## 2 Results and Discussion
### Quantitation of the Key Odorants and Calculation of Odor Activity Values (OAVs)  
Table 4 lists the calculated mean values for each volatile compound in doubanjiang. Among these odorants, 3-methylbutanoic acid had the highest concentration in doubanjiang (144.8 \(\updownarrow\)g/kg), followed by phenylethyl alcohol (129.2 \(\updownarrow\)g/kg), acetic acid (103.2 \(\updownarrow\)g/kg), ethyl isovalerate (62.3 \(\updownarrow\)g/kg), limonene (32.4 \(\updownarrow\)g/kg), linalool (33.2 \(\updownarrow\)g/kg), methional (32 \(\updownarrow\)g/kg) and 2-methoxyphenol (27.2 \(\updownarrow\)g/kg). Odor activity values (OAVs) were used to estimate the contribution of individual aroma compounds  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**No.** & **Compounds** & **Characteristic Ion (m/z) a** & **Concentrations (\(\updownarrow\)g/kg)** & **Odor Threshold (\(\updownarrow\)g/L in Water) b** & **OAV c** \\ \hline
3 & ethyl 3-methylbutanoate & 88,57,85 & 62.29 \(\pm\) 2.25 & 0.01 & 6229 \\
28 & limonene & 68,93,67 & 32.36 \(\pm\) 1.81 & 200 & 0.16 \\
64 & linalool & 71,93,55 & 33.2 \(\pm\) 1.42 & 28 & 1.18 \\
65 & phenylethyl alcohol & 91,92,122 & 129.22 \(\pm\) 3.61 & 564.2 & 0.23 \\
89 & \(\beta\)-damascenone & 69,121 & 6.69 \(\pm\) 0.32 & 0.002 & 3345 \\
103 & acetic acid & 43,45,60 & 103.2 \(\pm\) 2.75 & 22 & 4.69 \\
106 & 3-methylbutanoic acid & 60,43,87 & 144.75 \(\pm\) 4.65 & 70 & 2.07 \\
124 & 3-isobutyl-2-methoxyprazine & 124,151 & 4.98 \(\pm\) 0.32 & 0.002 & 2490 \\
126 & 2-methoxyphenol & 109,124,81 & 27.24 \(\pm\) 1.25 & 3 & 9.08 \\
134 & 3-methylbutanal & 44,58 & 1.13 \(\pm\) 0.08 & 1.1 & 1.03 \\
136 & phenylacaldehyde & 91,92,120 & 6.64 \(\pm\) 0.43 & 4 & 1.66 \\
152 & sotolome & 83,128 & 16.02 \(\pm\) 1.09 & 0.01 & 1602 \\
155 & methional & 48,76,104 & 32.0 \(\pm\) 1.07 & 0.2 & 160 \\ \hline \hline \end{tabular}  
* The first qualify ion was selected as a quantifying ion in quantitative analysis, which is based on 8-point external standard curves in the SAFE. b Odor threshold was taken from Volatile Compounds in Food (VCF) database [[http://www.vcf-online.nl/OFTVC](http://www.vcf-online.nl/OFTVC)]([http://www.vcf-online.nl/OFTVC](http://www.vcf-online.nl/OFTVC)) CompoundSearch.cfm. Odor thresholds were determined in water. c OAV value = average concentrations (\(\updownarrow\)g/kg).
* Odor threshold (\(\updownarrow\)g/L in water).  
\end{table}
Table 4: Characteristic ion, concentrations, threshold, and odor activity values (OAVs) of the key aroma compounds in doubanjiang after solvent assisted flavor evaporation (SAFE).  
to the overall flavor of doubanjiang. As shown in Table 4, the concentrations of the selected key aroma volatiles exceeded their estimated odor threshold, suggesting that they may be responsible for the doubanjiang aroma. Ethyl 3-methylbutanoate showed the highest OAV, exceeding its threshold (0.01 ug/L in water) by a factor of 6229, followed by \(\beta\)-damascenone, 3-isobutyl-2-methoxypyrazine and sotolone, with OAVs of 3345, 2490 and 1602, respectively. These results correlated well with the conclusion that ethyl 3-methylbutanoate had a high OAV in doubanjiang [3]. \(\beta\)-Damascenone was the key odorant in red wine and Chinese liquor, with a high OAV, and significantly imparted the overall aroma of Chinese liquor [16]; sotolone showed the highest OAVs in soy sauce [19].