## 2 Results and Discussion
### Analysis of Volatile Essential Oils
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compounds** & **RI a** & **Tankan b** & **Ponkan b** & **Murcott b** \\ \hline \multicolumn{5}{c}{**Monoterepenes**} \\ \hline \(\alpha\)-thujene & 933 & N.D c & 0.74 & 0.43 \\ \(\alpha\)-pinene & 937 & 2.13 & 2.60 & 2.39 \\ sabinene & 968 & 0.60 & 1.12 & 0.93 \\ \(\beta\)-pinene & 979 & 0.07 & 1.21 & 0.72 \\ \(\beta\)-myrcene & 980 & 5.81 & 4.86 & 5.68 \\
1-bellandrene & 1002 & 0.21 & 0.23 & 0.20 \\ p-cymene & 1004 & N.D & 1.69 & 0.84 \\ limonene & 1037 & 86.13 & 72.72 & 76.34 \\ \(\beta\)-ocimene & 1052 & 0.43 & 0.24 & 0.20 \\ \(\gamma\)-terpinene & 1063 & 0.17 & 8.77 & 6.01 \\ \(\alpha\)-terpinolene & 1085 & 0.10 & 0.50 & 0.10 \\ \hline \multicolumn{5}{c}{**Sesquietrpenes**} \\ \hline \(\alpha\)-copaene & 1353 & 0.06 & N.D & 0.12 \\ \(\gamma\)-elemene & 1380 & 0.21 & N.D & N.D \\ \(\gamma\)-cadinene & 1389 & 0.11 & N.D & N.D \\ \(\beta\)-caryophyllene & 1428 & 0.37 & 0.16 & 0.49 \\ \(\gamma\)-muvulecne & 1481 & 0.08 & N.D & 0.14 \\ germacene D & 1478 & 0.09 & 0.26 & 0.18 \\ \(\delta\)-cadinene & 1497 & 0.18 & N.D & 0.15 \\ \hline \multicolumn{5}{c}{**Aldehydes**} \\ \hline \(\alpha\)nonal & 900 & 0.06 & 1.52 & 0.79 \\ decanal & 1000 & 0.07 & 0.78 & 1.14 \\
2-decanal & 1021 & 0.07 & N.D & N.D \\ perillaldehyde & 1042 & 0.05 & 0.10 & 0.12 \\ undecanal & 1100 & N.D & 0.21 & 0.17 \\ citronellal & 1132 & N.D & 0.36 & 0.50 \\ neral & 1210 & N.D & 0.21 & 0.31 \\ \(\beta\)-sinensal & 1673 & 0.18 & 0.20 & N.D \\ \(\alpha\)-sinensal & 1689 & 0.38 & N.D & 0.18 \\ \hline \multicolumn{5}{c}{**Alcohols**} \\ \hline \(\alpha\)-terpineol & 1098 & 1.40 & 0.81 & 1.05 \\ \(\alpha\)-terpineol & 1177 & 0.44 & 0.11 & 0.22 \\ \hline \multicolumn{5}{c}{**Esters**} \\ \hline \(\beta\)-geranyl acetate & 1362 & 0.16 & N.D & N.D \\ citronellyl acetate & 1382 & 0.21 & N.D & 0.20 \\ neryl acetate & 1434 & 0.18 & N.D & 0.20 \\ \hline \multicolumn{5}{c}{**Ketone**} \\ \hline \multicolumn{5}{c}{carvone} & 1217 & N.D & 0.32 & 0.18 \\ \hline \multicolumn{5}{c}{**Total terpene compound**} \\ \hline \({}^{\text{d}}\)**Total terpene compound** & **96.75** & **95.11** & **94.92** \\ \({}^{\text{e}}\)**Total oxygenated compound** & **3.25** & **4.89** & **5.08** \\ \hline \end{tabular}
\end{table} 
Table 1: Volatile constituents (%) of citrus oleoresin. shifts, and rearrangements before the reaction is terminated by deprotonation or water capture [21; 22; 23]. Myrccene is generated by losing the geranyl cation of protons, limonene is produced by losing an \(\alpha\)-terpinyl cation, and when the double bond of the \(\alpha\)-terpinyl cation is attacked by an electron, an \(\alpha\)-pinene is produced [21]. For the oleoresin from all three citrus varieties, limonene was the most abundant terpene compound, accounting for 72.72%-86.13% of the total fraction (Table 1), whereas it has previously been found to account for 90.5%-94.6% of the total fraction of oleoresin extracted from oranges by cold pressing [24; 25; 26]. Due to the terpen themselves being extremely unstable in light and heat, they are prone to deterioration when placed in storage, causing a loss of flavor and overall quality. Detependation is thus an important aspect of citrus oil processing, with the fractionation of lower terpene compounds allowing producers to limit product deterioration [13; 26]. The oxygenated compounds are generally preferable due to their characteristic flavors [13; 16; 26], which are effectively used as indicators of higher quality. For the Ponkan, Tankan, and Murcott oleoresin samples in this study, oxygenated compounds accounted for 4.89%, 3.25%, and 5.08% of the total fractions. The Ponkan oleoresin had 10 oxygenated compounds, including nonanal, decanal, perillaldehyde, undecanal, citronellal, real, \(\beta\)-sinensal, linalool, \(\alpha\)-terpineol, and carvone. The Tankan oleoresin had 11 oxygenated compounds including nonanal, decanal, 2-decanal, perillaldehyde, \(\beta\)-sinensal, \(\alpha\)-sinensal, linalool, \(\alpha\)-terpineol, geranyl acetate, citronellyl acetate, and nervl acetate.