## 3 Results and Discussion
### GC-MS Assay of Specimens before and after Fermentation
#### 3.4.2 Volatile Flavor Compounds of Four Groups of Unfermented Specimens
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Serial Number**} & \multirow{2}{*}{**Retention Time/Min**} & \multirow{2}{*}{**Odor Substances**} & \multicolumn{3}{c}{**Relative Content (\%)**} \\  & & & **CP-0 h** & **CPB-0 h** & **CPY-0 h** & **CPBY-0 h** \\ \hline  & & **Hydrocarbon** & **0** & **9.81** & **16.49** & **25.49\%** \\
1 & 3.26 & 2-propylene-cyclobutene & ND & ND & 3.09\% & ND \\
2 & 15.37 & 1-nonene & ND & 9.81\% & ND & ND \\
3 & 24.95 & 2-tridecylene & ND & ND & ND & 2.00\% \\
4 & 21.45 & 1,1,2,3,4,4-hexachloro-1,3-butadiene & ND & ND & 3.61\% & ND \\
5 & 29.35 & (Z)-7-hexadecene & ND & ND & 2.16\% & ND \\
6 & 15.84 & undecane & ND & ND & ND & 3.20\% \\
7 & 20.69 & dodecane & ND & ND & 4.80\% & 9.24\% \\
8 & 23.67 & 2-methyl-dodecane & ND & ND & ND & 1.48\% \\
9 & 27.06 & 6-cyclohexyl-dodecane & ND & ND & ND & 1.21\% \\
10 & 25.36 & tridecane & ND & ND & 2.83\% & ND \\
11 & 28.39 & 3-methyl-ridecane & ND & ND & ND & 5.63\% \\
12 & 24.12 & 2,4,6-trimethyl-decane & ND & ND & ND & 2.73\% \\  & & **Aleoh** & **25.32\%** & **18.46\%** & **19.98\%** & **19.03\%** \\
1 & 7.29 & 1-hexanol & 16.21\% & 14.52\% & 11.27\% & 11.56\% \\
2 & 10.36 & 1-Octen-3-ol & 4.46\% & 3.94\% & 5.67\% & 3.32\% \\
3 & 13.01 & 4-ethyl-1-octyn-3-ol & ND & ND & 3.04\% & ND \\
4 & 14.71 & 3-deoxy-2-ol & 4.65\% & ND & ND & ND \\
5 & 12.06 & \multicolumn{2}{c}{trans-2-undecen-1-ol} & ND & ND & 1.69\% \\
6 & 19.28 & 1-methyl-4-(1-methylethyl)- & ND & ND & 2.46\% \\  & & cyclohexanol & **44.29\%** & **50.95\%** & **43.08\%** & **39.91\%** \\
1 & 5.29 & hexanal & 20.91\% & 8.32\% & 15.27\% & 6.58\% \\
2 & 8.12 & heptanal & 7.23\% & 0.24\% & ND & ND \\
3 & 12.72 & (E)-2-octenal & 7.21\% & 8.86\% & 7.45\% & 8.46\% \\
4 & 13.90 & nonanal & 9.79\% & 13.69\% & 11.12\% & 13.0\% \\
5 & 16.03 & decanal & 5.68\% & 9.64\% & 6.65\% & 9.72\% \\
6 & 17.58 & undecanal & 2.55\% & 2.45\% & ND & ND \\
7 & 10.12 & benzaldehyde & 3.36\% & 3.06\% & 2.59\% & 2.09\% \\
8 & 23.08 & pentadecane aldehyde & 7.56\% & 4.69\% & ND & ND \\  & & **Ketone** & **0** & **0** & **4.38\%** \\
1 & 31.59 & 2-hydroxy-4-methoxyacetophenone & ND & ND & ND & 2.86\% \\
2 & 25.82 & 3-hydroxy-2-butanone & ND & ND & ND & 1.52\% \\  & & **Acids** & **0** & **0** & **3.32** & **0** \\
1 & 30.46 & 2-ethylhexylester-pentanoic acid & ND & ND & 3.32 & ND \\  & **Esters** & **0** & **7.43\%** & 5.30\% & **0** \\
1 & 7.56 & hexyl formate & ND & 7.43\% & ND & ND \\
2 & 11.91 & 3-methyl-oxinane-2-carboxylic & ND & ND & 5.30\% & ND \\  & & acid-methyl ester & **0** & **4.22\%** & **3.62\%** & **4.87\%** \\
1 & 12.16 & maltol & ND & 3.86\% & 3.16\% & 3.95\% \\
2 & 14.73 & 2-methoxy-phenol & ND & 0.36\% & 0.46\% & 0.92\% \\  & & **Others** & **10.39\%** & **9.13\%** & **8.21\%** & **6.32\%** \\
1 & 10.89 & 2-pentlyfuran & 9.78\% & 8.54\% & 7.15\% & 5.76\% \\
2 & 4.05 & dimethyl sulfide & 0.61\% & 0.59\% & 1.06\% & 0.56\% \\ \hline \hline \end{tabular} Note: ND means not detected.  
\end{table} 
Table 2: Volatile odor substances in four groups of unfermented specimens. Previous investigations revealed that there were more than 10 crucial odor-active flavors affecting the aroma of legume milk, including 1-octene-3-alcohol, hexanal, isoamyl alcohol, (E)-2-octenal, and nonanal [2; 19]. 1-Octene-3-alcohol and hexanal, which share grassy and agar-like characteristics, are the most crucial off-flavor substances in legume milk [2; 21]. As illustrated in Table 3, hexanal, 1-octene-3-ol, and other flavor components were detected in all four unfermented specimens, which are responsible for the undesirable flavor in chickpea milk. Interestingly, compared with CP specimen (20.91%), the relative amounts of hexanal in CPY, CPB, and CPBY specimens decreased to 15.27%, 8.32%, and 6.58%, respectively. This substance is formed by the conversion of LOX, which catalyzes fatty acids, proteins, and other precursors of legumes and yarn [36; 38]. The threshold of hexanal was low and had a strong effect on the presentation of flavor.