ Pentyl acetate & C\({}_{7}\)H\({}_{14}\)O\({}_{2}\) & 0.40 \(\pm\) 0.05 & 0.20 \(\pm\) 0.03 & 0.48 \(\pm\) 0.06 & 0.33 \(\pm\) 0.03 \\ Hexyl acetate & C\({}_{8}\)H\({}_{16}\)O\({}_{2}\) & 19.91 \(\pm\) 1.19 & 28.36 \(\pm\) 2.56 & 45.97 \(\pm\) 4.20 & 49.54 \(\pm\) 4.6 \\ Heptyl acetate & C\({}_{9}\)H\({}_{18}\)O\({}_{2}\) & 0.16 \(\pm\) 0.01 & 0.13 \(\pm\) 0.02 & 0.16 \(\pm\) 0.03 & 0.37 \(\pm\) 0.05 \\ Butyl hexanoate & C\({}_{10}\)H\({}_{20}\)O\({}_{2}\) & 0.26 \(\pm\) 0.03 & 0.05 \(\pm\) 0.01 & 0.06 \(\pm\) 0.01 & 0.11 \(\pm\) 0.01 \\ Hexyl butyrate & C\({}_{10}\)H\({}_{20}\)O\({}_{2}\) & 0.20 \(\pm\) 0.03 & 0.06 \(\pm\) 0.01 & 0.11 \(\pm\) 0.01 & 0.23 \(\pm\) 0.02 \\ Octyl acetate & C\({}_{10}\)H\({}_{20}\)O\({}_{2}\) & 0.40 \(\pm\) 0.03 & 0.53 \(\pm\) 0.04 & 0.48 \(\pm\) 0.04 & 2.03 \(\pm\) 0.20 \\ Hexyl hexanoate & C\({}_{12}\)H\({}_{24}\)O\({}_{2}\) & 0.30 \(\pm\) 0.04 & 0.10 \(\pm\) 0.01 & 0.11 \(\pm\) 0.01 & 0.30 \(\pm\) 0.03 \\ Methyl palmitate & C\({}_{17}\)H\({}_{34}\)O\({}_{2}\) & 1.54 \(\pm\) 0.16 & 0.14 \(\pm\) 0.01 & 0.22 \(\pm\) 0.02 & 0.09 \(\pm\) 0.01 \\
7-Hexadecenoic acid & C\({}_{17}\)H\({}_{32}\)O\({}_{2}\) & 0.18 \(\pm\) 0.02 & - & - & - \\ methyl ester & C\({}_{18}\)H\({}_{36}\)O\({}_{2}\) & 0.14 \(\pm\) 0.02 & - & - & - \\ Ethyl palmitate & C\({}_{19}\)H\({}_{36}\)O\({}_{2}\) & 2.12 \(\pm\) 0.26 & 0.34 \(\pm\) 0.03 & 0.77 \(\pm\) 0.06 & 0.17 \(\pm\) 0.03 \\ Ethyl oleate & C\({}_{20}\)H\({}_{38}\)O\({}_{2}\) & 0.14 \(\pm\) 0.01 & 0.22 \(\pm\) 0.02 & 0.40 \(\pm\) 0.05 & 0.09 \(\pm\) 0.01 \\  & & 32.93 \(\pm\) 3.58 & 36.29 \(\pm\) 3.94 & 60.18 \(\pm\) 6.21 & 63.43 \(\pm\) 6.82 \\
1-Butanol & C\({}_{4}\)H\({}_{10}\)O & 0.84 \(\pm\) 0.07 & 1.12 \(\pm\) 0.14 & 1.17 \(\pm\) 0.17 & 0.78 \(\pm\) 0.09 \\
1-Hexanol & C\({}_{6}\)H\({}_{14}\)O & 1.14 \(\pm\) 0.15 & 1.28 \(\pm\) 0.12 & 1.91 \(\pm\) 0.45 & 1.17 \(\pm\) 0.19 \\
1-Octen-3-ol & C\({}_{8}\)H\({}_{16}\)O & 0.84 \(\pm\) 0.06 & - & - & - \\
3-Cyclopentyl-1- & C\({}_{8}\)H\({}_{16}\)O & 0.30 \(\pm\) 0.04 & 0.41 \(\pm\) 0.03 & 0.40 \(\pm\) 0.05 & 1.09 \(\pm\) 0.15 \\ propanol & Linalool & C\({}_{10}\)H\({}_{18}\)O & 0.12 \(\pm\) 0.01 & - & - & - \\
1-Octanol & C\({}_{8}\)H\({}_{18}\)O & 0.43 \(\pm\) 0.03 & 0.19 \(\pm\) 0.03 & 0.13 \(\pm\) 0.01 & 0.30 \(\pm\) 0.04 \\
2-Octen-1-ol & C\({}_{8}\)H\({}_{16}\)O & 0.59 \(\pm\) 0.07 & - & - & - \\
1-Nonanol & C\({}_{9}\)H\({}_{20}\)O & 0.13 \(\pm\) 0.01 & - & - & - \\ Z-4-Dodecenol & C\({}_{12}\)H\({}_{24}\)O & 0.11 \(\pm\) 0.01 & - & - & - \\ Farnesol & C\({}_{15}\)H\({}_{26}\)O & 0.22 \(\pm\) 0.02 & 0.13 \(\pm\) 0.01 & 0.16 \(\pm\) 0.02 & 0.31 \(\pm\) 0.02 \\ Bergamod & C\({}_{15}\)H\({}_{24}\)O & 1.45 \(\pm\) 0.16 & 0.99 \(\pm\) 0.14 & 0.78 \(\pm\) 0.07 & 1.67 \(\pm\) 0.11 \\
2-Decen-1-ol & C\({}_{10}\)H\({}_{20}\)O & 0.09 \(\pm\) 0.01 & 0.79 \(\pm\) 0.08 & 0.82 \(\pm\) 0.09 & 1.05 \(\pm\) 0.16 \\
1,3-Octenoid & C\({}_{8}\)H\({}_{18}\)O\({}_{2}\) & - & 11.06 \(\pm\) 1.23 & 9.42 \(\pm\) 0.87 & 5.28 \(\pm\) 0.64 \\
3,5-Di-tert-butylphenol & C\({}_{14}\)H\({}_{22}\)O & 0.19 \(\pm\) 0.03 & 0.50 \(\pm\) 0.06 & 0.66 \(\pm\) 0.08 & 0.66 \(\pm\) 0.09 \\ Subtotal & & 6.45 \(\pm\) 0.61 & 16.47 \(\pm\) 1.73 & 15.45 \(\pm\) 1.15 & 12.31 \(\pm\) 1.31 \\
1-Hepten-3-one & C\({}_{7}\)H\({}_{12}\)O & 0.32 \(\pm\) 0.04 & 0.16 \(\pm\) 0.02 & 0.17 \(\pm\) 0.02 & 0.17 \(\pm\) 0.03 \\ Sulactone & C\({}_{8}\)H\({}_{14}\)O & 0.36 \(\pm\) 0.05 & 0.31 \(\pm\) 0.03 & 0.42 \(\pm\) 0.03 & 0.36 \(\pm\) 0.05 \\ Damascenone & C\({}_{13}\)H\({}_{18}\)O & 1.05 \(\pm\) 0.10 & 1.16 \(\pm\) 0.11 & 1.05 \(\pm\) 0.10 & 0.79 \(\pm\) 0.06 \\ Subtotal & & 1.73 \(\pm\) 0.12 & 1.63 \(\pm\) 0.12 & 1.64 \(According to previous studies, esters play an essential role in fruit aroma, and become more abundant after storage [28; 29].