## Results and Discussion
### Volatile components in fresh Jinchen fruit juice and peel oil
#### Gas chromatography-/olfactometry (GC-/O) analysis  
It was cosidered very necessary to determine the components responsible for the quality of the aroma of Jinchen fruit, therefore, GC-O was performed for further studying the aromatic profile of Jinchen fruit juice and peel oil. The odor descriptors for all volatile components perceived by panelists in fruit juice and peel oil extracts of Jinchen fruit are shown in Table 2. As a result of the different odor thresholds of each component, not all of the compounds quantified contribute to the aroma in the juice and peel oil. However, olfactometric analysis utilizes the highly selective detector (human nose) that can detect potent low-level aroma-active compounds which could not be quantified by GC-MS (_trans_-2-hexen-1-ol, ethyl 3-hydroxyhexanoate, and six unknown compounds). \begin{table}
\begin{tabular}{l l l l l} \hline \hline \multirow{2}{*}{**Compound name**} & \multirow{2}{*}{**RI(HP-5)**} & \multirow{2}{*}{**Odor**} & \multicolumn{2}{c}{**Intensity\(\pm\)SD**} \\ \cline{3-5}  & & & **Fruit juice** & **Peel oil** \\ \hline Hexanal & 794 & Green & \(2.3\pm 0.9\) & n.d. \\ Ethyl butanoate & 795 & Fruity, Apple & \(3.8\pm 0.5\) & n.d. \\ _trans_-2-Hexenal & 849 & Green & \(1.8\pm 0.4\) & n.d. \\ _trans_-2-Hexen-1-ol & 869 & Green & \(2.6\pm 0.5\) & n.d. \\ _a_-Pinene & 930 & Piney & \(3.3\pm 0.9\) & \(3.6\pm 0.5\) \\ Camphene & 947 & Camphor & n.d. & \(1.0\pm 0\) \\ \(\beta\)-pinene & 982 & Piney & \(3.5\pm 0.6\) & n.d. \\ NI & 984 & Grassy & \(3.3\pm 0.5\) & n.d. \\ \(\beta\)-Myrcene & 992 & Lemon, Grapefruit, Musty, Spicy & \(3.6\pm 0.8\) & \(3.3\pm 0.5\) \\ Octanal & 1011 & Fruity, Citrusy & \(3.8\pm 0.4\) & \(2.9\pm 0.9\)* \\ Limonene & 1040 & Lemon, Minty, Orange & \(2.7\pm 0.8\) & \(2.5\pm 0.8\) \\ \(\gamma\)-Terpinene & 1064 & Sweet, Citrusy & n.d. & \(1.5\pm 0.5\) \\ Terpinolene & 1088 & Green & n.d. & \(2.0\pm 0\) \\ Linalool & 1104 & Fruity & \(4.0\pm 0\) & \(3.9\pm 0.4\) \\ Nonanal & 1107 & Piney & n.d. & \(1.0\pm 0.5\) \\ Ethyl 3-hydroxy-hexanoate & 1138 & Citrusy & \(2.6\pm 1.0\) & n.d. \\ \(\beta\)-Terpineol & 1146 & Green & \(3.3\pm 0.6\) & n.d. \\ Citronellal & 1156 & Minty & n.d. & \(3.0\pm 0\) \\ NI & 1167 & Camphor, Minty & \(2.8\pm 0.5\) & n.d. \\ NI & 1176 & Green & n.d. & \(2.7\pm 1.0\) \\ Terpinen-4-ol & 1186 & Green & \(2.4\pm 1.0\) & n.d. \\ _a_-Terpineol & 1196 & Lemon, Piney, Minty & \(3.5\pm 0.5\) & \(3.3\pm 1.0\) \\ Decanal & 1206 & Fruity, Soap, Balsamic & \(3.7\pm 0.6\) & \(3.6\pm 0.5\) \\ NI & 1213 & Metal & \(2.6\pm 0.8\) & n.d. \\ _trans_-Carveol & 1222 & Caraway & \(2.6\pm 0.5\) & n.d. \\ Nerol & 1232 & Lemon & \(2.8\pm 0.4\) & n.d. \\ Neral & 1244 & Rose & \(1.3\pm 0.6\) & n.d. \\ Carvone & 1250 & Caraway & \(2.3\pm 0.5\) & n.d. \\ NI & 1253 & Fruity & n.d. & \(2.0\pm 0\) \\ Geraniol & 1258 & Floral, Lemon, Minty & \(2.6\pm 0.8\) & n.d. \\ NI & 1259 & Floral & n.d. & \(2.6\pm 0.5\) \\ Gerani & 1273 & Floral, Citrusy & \(2.0\pm 0\) & \(2.0\pm 1.0\) \\ Perillaldehyde & 1278 & Green & \(2.3\pm 0.6\) & \(2.5\pm 0.5\) \\ Thymol & 1296 & Metal & \(1.0\pm 0\) & n.d. \\ _trans_,_trans_-2,4- & 1323 & Fatty & \(3.0\pm 0\) & \(2.2\pm 0.4\)* \\ Decadienal & & & & \\ _a_-Cubebene & 1352 & Herb & \(1.3\pm 0.5\) & n.d. \\ Geranyl acetate & 1386 & Sweet & \(1.2\pm 0.4\) & n.d. \\ \(\beta\)-Cubebene & 1397 & Fruity & n.d. & \(1.0\pm 0\) \\ Valencene & 1499 & Citrusy & \(2.8\pm 0.4\) & \(1.2\pm 0.4\)* \\ Bicyclogermacrene & 1500 & Green & n.d. & \(2.0\pm 0\) \\ \(\delta\)-Amorphene & 1523 & Fruity & \(2.0\pm 0.8\) & \(2.3\pm 1.0\) \\ \hline \hline \end{tabular}  
* NI: not identified by GC-MS; n.d.: not detected;
* indicates significant difference (P\(\times\)0.05) between the fruit juice and peel oil  
\end{table} 
Table 2: Aroma active compounds of fruit juice and peel oil detected by GC-O. A total of 31 components appeared to contribute to the aromatic profile in Jinchen fruit juice.