## 2 Results and Discussion
### Analysis of Aroma-Active Volatiles in Cooked Sorghum by Using GC-O/MS
#### 2.3.1 Sweet/Fruity  
Sweet/fruity was found to be the major aroma character in both types of cooked sorghums, with the glutinous sorghum containing 12% more sweet/fruity aroma than the non-glutinous sorghum. Four types of compounds (terpenes, heterocyclics, alcohols, and ketones) provided the sweet/fruity aroma note in the cooked sorghums. Among the four terpenes (elemene, \(\beta\)-damascenone, geranyl acetone, and vanillin), \(\beta\)-damascenone and geranyl acetone were significant contributors to the overall aroma of the cooked \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Aroma Impression 1  & **Significance 2  & **Significance 3  \\ \hline \multirow{2}{*}{sweet/fruity} & 2-octanone, 2,3-octanedione, 2-nonanone, octanol, \(\beta\)-elemene, \(\beta\)-damascenone, phenethyl alcohol, geranyl acetone, \(\gamma\)-octalactone, \(\gamma\)-noncalactone, vanillin & 32.17 \(\pm\) 2.32 & 28.42 \(\pm\) 1.48 & ** \\ \hline \multirow{2}{*}{green} & 2-methylbutanal, 3-methylbutanal, hexanal, 2-pentylfuran, & & & \\  & nonanal, (E)-2-octanal, 1-heptanol, (-)-\(\alpha\)-ccdrene, thuiopesene, (E)-2-decant, (_E_)-2-4-nonanal & 33.33 \(\pm\) 1.75 & 26.58 \(\pm\) 1.51 & *** \\ \hline \multirow{2}{*}{ floral} & hexanol, \(\beta\)-terpineol, phenylacetaldehyde, acetophenone, (E)-\(\beta\)-ionone, (_E_)-nerolidol & 13.67 \(\pm\) 1.67 & 13.08 \(\pm\) 1.51 & ns \\ \hline \multirow{2}{*}{fatty} & octanal, (_E_)-2-heptcal, decanal, (E)-2-undecanal, (_E_, _E_)-2-4-decadional, octanoic acid, decanoic acid & 14.83 \(\pm\) 0.75 & 13.75 \(\pm\) 1.80 & ns \\ \hline \multirow{2}{*}{volatile acids} & acetic acid, butanoic acid, 3-methyl-butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid & 14.17 \(\pm\) 0.75 & 16.42 \(\pm\) 1.06 & ** \\ \hline \multirow{2}{*}{citrus-like} & \(\alpha\)-terpinene, (E)-\(\beta\)-terpineolene, \(\alpha\)-limonene, \(\gamma\)-terpinene, & & & \\  & 2-undecanone & & & \\ \hline \multirow{2}{*}{roasty/nutty} & furfural, benzaldehyde, 2-acetylpyrrole & 6.92 \(\pm\) 0.61 & 7.17 \(\pm\) 0.69 & ns \\ \hline \multirow{2}{*}{miscellaneous (sulphurly/smokroy/mushroom)} & dimethyl disulfide, 1-octen-3-ol, 2-methoxy-4-vinylphenol & 7.58 \(\pm\) 0.79 & 7.17 \(\pm\) 0.47 & ns \\ \hline \hline \end{tabular}  
* The aroma characteristics; 2 The summed aroma intensities of odorant compounds were represented as the mean value of sextupplicate samples \(\pm\) standard deviation; 3 Symbols indicate a significant aroma intensity difference between two sorghum samples. Significance: \({}^{***}\), \(p<0.001\) (very highly significant); \({}^{***}\), \(p<0.01\) (highly significant) \({}^{***}\), \(p<0.05\) (significant); \({}^{*}\)ns, \(p>0.05\) (not significant).  
\end{table} 
Table 4: Summed aroma intensities of each aroma group present in the cooked glutinous and non-glutinous sorghum samples. Figure 4: (**A**) Gas chromatography-mass spectrometry (GC-MS) and (**B**) gas chromatography-olfactory (GC-O) chromatograms of cooked glutinous sorghum. Numbers correspond to the compounds listed in Table 3.  
sorghums. During the GC-O/MS analysis, although no obvious peak for \(\beta\)-damascenone was observed, an aroma of rich honey sweetness was sniffed at 26.84 min, with an RI of 1833 (Figure 4), and the compound was identified using its retention time and mass ions. \(\beta\)-Damascenone is an ionone isomer belonging to the isoprenoid class of compounds. These compounds often exude the aroma of lemon at low concentrations, while at high concentrations the aromas of apple, rose, and honey are expressed [16]. According to the literature, \(\beta\)-damascenone is an important aroma contributor to Chinese Baijiu [6], having extremely low aroma threshold values in air (0.002-0.004 ng/L) and water (0.00075-0.002 ug/L) [17]. \(\beta\)-Damascenone and geranyl acetone are both bound aroma compounds of sorghum, with geranyl acetone also being an important aroma compound in the soy sauce aroma type Baijiu [6]. Vanillin is another common aroma compound in Chinese Baijiu [18].