## 2 Results and Discussion  
### Volatile Compounds from Indonesian Rice  
A number of Indonesian rice samples, including non-aromatic (IR64, C4 Raja and C4 Dewi Sri) and aromatic (Rojolele, Pandan Wangi and Mentik Wangi) varieties, were studied by the use of GC\(\times\)GC-TOFMS. The results of this chromatographic analysis for volatiles in six Indonesian rice varieties are listed in Table 1. More than a hundred volatiles were identified and most of these have been found in rice grains previously [12; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36]; while several compounds, such as 1,3-octadiene, 1-octen-3-yl acetate, isomenthol, estragole, and trans-anethole, were identified in rice samples for the first time. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Compounds**} & \multicolumn{2}{c}{**Retention Time (s)**} & \multirow{2}{*}{**Mass 3**} & \multirow{2}{*}{**References**} & \multirow{2}{*}{**Odour Strength 4**} & \multirow{2}{*}{**Odour Description 4**} \\ \cline{3-4} \cline{6-7}  & & **1D 1** & & & & & & \\ \hline
**1** & **Pentanal C1** & **435** & **2.11** & **58** & [20; 21; 22; 23; 24; 25] & **High, 1\%** & **Bready; fruity; intrity; berry** \\
2 & Acetic acid & 455 & 4.41 & 60 & [21; 22; 26] & High, 10\% & Pungent; sour; vinegar \\
3 & 2-Methylfuran C2 & 495 & 2.59 & 53 & [22] & Medium, 1\% & Ethereal; acetone; chocolate \\
**4** & **Pyridine C3** & **505** & **2.60** & **79** & [21; 23; 25; 27] & **Very high, 0.01\%** & **Sour; putrid; fishy; amine** \\
5 & 1-Pentanol C4 & 520 & 2.47 & 42 & [12; 21; 23; 25] & High, 10\% & Pungent; fermented; bread; \\
6 & Toluene C5 & 525 & 2.14 & 91 & [21; 22; 23] & & years; fused; viney \\
7 & 2-Hexanone & 540 & 2.16 & 43 & [23; 28] & & Sweet \\
**8** & **Hexanal C6** & **550** & **2.17** & **56** & [12; 20; 27; 29; 31] & & **High, 1\%** & Fruity; fungal; meaty; buttery \\
9 & Furfural C7 & 585 & 3.38 & 95 & [23; 25; 27; 32] & & & \\
10 & 2-Methylpyridine & 590 & 2.45 & 93 & [23; 27] & & & Sweet; woody; almond; \\
11 & 1,3-Octadiene * & 600 & 1.99 & 54 & & & & & \\
12 & 1-Hexanol C8 & 645 & 2.45 & 56 & [12; 23; 29] & & & \\
13 & 1,3-Dimethylbenzene & 655 & 2.14 & 91 & [12; 23; 29] & & & \\
14 & 2-Heptanone C9 & 665 & 2.18 & 58 & [20; 21; 23; 26; 27] & & & \\
15 & 2-Butylfuran C10 & 680 & 2.09 & 81 & [21; 23; 29; 30] & & & \\
16 & Heptanal C11 & 680 & 2.17 & 70 & [20; 21; 22; 29] & & & \\
17 & Styrene & 680 & 2.30 & 104 & [21; 26; 27] & & & \\
18 & 1,2-Dimethylbenzene & 685 & 2.18 & 91 & [12; 21] & & & \\
**19** & **2-Acetyl-1-pyrroline & **C33** & **700** & **2.45** & **43** & [12; 20; 21; 23; 25; 30; 31; 34] & & \\
20 & 2-Methyl-5- & & & & & & & \\
21 & isopropylfuran & 730 & 2.18 & 122 & [22] & & & \\
22 & 1-Octan-3-cl C14 & 750 & 2.32 & 41 & [20; 22; 23; 29] & & & \\
22 & Benzaldehyde C16 & 750 & 2.98 & 105 & [20; 21; 23; 25; 27; 29; 30] & & & \\
23 & 1-Ethyl-4- & & 775 & 2.14 & 105 & [21; 23] & & & \\
24 & 1-Heptanol C17 & 775 & 2.39 & 70 & [12; 22; 27; 30] & & & \\
25 & Benzonitrile & 775 & 3.27 & 103 & [29] & & & \\
**26** & **1-Octan-3-cl C19** & **785** & **2.43** & **57** & [20; 22; 22; 25; 27; 30, 31] & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: GC\(\times\)GC-TOFMS analysis for volatiles in six Indonesian rice varieties. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Compounds**} & \multicolumn{3}{c}{**Retention Time (s)**} & \multirow{2}{*}{**Mass 3**} & \multirow{2}{*}{**References**} & \multirow{2}{*}{**Odour Strength 4**} & \multirow{2}{*}{**Odour Description 4**} \\ \cline{3-4} \cline{6-9}  & & **1D 1** & & & & & & & \\ \hline
27 & \ \begin{tabular}{c} 6-Methyl-5-hepten- \\ 2-one C18 \\ \end{tabular}  & 785 & 2.26 & 43 & [20, 21, 23, 24, 25] & Medium, 10\% & \begin{tabular}{c} Citrus; green; \\ musty; lemongrass \\ \end{tabular}  \\
28 & \ \begin{tabular}{c} Phenol C20 \\ 2-Octanone C21 \\ \end{tabular}  & 790 & 2.99 & 66 & [12, 23, 26, 29] & High, 0.01\% & \begin{tabular}{c} Phenolic \\ \end{tabular}  \\
29 & \