## 2 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Kinds**} & \multirow{2}{*}{**Aroma Volatiles**} & \multicolumn{4}{c}{**Danghansuli**} & \multicolumn{4}{c}{**Nanguoli**} \\ \cline{3-8}  & & **CK** & **Linoleic Acid** & **Linolenic Acid** & **CK** & **Linoleic Acid** & **Linolenic Acid** \\ \hline \multirow{8}{*}{Esters} & Ethyl octanoate & \(3.1\pm 0.6\) & \(0.6\pm 0.0\) & - & \(2.2\pm 1.1\) & \(0.9\pm 0.2\) & \(1.8\pm 0.2\) \\  & Methyl nonanoate & - & \(0.3\pm 0.1\) & \(0.4\pm 0.0\) & - & - \\  & Ethyl (\(E\))-2-octenoate & - & - & - & \(1.7\pm 0.8\) & \(1.4\pm 0.1\) & \(3.9\pm 0.1\) \\  & Methyl 4-decenoate & - & \(2.2\pm 0.3\) & \(1.8\pm 0.8\) & - & \(1.0\pm 0.2\) & - \\  & Methyl decanoate & - & \(1.0\pm 0.0\) & \(1.3\pm 0.4\) & - & - & - \\  & Hexyl hexanoate & - & \(0.5\pm 0.1\) & \(0.4\pm 0.1\) & - & - & - \\  & Methyl (\(E\),\(Z\))-2,4-decenidenote & - & \(5.4\pm 0.9\) & \(3.6\pm 1.0\) & \(2.8\pm 1.5\) & \(3.4\pm 0.2\) & \(8.5\pm 1.3\) \\  & Ethyl (\(E\),\(Z\))-2,4-decidenoate & - & \(0.9\pm 0.2\) & \(1.2\pm 0.4\) & \(9.6\pm 4.1\) & \(5.5\pm 1.2\) & \(19.0\pm 1.2\) \\  & Methyl dodecanoate & - & \(0.6\pm 0.1\) & \(0.8\pm 0.1\) & - & - & \(1.2\pm 0.3\) \\  & Methyl tertadecanoate & - & - & \(0.1\pm 0.0\) & - & - & \(0.5\pm 0.1\) \\  & Methyl hexadecanoate & - & \(1.8\pm 0.7\) & \(1.7\pm 0.2\) & - & - & - \\  & Subtotal & \(197.9\)\({}^{\rm(C,d)}\) & \(409.4\)\({}^{\rm\AA}\) & \(285.1\)\({}^{\rm\,[\rm\AA}\) & \(664.1\)\({}^{\rm\,[\rm\AA}\) & \(1104.4\)\({}^{\rm\,[\rm\AA}\) & \(1163.4\)\({}^{\rm\,[\rm\AA}\) \\ \hline \multirow{8}{*}{Aldehydes} & Hexanal & \(16.7\pm 2.1\) & \(9.2\pm 1.6\) & \(3.7\pm 4.0\) & \(131.7\pm 23.1\) & \(44.1\pm 3.1\) & \(4.3\pm 0.6\) \\  & 2-Hexanal & \(8.1\pm 2.6\) & \(2.6\pm 0.1\) & \(9.0\pm 7.0\) & - & - & - \\  & Nonanal & \(2.2\pm 0.4\) & \(0.5\pm 0.1\) & \(1.6\pm 0.4\) & - & - & - \\  & Decanal & \(0.9\pm 0.1\) & - & - & - & - & - \\  & Subtotal & \(27.9\)\({}^{\rm\,[\rm\AA}\) & \(12.3\)\({}^{\rm\,[\rm\AA}\) & \(131.7\)\({}^{\rm\,[\rm\AA}\) & \(44.1\)\({}^{\rm\,[\rm\AA}\) & \(4.3\)\({}^{\rm\,[\rm\AA}\) \\ \hline \multirow{8}{*}{Alcohols} & Ethanol & \(5.5\pm 1.7\) & \(3.1\pm 0.9\) & \(5.0\pm 2.0\) & \(7.8\pm 2.3\) & \(14.4\pm 0.1\) & \(18.1\pm 5.5\) \\  & (\(E\))-2-Hexen-1-ol & \(0.2\pm 0.1\) & \(2.4\pm 0.2\) & \(10.2\pm 1.7\) & - & \(2.6\pm 0.2\) & \(1.7\pm 0.2\) \\  & 1-Hexanol & \(1.9\pm 1.3\) & \(86.9\pm 1.4\) & \(23.6\pm 3.3\) & \(33.3\pm 3.3\) & \(139.5\pm 1.2\) & \(4.9\pm 3.2\) \\  & 1-Heptanol & - & \(3.2\pm 1.6\) & - & - & - & - \\  & Octen-2-ol & - & \(4.4\pm 0.7\) & - & - & - & - \\  & 1-Octanol & \(0.3\pm 0.0\) & \(1.9\pm 0.5\) & \(0.5\pm 0.1\) & \(0.7\pm 0.2\) & \(0.8\pm 0.1\) & \(1.2\pm 0.1\) \\  & (\(E\))-2-Octen-1-ol & - & \(1.7\pm 0.0\) & - & - & - & - \\  & Subtotal & \(7.9\)\({}^{\rm\,[\rm\AA}\) & \(103.6\)\({}^{\rm\,[\rm\AA}\) & \(39.3\)\({}^{\rm\,[\rm\AA}\) & \(41.9\)\({}^{\rm\,[\rm\AA}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._The different characters of the key enzymes and the different content of linoleic acid and linoleic acid maybe explain the varying volatile ester-forming capacities in different pear cultivars. The enhancement of precursor contents may be a more feasible method of increasing volatile esters in pear fruits for a cultivar. The content of alcohols also changed significantly. The main alcohols increased in \"Dangshansuli\" fruits were (_E_)-2-hexen-1-ol, 1-hexanol, 1-heptanol, 1-octanol and octen-2-ol, while 1-hexanol and 1-octanol increased in \"Nanguoli\" fruits. The total quantity of alcohol was increased for pear fruits fed on linoleic acid, while the increase was greater for \"Dangshansuli\" than \"Nanguoli\" fruits. The total quantity of alcohol was increased in \"Dangshansuli\" fruits fed on linolenic acid, but decreased in \"Nanguoli\" fruits given this compound. The contents of aldehydes were decreased in pear fruits fed on linoleic acid and linolenic acid.